Microphones and Amplifiers on Shabbat
|Rabbi Yisrael Rozen|
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The question of using microphones and amplifiers on Shabbat in general, and with regard to ritual matters in particular, has been dealt with extensively in contemporary responsa literature. Two relevant factors have been discussed: the prohibition of electricity on Shabbat, and various rabbinic prohibitions such as fixing and adjusting musical instruments. Beyond these, however, I believe there is another factor which has not been discussed explicitly, but whose presence is nevertheless felt. I refer to anaversion to adopting practices instituted by the Reform movement - “against the will of the sages.” However, in Israel this is not really a problem, for the Reform have made minmal inroads into Israeli society and even in the diaspora, the case can be made that equipment today differs from that which was used in the past, and that use of a microphone does not imply identification with Reform. I will therefore deal with this issue in terms of formal prohibitions, and hope to shed new light on it.
The Minchat Yitzchak (ibid., section 1, and 1:37, section 8) cites an expert who told Rav Shmuel Yitzchak Jaffe (son-in-law of Rav Y.D. Soloveitchik of Brisk) that “One performs absolute hav’ara with every word he speaks [into a microphone].”
Other poskim assume that sparks are created when one speaks into a microphone, which violates a rabbinic prohibition, based on the mishna (Beitza 4:7): “One may not draw out sparks from a rock [on Yom Tov].” Rav Ovadia MiBartenura explains, “This is [prohibited] due to molid (creation of something new), and resembles a melacha, since he is creating this fire on Yom Tov.” Why does this merely “resemble a melacha” and not actually constitute a melacha? The Pri Megadim (OC 502:Mishbetzot Zahav) elaborates: “There is not a real melacha of lighting a flame here, for since he merely strikes the rock with a piece of metal which causes a spark,” this is not a flame, since the spark is not attached to anything (unlike the candle flame which is attached to a wick).
I wish to make it clear that none of these categories apply to contemporary microphones and amplifiers. In the age of the radio tube (a component of all amplifiers a generation ago), these categories were relevant. Radio tubes contained a filament which glowed red when heated, and the filament in turn contained electrodes (cathodes and anodes) which shone red, like a flame. The redness depended on the strength of the electrical current, which was influenced by speech. However, these components are outdated and there is therefore no cause to apply hav’ara to the process of sound amplification.
Similarly, contemporary microphones do not create sparks as a result of speech. If a spark is created at all, it is only at the time the instrument is turned on. Therefore, if the microphone is activated before Shabbat, or by an automatic timer on Shabbat, creation of sparks is not a relevant issue.
As for the inner workings of the microphone, even outdated coal-based microphones, there are still no sparks. Such microphones contain grains of coal which serve as electrical conductors. Speaking near the microphone changes, by means of a membrane, the density of the grains, and thereby the strength of the current. Instead of a steady direct current (DC) in the grains, the person’s speech changes the frequency of the current (in accordance with the frequency of the speech). Nevertheless, the current is constant and unbroken by a switch, and therefore no sparks are created. Similarly, more modern condensor microphones do not spark since they work on an alternating current (AC), and speech only changes the strength and frequency of the current.
The only hav’ara problem which can arise concerns microphones with a panel display, where the speech causes lights to go on (Such lights can be used either to create a sound-and-light effect for spectators, or to indicate the volume of the speech). There are also microphones, no longer commonly in use, where a green light burns brighter or duller depending on the strength of the electrical current into which the sound is converted. In these cases, there is indeed a problem, for they transgress the principle of “One who adds oil to a lamp is culpable for hav’ara.”
However, since these devices are no longer common, it would seem that we should not issue a blanket prohibition on all microphones lest someone come to use these.
In conclusion: it seems that the melachot of lighting and extinguishing a fire cannot serve as grounds to forbid the use of microphones on Shabbat.
All these prohibitions apply to turning an appliance on or off. However, if the appliance is already on, and all one does is change the strength of the current (e.g. adjusting the volume of a radio), there is clearly no “creativity” involved that can be considered building, fixing, or completing. Contemporary decisors have also written that molid does not apply to changing an existing current. (Of course, we are not discussing a case of changing the strength of a source of light or heat, since that is clearly hav’ara, as stated above.) The prohibition of creating a current, molid zerem, is derived from the prohibition of creating a scent, molid rei’ach (Beitza 22b, Shulchan Aruch OC 511:4). The gemara states, and the Magen Avraham codifies, that it is permissible to add scent to a scented garment on Shabbat; by the same token, adding to an existing current would not be considered molid.
The following is an excerpt from a previously unpublished article written by Rav Shlomo Zalman Auerbach zt”l in 5706 (1945-6) on the subject of radio broadcasts on Shabbat and Yom Tov. In it, he raises all the relevant problems regarding electricity on Shabbat, and rejects them one by one.
[These prohibitions] apply only to creating or breaking a circuit in a fan, refrigerator, etc. However, when one speaks into the microphone of a radio, no sparks are created, since the manufacturers [of the microphone] are very careful to avoid this. Therefore, even if there is a malfunction and a spark is created, no transgression is committed since it is merely a davar she-eino mitkaven (an unintended result). Thus, when one speaks into a [broadcast] microphone on Shabbat, he does not cause an act of lighting or extinguishing [a flame], or any other forbidden melacha. Rather, the speaker merely causes a change in current which affects the radio waves being broadcast, such that the membrane of the radio receiver vibrates in accordance with the sound waves of the speaker. It would therefore seem that there is no need whatsoever to be concerned with the problems of makkeh b’patish, tikkun mana, or molid, since his speech does not cause any Shabbat prohibition to be violated.
See also the Tzitz Eliezer (vol. 6, 6), who discusses the use of hearing aids on Shabbat (this issue will be dealt with later in this article). In the course of his discussion, he deals at length with the issues of boneh, metaken mana, and molid zerem, and concludes (ibid., section 13): “Therefore it seems that, in truth, one should not forbid speaking [on Shabbat into a hearing aid], for this does not violate boneh or molid.”
In conclusion, the commonly held assumption that microphones are forbidden on Shabbat due to the problem of electricity (like other appliances which are switched on and off) is fundamentally mistaken.
In the first responsum (Igrot Moshe OC 3:55), Rav Feinstein wrote: “One’s speech causes [the circuit] to contain more electricity, and it is possible that this is a melacha, for the nature of electricity has not been clarified.” In the second (OC 4:84), he elaborated: “The electric current increases according to the volume of the voice ... We can see this when we attach to the microphone another device measuring the current ... We [also] know that the microphone uses more electricity when someone is talking [into it] than it does when not in use. One who employs electricity on Shabbat may violate a biblical prohibition, even where there is no hav’ara; practically speaking, this matter requires thorough investigation.”
