Amplified Sound Waves
Question: Can one fulfill a mitzvah which involves hearing something recited
or read, e.g., hearing Havdalah or the reading of the Megillah, by hearing
the words over a telephone or from the loudspeaker of a public address system?
Discussion: The answer to this question, extensively debated by the poskim,
depends on the halachic interpretation of certain technical facts. Both the
telephone and the public address system “transform” sound waves in air,
e.g., spoken words, into an electrical current within the instrument, and,
ultimately, back into sound waves. It is debatable, though, how the halachah
views these sound waves: 1) Are they an extension of the speaker’s voice,
merely amplified or carried to a distance that the unassisted human voice
cannot reach; or are they 2) distinct from the speaker’s voice, since the
loudspeaker or receiver “creates” new sound waves from something—an
electrical current, which is not sound?
Translated from technical into halachic terms, the question is whether the
mitzvah in question can be fulfilled only with the authentic, original voice
of the speaker, or also by means of sounds generated by electrical impulses
derived from the original voice and occurring simultaneously with it.
Some earlier authorities were of the opinion that the sound heard over the
telephone or from the loudspeaker is the original speaker's voice. It is
permitted, therefore, in their opinion to listen to the Megillah read
over a public address system or to Havdalah over the telephone.
Other authorities maintained that the halachic view of amplified sounds
is difficult to resolve and cannot be clearly decided. Thus in their opinion
it remains questionable if mitzvos can be performed by means of a public
address system or telephone. It follows, therefore, that only under
extenuating circumstances—when no other possibility exists—is it permitted
to fulfill a mitzvah by means of a loudspeaker or telephone.
However, the majority of the authorities