He added there, “The voice heard via the microphone is no longer the voice of the speaker, but rather an [electrical] impression of his voice ... This is a possible biblical prohibition - that his voice makes an impression on some component of the microphone. Despite the fact that this is not considered writing, for there are no letters, nevertheless there is reason to suspect a melacha [is involved], since something new has been created by means of which an amplified voice can be heard. Perhaps this violates makkeh b’patish or boneh; [the question of] the actual melacha involved must be analyzed.”
I have not merited to understand Rav Feinstein’s reasoning here, and he himself wrote that the matter was not entirely clear to him. It is true that speech affects the strength of the current in the microphone, and particularly in the amplifier, but this is merely a change in the current, not the creation of one. There is no closing of a circuit involved, nor any hav’ara, nor completion of a task, nor any lasting impression; I therefore see no room for his suspicions. Furthermore, we will later quote from Rav Feinstein’s own ruling on hearing aids, where he states that the suspicions of a prohibition are unclear, and therefore in cases of great need may be permissible.
The first (and seemingly only) person to analyze the different types of microphones in a halachic context was Rav Shlomo Goren zt”l in his article, “Use of a Loudspeaker on Shabbat on Navy Ships.” His conclusions relevant to our discussion are (p. 319): “Speaking into a dynamic microphone is forbidden rabbinically due to molid zerem (creating a current) on Shabbat. It is irrelevant whether the microphone was activated by a timer, since it is the actual speaking into the microphone which is forbidden, due to the creation of a new current caused by the sound waves striking the dynamo ... Speaking into the other two types of microphones (coal-based and condensor) - if they were turned on before Shabbat - is permissible for the sake of essential military functions.”
This is apparently the type of microphone referred to by Rav M. Roth zt”l (Kol Mevaser 2:25): “Regarding the question of installing a certain recently-invented type of microphone in a large synagogue ... I have determined that there is no basis whatsoever to permit this, since the uniqueness of this type of microphone lies in the fact that the speech itself creates the electrical energy.”
In summary: It is forbidden to use a dynamic microphone on Shabbat due to the prohibitions involved in creating a current. However, these prohibitions do not apply to coal-based or condensor microphones.
However, there are also amplification systems equipped with squelch mechanisms, which do not register sounds under a certain strength. In these systems, there is a danger that “environmental noise” will not affect the microphone, but speaking will “break through” the squelch barrier, thus closing a circuit and causing the microphone to function. Clearly, these systems are forbidden for use on Shabbat, due to the prohibitions of electricity involved.
I would also like to point out that for our purposes, it does not matter whether a microphone is connected to an amplifier by a cord or by a wireless connection. A wireless microphone communicates with an amplifier by means of a frequency broadcast from one antenna to another. When both the microphone and amplifier are in operation, the constant electronic frequency between them is modified by the speaker’s voice; but, as above, the speech does not create a new current.
The Tzitz Eliezer (vol. 6, 6:6) summarizes:
From all the above, it seems in my humble opinion that it should certainly be permitted for a hearing-impaired person to use a hearing aid on Shabbat, provided it is turned on before Shabbat. There is no room to innovate a decree of mar’it ayin (an appearance of transgression); [in other words, we should not worry] based on the fear that others will see the hearing aid and think that it is permissible to turn it on on Shabbat. Just as we do not concern ourselves with appearances when a light is turned on or off by a timer (which was set before Shabbat), [so too here].
In his Responsa Minchat Yitzchak (vol. 1, 37), Rav Yitzchak Weiss dealt only with the issue of carrying a hearing aid on Shabbat; it seems that it was obvious to him that the electrical issues posed no problem. (He quoted Rav Yosef Eliyahu Henkin’s Responsa Edut L’Yisrael to this effect.) Later (vol. 2, 17) he was asked specifically why it should not be prohibited due to electricity; in what sense does it differ from a microphone? He responded that it was “unclear (safek) in reality and unclear in Halacha” whether there is hav’ara in a microphone. Therefore, “regarding the issue of microphones, I decided according to the stringent opinions, so as not to lead to breaches in the wall of the House of Israel [since those who wanted to bring microphones into synagogues were adopting untraditional modes of worship]. But regarding hearing aids - since those who use them do not intend to cause breaches, but rather to protect themselves from road hazards [and the like] - I relied on the lenient opinions, thinking that they certainly clarified that in fact there is no ground for suspicion [of hav’ara], as long as it was turned on before Shabbat.”
Subsequently, Rav Weiss cites the concurring opinion of Rav Ovadia Yosef (Yabia Omer 1:19), who says that Rav Shlomo Zalman Auerbach explained to him that “speech does not create any sparks, but rather a mere increase in current. And therefore we must conclude that it is permissible for one who is hard of hearing to place in his ear a device that amplifies sounds (as long as it is turned on before Shabbat), since there is no problem in increasing the current.” Rav Weiss repeated this opinion later as well (Minchat Yitzchak vol. 2, 112).
Rav Zvi Pesach Frank, too, addressed only the issue of wearing a hearing aid, apparently assuming that electricity was not an issue (Har Zvi, OC 173).
Rav Yaakov Breisch (Chelkat Yaakov vol. 3, 186) also dealt with the question of the difference between a microphone and a hearing aid. He opined that microphones may not be used on Shabbat because of the prohibitions of mashmi’a kol (creating a sound) and shema yetaken (lest one repair), neither of which applies to a hearing aid. Furthermore, he asked, “Is it conceivable that if someone - Jew or Gentile - came to synagogue or to one’s house while wearing a hearing aid, that no one would be permitted to utter a sound in his presence? I believe that no one would forbid such a thing, since (unlike a loudspeaker) one does not speak directly into a hearing aid, but rather one speaks as usual and the hearing aid picks up the sound of his speech.” It is clear that Rav Breisch is concerned only with the problems of mashmi’a kol and shema yetaken (which we shall discuss in chapter 2), but not with the issue of electricity.
Similarly, Rav Moshe Feinstein (Igrot Moshe, OC 4:85) permitted the use of hearing aids on Shabbat, distinguishing (in terms of mashmi’a kol) between a loudly amplified sound and the lower volume of a hearing aid. “Since it is not clear which melacha this resembles, we cannot forbid [the use of hearing aids] for ill people and for a great need ... and the potential problem of utilizing electricity is not a clear prohibition, nor is it even a clear safek (doubt).”
Shemirat Shabbat K’hilchata (34:28) writes, “It is permissible for those who are hard of hearing to use an electric hearing aid on Shabbat, as long as it is turned on before Shabbat. Furthermore, it is permissible to adjust the volume on the hearing aid if no wires become red-hot.” He adds in the third volume (corrections and addenda), “Rav Shlomo Zalman Auerbach zt”l further stated that it is permissible to speak on Shabbat to a person wearing a hearing aid, for despite the fact that his speech affects the current in the hearing aid, nevertheless the change is miniscule even at the moment of his speech, such that even the Chazon Ish zt”l would not consider it boneh or soter (building or taking apart). However, the Chazon Ish’s opinion on the permissibility of a device where the changes occur in the wire carrying the current [i.e. where the wire reddens or brightens - Y.R.] is not clear to me.”
In other words, contemporary halachic authorities permit the use of hearing aids on Shabbat, and do not see any prohibition of electricity involved.
Rav M. Roth (Kol Mevaser, 2:25) wrote:
The responsum of the Maharil (221) codified by the Beit Yosef and the Darkei Moshe (YD 113), states that blowing with the mouth is [considered the same] as performing an action with one’s hands. The Beit Yosef writes, “I have found written that [one who] blows with his mouth prevents [the status of] bishul akum (gentile cooking) and it is considered as if [he cooked] with his hands. Proof can be adduced from Bava Kama (17b) where damage caused by kicking stones is considered to be like shooting an arrow, while blowing is considered like [damaging with] one’s hands. This is learned from the [case of a] rooster which sticks its head in a glass utensil and breaks it by crying out loud, where one must pay full damages (Bava Kama 18b). From here we see that kocho k’gufo (an act performed by strength of one’s actions, without actually touching the object, is considered to have been done directly).”
These proofs were also brought by Rav Shlomo Goren (Meishiv Milchama, p. 307), who further cited the statement of Rav Yosef (Bava Kama 18b), “[The owner of] a horse which neighed, or a donkey which brayed, and thereby broke a vessel, must pay half damages.” Rashi explains that these are cases akin to kicking stones, regarding which we learned that kocho k’gufo. Likewise, Rav Goren cited the Beit Yosef regarding bishul akum, adding, “It is irrelevant whether he blows with his mouth, with bellows or with a straw.”
Rav Goren also cited as proof the gemara in Bava Kama (60a) stating that if one fans a flame and is assisted by the wind, he is culpable if his fanning alone could have accomplished the damage. Similarly, he quoted the opinion of Rav Shimon ben Lakish in Shabbat (75b), “One who blows glass transgresses makkeh b’patish.” This is so, says Rav Goren, even if he blew the glass with a hand or foot-operated bellows. He concludes, “If one is culpable for wind created by his hands or feet, how much more so for wind blown by his mouth!”
The Minchat Yitzchak (vol. 2, 17) cites with regard to microphones the phrase, “By means of speech the action was performed.” Furthermore, he cites the ruling of the Minchat Yaakov that one is forbidden to blow dust off his wife’s clothes when she is nidda since kocho ke-gufo (and therefore it is like touching her), and compares it to fanning a flame (with regard to Shabbat or damages). He also quotes the Imrei Zvi (Bava Kama 17), who learned that blowing is considered an action from the prohibitions of lighting or extinguishing “by breath.”
There is a ruling of the Rema (OC 308:33) which seems to contradict this line of thought: “One may move an object which is muktza by means of blowing, for this is not considered regular carrying.” One might explain that blowing is considered to be an action on the part of the person, but that it is not the usual way of carrying and therefore muktza is permitted. However, I would like to suggest that breathing, and perhaps speaking, are considered to be the person’s action only if he grasped the object (e.g. if he held the microphone near his mouth), but not if he simply spoke and the sound was picked up by a nearby microphone. My proof is from a case of damages (CM 420:25): “A person who yelled in another’s ear and caused him to become deaf is not culpable according to human law, but is according to divine law. If he grabbed him and blew [a horn] into his ear, causing him to become deaf, he must pay full damages.” Further on (420:32), the Shulchan Aruch rules: “One who frightens his fellow without touching him (e.g. by shouting behind him), such that the fellow falls ill from fright, is not culpable according to human law, but is obligated according to divine law ... If he grabbed him and blew [a horn] in his ear, he is liable.”
What is the difference whether he grabbed him or not? The Sma (26) explains: “As long as he did not grab him in order to physically perform an act on him, it is considered merely a grama (indirect causation); nevertheless, he is obligated according to heavenly law, since [the damage] was brought about by him.” Subsequently (27), he quotes the Mordechai: “Even if he did not blow into his ear, but rather struck the wall near his head which caused him deafness - he is culpable [only] if he held him.”
In other words, all depends on whether he held him or not. Therefore, it seems to me that all the above cases where blowing is considered a direct action apply only if he was holding the person or object. However, if one performs an action with his mouth alone, or if he speaks before a microphone without holding it, why should we consider it an action?
Proof cannot be adduced against my assumption from the prohibition of driving one’s animal by voice on Shabbat (and similarly, driving an animal by voice to plow kilayim). In that case, no one would say that the voice pushes the animal; rather, the very definition of the prohibition is using one’s voice.
2) If the system is turned on before Shabbat, or on Shabbat itself by means of a timer, speaking into it on Shabbat poses no problem of molid zerem, or any other Shabbat prohibition. However, this does not apply to a dynamic microphone, which is prohibited on Shabbat.
3) One may not use a microphone with a squelch mechanism.
4) We will determine further that one should not hold the microphone in his hand, and should disable the on-off switch.
According to Rashi, mashmi’a kol does not belong to the category of melacha, but is rather for*bidden because it constitutes a sort of “weekday activity”(uvdin d’chol) and “denigration of Shabbat” (ziluta). So too wrote the Meiri: “This act creates noise and is widely known, which constitutes disrespect for Shabbat; but some permit even this.” In light of this, any activity which creates loud noise should be prohibited, due to disrespect for Shabbat. And in fact, this approach is quoted by the Darkei Moshe in the name of Mahari Weil: “One is forbidden to set on Erev Shabbat a clock [apparently a “grandfather” clock] which will make a loud noise on Shabbat, due to hashma’at kol.”
However, the Darkei Moshe also quotes the Agur, who permits setting a clock before Shabbat: “This is not similar to the sound of a water mill, since one hearing the noise of a water mill on Shabbat will think that the owner placed the grain in the mill on Shabbat itself; whereas regarding clocks, everyone knows that they are set the day before, and are not set on the day they chime.” According to this approach, the entire problem is that others will think that a forbidden action was performed on Shabbat.
The difference between these two approaches (namely, whether hashma’at kol is forbidden due to disrespect of Shabbat or the impression that a prohibition was violated) is expressed in a case where a loud noise is created, but it is clear that no prohibition was violated (such as the case of the grandfather clock).
The Shulchan Aruch (OC 252:5) permits “placing grain in a water mill just before dark.” The Rema writes, “We are not concerned with hashma’at kol, i.e. with the possibility that people may say that one’s mill is grinding on Shabbat. Some, however, forbid using a mill and [say] that we should always be concerned with hashma’at kol; and this is the preferable way to behave. But in a situation involving financial loss, we should be lenient, as was explained in chapter 244. Furthermore, one may set up a clock before Shabbat, even though it will sound the hours on Shabbat, for everyone knows that clocks are set in advance.” The Shulchan Aruch (OC 338:3) likewise maintains that a clock may be set prior to Shabbat; we will discuss his opinion further in section 3 of this chapter.
Thus, in summary, the Shulchan Aruch is not concerned with the problem of hashma’at kol at all with regard to the water mill and similar cases. The Rema clearly maintains (in chapters 252 and 244) that the reason to initially prohibit hashma’at kol is lest the listeners think that Shabbat was violated. Neither mentions the reason of “denigration of Shabbat.”
Rav Moshe Feinstein, too, in the previously mentioned responsa (OC 3:55 and 4:84), bases the prohibition of hashma’at kol only on the fear of creating an impression of Shabbat violation (as in the case of operating a water mill). “Since on regular weekdays, people plug in a microphone only when they need to speak, it is forbidden to turn on a microphone before Shabbat for use on Shabbat, since the listeners may think that it was connected to electricity immediately before prayer or the sermon. For the same reason, it is forbidden to turn on a television or radio before Shabbat for use on Shabbat.” In other words, there is no inherent problem with hashma’at kol on Shabbat, but rather we merely fear creating a mistaken impression.
Of course, Rav Feinstein did not mention the possibility of setting the microphone on a timer before Shabbat (what is popularly known as a “Shabbos clock”), in keeping with his general disapproval of the use of timers to perform melachot. Regarding heating food with a timer, he wrote (OC 4:60): “It is clearly forbidden, for by means of a timer one can perform all the melachot on Shabbat in all factories, and there is no greater denigration of Shabbat than this. It is clear that if this [timer] existed during the time of the Talmudic sages, they would have forbidden its use, just as they forbade telling a non-Jew [to perform melacha for you] for the same reason. And it is possible that [using a timer] is included in the prohibition of telling a gentile, for [the Sages] forbade all melacha performed on behalf of a Jew; how much more so by means of his own action [via the timer]!”
But doesn’t everyone set their house lights on timers before Shabbat? Rav Feinstein responds: “People have already become accustomed to turning off their lights by means of a timer, and one should not forbid turning the lights back on again via a timer, since it is customary to do this [turn lights on and off] also by means of a gentile. Therefore, even though it is preferable to be stringent [regarding gentiles], [timers] should not be prohibited, since their use is already common. But let us not add to this by permitting cooking and other melachot by means of a timer!”
It seems that this ruling by Rav Feinstein is not widely accepted among poskim, and it is customary today to use timers not just for lighting, but also for air conditioning, heating, watering, alarms, milking cows, etc. Everyone is aware that timers are commonly used, so there is no reason to fear that others will suspect that one is performing a melacha directly.
I have not succeeded in understanding this position, for the Shulchan Aruch does not mention the issues of “becoming known” and “weekday activity,” but rather only the issue of creating an impression of violation. In fact, in a case where it is known that the prohibited action was not performed on Shabbat - i.e. setting a clock - the Shulchan Aruch explicitly permits it (even though there is still an issue of avsha milta)!
Regarding activating a washing machine before Shabbat and having it continue working on Shabbat, Rav Ovadia Yosef (Yechaveh Da’at 3:18) cites the dispute among the Rishonim, and between the Shulchan Aruch and the Rema, about the water mill. He concludes that it should be permitted “in accordance with the Shulchan Aruch. But our brothers the Ashkenazim are stringent unless there is a special need for this.” He further adds that hashma’at kol is a problem of denigration of Shabbat.
I find this, too, difficult. Even the Rema does not side with Rashi that the issue is denigration of Shabbat, but rather only one of creating a mistaken impression (as is clear from his ruling regarding clocks). Rav Yosef is not dealing with the issue of mistaken impressions, since the washing machine operates for only a limited time; if it is still within the first hour of Shabbat, no one will suspect the owner of having turned on the machine during Shabbat. Why should this be any different than the case of the grandfather clock? Moreover, if one wants to claim that any noise creates denigration of Shabbat, then why is it permissible to use fans, refrigerators, air conditioners, etc.?
Additionally, if we wish to forbid the use of microphones due to “denigration of Shabbat” or “weekday activities,” then I see no reason not to forbid hearing aids for the same reason.
In summary, despite the fact that some have used the categories of “denigration” and “weekday activity” to forbid microphones, there seems to be no basis for their application. The Shulchan Aruch does not believe they are relevant (since he even permits using water mills right before Shabbat), and even the Rema seems not to apply them (since he permits setting a clock before Shabbat to chime on Shabbat). To my mind, the category of “avsha milta” does not seem to apply to hashma’at kol either.
A priori, one might have claimed that the prohibition of klei shir applies even when the music is heard without human effort, for example, a radio attached to a timer. The potential problem of adjusting a musical instrument applies just as much in this case. But both the Shulchan Aruch and the Rema explicitly permitted clocks which chime on Shabbat, which certainly fall under the category of klei shir. It seems that they believe that the decree covers only that which the rabbis mentioned specifically, namely, making music by means of human effort. We should refrain from extending the decree to other cases which we believe may lead one to adjust a musical instrument.
However, the Aruch Hashulchan (OC 338:5) believes otherwise: “It is also forbidden to set up a kli shir before Shabbat so that it will chime on its own on Shabbat. This stands to reason: since the decree is ‘lest one adjust a musical instrument on Shabbat,’ what difference does it make if the instrument plays by itself or by human effort? In either case, there is a danger that if it does not play well, he will adjust it on Shabbat.” He is hard-pressed to account for the permissibility of a chiming clock, and suggests that one is not interested in its pleasant musical qualities, but rather just in telling time. His distinction may or may not apply to musical chimes on a clock; but regarding speaking into a microphone, one certainly is not interested in “the pleasant sounds of a kli shir.” At worst, a microphone would fall under the same category as a chiming clock, which is permissible. Rav Shlomo Zalman Auerbach (Kovetz Ma’amarim, p. 42) rejects this opinion of the Aruch Hashulchan, stating that we do not have the authority to innovate new decrees. He also cites proof from the Shulchan Aruch Harav that one does intend to enjoy the music of a chiming clock.
Until now, we have seen that the Sages forbid actively using klei shir on Shabbat, lest one come to adjust them. However, Rav Moshe Feinstein (OC 3:55, 4:84) extended this reasoning to cover microphones as well: “The decree against using klei shir lest one adjust them applies [to microphones and loudspeakers] as well, for it is quite common for one to need to adjust it while speaking ... and it does not help if it is sealed in such a manner that one will not be able to adjust it, for what the rabbis have forbidden is forbidden in any case, even if one has created a situation where it is impossible to [gain access to] adjust it.”
It seems from his wording that the prohibition of klei shir itself applies to microphones, not merely that we learn from klei shir that anything requiring adjusting is forbidden (since we do not innovate decrees on our own). If so, then we should forbid hearing aids for the same reason; it too is a device for hashma’at kol! Rav Feinstein devoted a responsum (OC 4:85) to this question. He claims that mashmi’a kol and avsha milta apply only to a loud sound, whereas a hearing aid produces a small sound. However, the loudness factor has no relevance regarding the prohibitions of klei shir and shema yetaken. Nevertheless, a hearing aid is permissible, for “since it is only for the hearing-impaired, it is to be considered an uncommon case which the decree did not apply to; moreover, [the wearer has] a great need for it.” This fine distinction is problematic: do we permit using uncommon klei shir? And who determines what is uncommon?
In his Tzitz Eliezer (4:26), Rav Waldenberg also mentions the prohibition of klei shir (lest one adjust them) regarding microphones: “Many a time we have seen with our own eyes a microphone malfunctioning in the middle of a speech, requiring a technician to come and make wearisome corrections which a non-specialist is not capable of; in fact, there is almost no occasion where a malfunction does not occur in the course of a series of speeches.”
Rav Waldenberg then posits a distinction between the “user” of a microphone and of a hearing aid: “The speaker uses a microphone to amplify his voice, and the Sages have forbidden this, lest one come to adjust klei shir. But when one speaks to a person wearing a hearing aid, one speaks normally and cannot be considered the ‘user’ of a kli shir. Rather, the deaf person is considered the user, since he wants to be able to hear, and the decree of klei shir is not applicable to him because he performs no action at all.” This distinction, like the previous one, seems forced to me.
Rav Yaakov Breisch (Chelkat Yaakov 3:186) offers another reason for the permissibility of hearing aids: “Since the device is underneath his clothes and is not seen, we need not worry lest he forget and adjust it himself, just as we do not hesitate to use a light which was lit before Shabbat, despite the fact that during the week everyone is used to turning lights on as he enters a room and off as he exits. In general, we do not have the authority to innovate new decrees ... This differs from the case of a microphone, where it is almost impossible to use it without making adjustments which constitute a desecration of Shabbat; as we see commonly [that one must make frequent adjustments], and one cannot argue with reality.”
I do not understand his distinction regarding “shema yetaken,” but in any case he emphasizes the frequency of repairs needed. In my opinion, if the situation changes and frequent repairs are not required (as I believe is the case today), and given that the use of timers is widespread on Shabbat, it would seem that there is no room to apply “shema yetaken” anymore, nor should we create new decrees.
Rav Yitzchak Weiss (Minchat Yitzchak 3:38) also mentions that “A device specifically made for projecting sound, even if the sound is not music, is forbidden to use on Shabbat. This is based on the Rema’s ruling (OC 338:1) that a beadle may not summon people to synagogue on Shabbat using an instrument specifically made for that purpose; for this reason, the Beit Yitzchak forbids speaking on a telephone on Shabbat even if it does not ring.” He later clarifies that the decree of klei shir applies only if the sound of the instrument is heard, and not the original voice of the speaker. However, in our case, since it is clear that “it is not the voice of the speaker which is heard by means of a telephone or microphone, but rather another voice altogether,” these instruments are forbidden. In other words, in Rav Weiss’s opinion, a microphone is precisely the type of kli shir forbidden by the Sages. He also mentions that there is a real fear that one will come to repair it, since malfunctions are frequent.
Rav Weiss bases his view of the prohibition of klei shir on the Beit Yitzchak, who wrote (In the index to YD 31) regarding telephones, “Since the voice of the speaker is heard only by means of [electrical impulses] ... this is also considered mashmi’a kol by means of the device.” However, Rav Shlomo Zalman Auerbach (Kovetz Ma’amarim, p. 41) rejects this opinion:
[According to this,] it would be forbidden to speak to someone hard of hearing who is wearing a hearing aid. Furthermore, it would be forbidden to call such a person to the Torah, since the person reading the Torah certainly intends for the person receiving the aliya to hear him. Additionally, when the person himself says a blessing or Keriat Shema, [according to this logic] he would have to attempt to hear his own voice directly and not by means of the hearing aid - something which is extremely strange. But in my humble opinion, [speaking to someone with a hearing aid] is mere speech, and the decree of the Sages did not forbid normal speech. It is true that it is forbidden to make a voice heard on Shabbat by means of an instrument specifically made for this purpose, such as a record player; but the reason for this prohibition is that turning on the instrument on Shabbat is forbidden. If, however, the device was turned on before Shabbat, we have not found that the Sages forbade one to speak or sing only because his voice passes through the device and is then heard from a distance ... And despite the fact that there is a legitimate concern that one will adjust the device in order to be better heard, nevertheless in my humble opinion this [situation] is not included in the Sages’ decree. [Such a prohibition] would be like a new decree, and we should not add to [existing] decrees ... nor can we create new prohibitions not mentioned [by the Sages].
In conclusion: It is doubtful whether “shema yetaken” applies to microphones, since microphones seem not to fall under the category of klei shir and we should not create new decrees of our own. Furthermore, we can today create a situation where there will be no malfunctions or where access to the microphone in order to make repairs will be blocked.
The basis of the decree regarding the water mill is that people will suspect the owner of violating a biblical prohibition, namely grinding with a mill. Even according to the Magen Avraham’s opinion that grinding with a water mill is only a rabbinic prohibition, Rav Auerbach points out that essentially grinding is a biblical prohibition. He adds, “Similarly, [using a] microphone [gives the impression that one is violating a biblical prohibition,] since every time one turns it on or off he lights or extinguishes several lights.” He also compares it to setting a clock, which according to the Pri Megadim violates the biblical prohibition of makkeh b’patish.
I believe that according to the criteria mentioned by Rav Auerbach himself, we should no longer apply hashma’at kol to microphones. Firstly, today no microphone has lights connected to the amplifier. Secondly, any use of electricity is merely a rabbinic prohibition according to Rav Auerbach, and the decree only covers cases where one could suspect that a biblical prohibition was violated.
Rav Yisraeli later questions an inference made by Rav Moshe Feinstein (Igrot Moshe 3:58). Rav Feinstein noted that, since the Shulchan Aruch (OC 252) permits the use of a water mill, his ruling permitting the use of a chiming clock (OC 338) seems to be redundant. On the basis of this seeming redundancy, Rav Feinstein distinguished between objects which are in continuous activity, like a water mill, and those which only operate at intervals, like the chiming of a clock. In the former, there is no reason to suspect that the owner has violated Shabbat, since the sound of the mill can be heard continuously from before Shabbat. In the latter, however, there is reason to suspect that the owner set it on Shabbat, since it does not sound continuously. In line with this logic, Rav Yisraeli reasons that since we follow the Rema’s opinion that we are concerned about creating suspicion, and microphones fall into the latter category (where there are grounds for suspicion since it is not in continuous use), we should forbid the use of microphones.
However, Rav Yisraeli says that this distinction is unclear and uncodified. One should not build an entire edifice upon the fact that the Shulchan Aruch cites the case of the clock, since “the goal of the Shulchan Aruch is to be like a set table, ready for eating,” i.e. the goal is to be as comprehensive as possible. Therefore, there is no reason to forbid microphones.
In my opinion, we could answer Rav Feinstein’s question simply. The Shulchan Aruch finds it necessary to specifically permit the case of the clock since we may think that it is prohibited due to “shema yetaken,” as in the decree of klei shir. Therefore he informs us that since there is no action on Shabbat itself, but rather the clock is set before Shabbat, there is no problem.
Rav Yisraeli summarizes his opinion:
When the system is set up such that it is turned on and off by a timer ... and especially if the control panel is locked [so that one cannot gain access to repair it] ... it is permitted. There is no reason to be concerned about creating an impression of Shabbat violation, since use of timers is now widespread and well-known; this is no worse than a chiming clock ... For this reason we permit using a light which is switched on and off on Shabbat by a timer ... Likewise, the problems of avsha milta and ziluta d’Shabbat do not apply, since we have demonstrated that these pertain only where one creates a great noise (as the Tur states, “It becomes widely known”).
Rav Yisraeli formulated the following practical guidelines in this matter, to which I made some small additions. When I presented my conclusions to him in 5754, he wrote in the margin, “I concur with what is stated here.”
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Guidelines for the Use of Microphones and Amplifiers on Shabbat
1. One may not use a dynamic microphone (which creates current), but may use a condensor microphone (or a carbon-based microphone) which merely changes the strength of the current.
2. The microphone itself should not include an on-off switch. If such a switch exists, it should be electrically disabled.
3. One may not hold the microphone in his hand; it should be set up as a free-standing unit.
1. The system should be fully transistorized.
2. The system may not contain lights which turn on and off, or change their intensity, due to speech.
3. It is preferable for the system to work on battery power and not to be plugged into a power grid (in order to be sure that use of the system will not illuminate any bulbs).
C. Labels and Safety Measures
1. The system should be clearly labeled as operating in accordance with Halacha.
2. A timer should turn on the system at a pre-set time.
3. All buttons, dials, and switches (in the entire amplification system) must be covered, locked (including the timer) and inaccessible without a key.
4. The system should be set up such that, in case of a malfunction, it can be shut off in an indirect manner (gramma). In this case, one will not be able to reactivate the system until after Shabbat, and then only by unlocking the sealed control panel.
1. Use of the microp[hone is restricted to mitzva cases, and only where there is a great need.
2. One may not play klei shir over a microphone, even by means of a radio set on a timer, etc.
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... [Rav Yisraeli] certainly does not need my support ... But let me add an additional reason [to permit the use of microphones, contingent upon the stipulations above], which I dealt with at length in my book Mekor Chaim Hashalem (vol. 3, 106). The Chazon Ish (quoted at the end of Sefer Menucha Nechona and in the Tzitz Eliezer 4:31) permitted turning on sprinklers in one’s field or garden before Shabbat and letting them continue operating into Shabbat as much as needed ... In order not to arouse the suspicion of onlookers, he suggested that one affix a large sign stating that the sprinklers were turned on before Shabbat. Similarly, in our case, if one follows the guidelines (C.1) and places on the microphone a sign stating, “This system operates in accordance with Halacha,” and one takes into account Rav Yisraeli’s claim in his responsum (section 10) that “Use of timers is widespread and well-known” - then this ruling [that microphones are permissible in certain circumstances] is unanimous ...
At the behest of several Sefaradi rabbis in the diaspora, I also wrote to Rav Pinchas Baruch Toledano, a dayan in London, to ask his opinion. Some excerpts from his response follow:
... Upon examination, I find fit to permit your device for use on Shabbat and holidays for mitzva purposes, such as to enable congregants to hear a cantor’s prayer or a rabbi’s sermon. I will explain my conclusion briefly: this device does not create any sparks, but rather merely amplifies the voice of the speaker. Therefore, if it is in operation from before Shabbat, or if its operation is initiated on Shabbat by a timer, it is permissible. This resembles the gemara (Shabbat 17) cited by the Shulchan Aruch (OC 252) which permits one to initiate a melacha right before Shabbat, even if it
cannot be completed before the onset of Shabbat and instead concludes by itself on Shabbat ... since we follow Beit Hillel that we are not commanded to have our possessions desist from work on Shabbat (shevitat kelim). In all these cases, the Sages were not concerned that onlookers would think that a prohibition was violated (e.g. that one watered his field or spread his net on Shabbat), since certainly onlookers will realize that the action commenced before Shabbat. This too is the case with microphones, especially in an Orthodox synagogue, where undoubtedly all will know that it was set up with the approval of the rabbi and in accordance with Halacha.
Rav Yisraeli wanted to compare our case to that of the water mill ... about which the authorities were in dispute: the Shulchan Aruch (252:5) states that it is permitted, while the Rema took Tosafot’s opinion to heart and ruled that only in a case of financial loss should we be lenient The Rambam too did not mention the case of the water mill, which implies that he permitted it. Since the Shulchan Aruch ruled in accordance with two pillars upon whom all Israel rely, it is appropriate to permit the use of a microphone, at least in Sefaradi synagogues [since they follow the rulings of the author of the Shulchan Aruch]; [for these authorities] permitted even a water mill, whose sound is loudly heard. But in such a novel matter, it is appropriate to have a uniform ruling ...
But, truth be told, there is no need for all this. In my humble opinion, our case does not resemble a water mill at all. There, the sound is the product of the forbidden melacha of grinding, which the onlooker may think was initiated on Shabbat. But here, it is clear that the sound comes from the voice of the speaker, which is merely amplified by the device; what kind of denigration of Shabbat could this be? Furthermore, it seems to me that the considerations of avsha milta and ziluta d’Shabbat, mentioned by Rashi, do not apply in an Orthodox synagogue, for the congregants know that whatever the rabbi has sanctioned is in accordance with Halacha. But the sound of a water mill reverberates into the street, and there is certainly reason for the hearers to suspect that the grinding was initiated on Shabbat.
Rav Yisraeli also wrote that perhaps we can extend the Rema’s leniency in a case of financial loss to a case of mitzva as well ... But he was unsure about this extension, since it is possible that the Rema only intended to be lenient in cases which arise perchance, but not to institutionalize this leniency on a permanent basis. However, I think that the fact that the Rema wrote “in a case of financial loss” instead of his usual formulation, “in a case of great financial loss,” indicates that he is lenient even in a case of minimal financial loss. In my opinion, this is because he essentially agrees with the Shulchan Aruch that a water mill should be permissible, but nevertheless he took into account the authorities who are strict in this case. However, his stringency applies only where the action creates a loud noise and financially benefits the owner. In a case of a public mitzva, I believe even the Rema would admit that a microphone is permissible, for everyone knows that, since it is in a synagogue, it has been set up in consonance with Halacha. We know that there are many Godfearing people who put their lights on a timer before Shabbat, and no one suspects them of violating Shabbat ...
Likewise, the Rashbatz (Responsa, 2:167) ruled that ... where there are no grounds for suspicion, it is permissible ... And this is exactly the same as the consideration I mentioned before, namely, that in a synagogue there are no grounds for suspicion ... Similarly, Rav Chaim Pilagi (Lev Chaim 2:6) ruled on the basis of the Rashbatz’s opinion that non-Jewish workers may perform road work on the Jewish street [on Shabbat]. Since everyone knows that the non-Jews are contractors [and therefore can work whenever it is convenient for them], there is no suspicion [that they were hired to perform the work specifically on Shabbat]. The Nediv Lev (1:10) also supported the Rashbatz’s ruling. See the Sdei Chemed (Mem, 227) as well.
The Noda B’Yehuda (OC 1,12) wrote that even if there is no suspicion among the townspeople [due to the common knowledge of the circumstances], we should be concerned with arousing suspicion among visitors ... But I believe that the Rashbatz was not concerned with the issue of visitors. In any case, regarding a microphone in a synagogue, even the Noda B’Yehuda would admit that there are no grounds for suspicion among visitors. Anyone entering the doors of a traditional synagogue knows in advance that everything going on there is in strict accordance with Halacha, and therefore one will not come to suspect that Shabbat is being violated ...
Now, with your indulgence, I would like to make a small comment. The Rema (339:3) wrote that in our day, we are not expert at making musical instruments, and therefore we should not extend the decree of “shema yetaken” to uncommon cases. Consequently, it seems to me that your claim that “shema yetaken” applies to a microphone is incorrect. The decree is based upon the fear that one will forget that it is Shabbat, and will repair the instrument. However, in our case, this is inapplicable for two reasons. First, only a skilled technician can repair a microphone. Second, even if a technician is present, the congregation will undoubtedly remind him that it is Shabbat. The decree applies only to an individual; regarding a congregation, we believe that “the congregation remembers.”
To summarize: ... I concur with the gaon of our generation, Rav Shaul Yisraeli, that a microphone may be used on Shabbat for mitzva purposes, according to the guidelines you set forth ...
With best regards and Torah blessings,
Pinchas Baruch Toledano
The device consists of a container of compressed air and a system of pipes in which the compressed air flows. After one speaks into a horn-like input, his voice is carried on the stream of compressed air in the pipes. Acoustic adjustment (which apparently lies at the heart of the idea) then causes the voice waves to be amplified. Originally, the company had the sound flow into many small outlets (akin to earphones) placed near every seat or two. Currently, they are talking about having the amplified sound flow into a central outlet, akin to a loudspeaker.
Let me explain. We have shown that, given the current technology, the main problems with using a microphone on Shabbat have nothing to do with the fact that it runs on electricity. The problems concern the decree of klei shir, the fear that one will repair it, hashma’at kol like a water mill, avsha milta, denigration of Shabbat, and the suspicion of onlookers. Regarding all but the last of these, I see no difference between an air microphone and a regular microphone. In my opinion, an air microphone is a kli shir exactly like a shofar or trumpet; it creates a loud noise like a water mill; there exists the possibility that one will try to adjust it etc.. If you wish to claim that it is not a kli shir because it transmits speech; that we should not innovate a decree of “lest one repair it;” that it does not resemble a water mill because everyone knows that there is no Shabbat violation involved - then the same considerations should apply to a regular microphone as well. Only regarding the suspicion of onlookers might there be a difference between the two types of microphones; with an electric microphone, onlookers may think that an electric circuit was created on Shabbat. But we have already explained that even if one would turn on existing equipment on Shabbat, he would violate only a rabbinic prohibition, and we are not concerned with creating suspicion regarding rabbinic prohibitions. We also noted above that “everyone knows” that the equipment was turned on either before Shabbat or by means of a timer, and thus resembles a chiming clock (which is permitted).
I have heard that there are those who permit the air microphone since the speaker’s original voice is carried through the pipes (although clearly the majority of the sound waves reaching the audience’s ears comes from the air pumped by the compressor). I am astonished at this claim: even in an actual musical instrument (such as a trumpet) the player’s breath is mixed in, and nevertheless it is forbidden!
In many musical instruments, the sound comes mainly from an “echo chamber,” whose geometry shapes and amplifies the sound. To the best of my understanding, an air microphone operates on the same principle.
In my opinion, halachic definitions (in all fields) do not stem from scientific, physical, or technical definitions. The definitions of klei shir and hashma’at kol are not based on the technology of sound production, wave dispersion, or other acoustic considerations. The question at hand is whether these devices are included in the rabbinic decree of klei shir or not. In this regard, it does not matter whether one makes his voice heard by means of an electric or an air microphone.
Some of those who give a blanket permit to use an air microphone claim that it does not amplify the speaker’s voice, but merely carries it. On the basis of material I have received from the factory, I find this claim to be mistaken. Therefore, as far as klei shir and hashma’at kol are concerned, the two types of microphones are identical.
Even in an air microphone, it is not the speaker’s natural voice which reaches the listeners. His voice merely modulates the flow of compressed air within the system. It is true that speech in general operates on a similar principle, where sound waves create a ripple effect. But this has no relevance regarding the halachic definition of klei shir and hashma’at kol; these definitions do not relate to the way sound is propagated.
Rav Halperin also brought this proof from the Shevut Ya’akov (3:31): “ ... an instrument designed to carry sound several miles, allowing people distant from each other to communicate - can such a device be forbidden on Shabbat? We have never heard anything of the sort.” However, this quote has no relevance to us whatsoever. The Shevut Ya’akov is discussing the possibility of performing kiddush levana on Shabbat. Mahari Segal objected to this, since techumin (boundaries on Shabbat and holidays) apply vertically as well as horizontally, and “one should not greet the Shechina [which is] outside the techum.” In the course of refuting this opinion, the Shevut Ya’akov states that greeting someone outside the techum is not considered exiting the techum: “If someone sees his friend standing outside the techum, is it possible that it is forbidden to extend a greeting to him?” And then he makes the above-quoted statement, “And especially [if one speaks to his friend on the other side of the techum] by means of an instrument designed to carry sound ...” I highly doubt that the Shevut Ya’akov is addressing our issue; he is merely concerned with the theoretical option of communicating with someone outside the techum, in order to prove that such speech or sight is not considered exiting the techum. Clearly, we cannot learn anything about the permissibility of an air microphone from here.
Rav Halperin also cited Rav Shlomo Zalman Auerbach’s opinion that the prohibition of klei shir does not apply even to electric microphones, adding that air microphones are nevertheless preferable. However, I do not see why an air microphone is preferable regarding the decree of klei shir and hashma’at kol.
From a mistaken understanding of the technology, he then reaches a mistaken halachic conclusion: “It therefore seems that an air-pressure microphone is permissible, especially where there is a medical need for it or if it is being used for mitzva purposes. This is true even if it is used in an old age home or a hospital (where people cannot hear without amplification) to fulfill the mitzvot of kiddush, havdala, megilla, and shofar.”
I believe that it is a serious mistake to permit fulfilling the mitzvot of shofar and megilla by means of an air microphone, because the assumption that it is the original sound which is ultimately heard is false. Clearly, the sound produced by an air microphone is an echo, a modulated sound produced by the air compressor.
Rav Gedalyah Dov Schwartz of Chicago, Chairman of the Rabbinical Council of America’s Halacha Commission, also authored a responsum concerning the air microphone. Relying on Rav Halperin’s understanding of the microphone’s operation, he permitted it as well, stating that the integrity of the original voice is maintained despite the amplification, and therefore this bears no resemblance to the prohibited klei shir. As mentioned above, I disagree with this understanding of the air microphone; furthermore, what is the basis of his definition of klei shir?
To summarize: I see no difference between an electric and an air microphone regarding either klei shir or hashma’at kol; regardless of whether one permits or forbids, the two types of microphones should follow the same rule. Personally, I think they should both be permitted, since they should not be classified as klei shir. Nor can they be classified as being mashmi’a kol like a water mill, since everyone knows that they are set before Shabbat.
1. Regular amplification systems are not prohibited on Shabbat due to the use of electricity. This is not the case with dynamic microphones, or microphones equipped with lights or squelch mechanisms.
2. The main focus of discussions on the permissibility of microphones revolves around the issue of hashma’at kol like a water mill. The Shulchan Aruch permits the case of the water mill; and according to all opinions, it is permissible if “everyone knows” that it was not activated during Shabbat (and thus no one will suspect that a biblical prohibition was violated). Today, “everyone knows” that automatic timers are in widespread use, especially if the system is clearly labeled as such.
3. We may not innovate a decree of “lest one repair.” If we do, then we should prohibit the use of hearing aids and air microphones as well.
4. Since we permit setting a clock on Friday to chime on Shabbat, we see that we need not be concerned with avsha milta and ziluta d’Shabbat. For this reason, we permit using fans, air conditioners, etc.
5. Microphones and loudspeakers should not be defined as the types of klei shir which the Sages prohibited. If we do define them as such, then we must prohibit hearing aids and air microphones as well.
6. Rav Shaul Yisraeli published a comprehensive article permitting the use of microphones in synagogues on Shabbat, and other rabbis concurred with him.
7. The guidelines cited above solve the problems of malfunctions and public awareness.
8. Air microphones have no halachic advantage over electronic microphones, and they must be permitted or prohibited alike.
Such implements are sometimes used in telephones, though that too is becoming increasingly rare. Such microphones are insufficiently sensitive, and are therefore no longer used for music. See section 4 regarding the various types of microphones.
Beit Yitzchak, YD vol. 2, Hashmatot 31; Tzitz Eliezer vol. 1, 20:7 and 20:10; Rav Shlomo Goren, “Hadlakat HaChashmal B’Shabbat,” Sinai, Kislev 5709 and Shevat-Adar 5709; Rav Shlomo Zalman Auerbach, “Kovetz Ma’amarim B’Inyan Chashmal B’Shabbat;” and others.
The Zomet Institute designed an electric wheelchair for Shabbat use based on this principle. See the article by Yair Meir on this subject in Techumin 8 (p. 37ff.), and Rav Shaul Yisraeli’s responsum there written in response to Zomet. See also Prof. Zev Lev, “Molid Zerem Chashmali B’Shabbat,” Techumin 2 (p. 35ff.).
In my humble opinion, this conclusion can be disputed. As I shall make clear later, it can be argued that speech should not be considered an “action” with regard to prohibitions of Shabbat and damages; rather, only creating wind by means of an instrument is considered performing an action.
According to this logic, one would be responsible for fanning or extinguishing a flame only if he was holding the candle or torch, or if he fanned by means of a bellows (which certainly constitutes an action).
This container is filled by a compressor, which is permissible on Shabbat either because it operates only at fixed intervals (it has a special Shabbat attachment on the pressostat) or we rule leniently on the basis of the comparison to a refrigerator.
Bagpipes also operate on a similar basis: a person blows into a mouthpiece connected to a bag, and the air compressed into the space yields a sound. Bagpipes are mentioned in the Mishna (Keilim 20:2), and their operation is accurately described by Rav Ovadia MiBartnnura there.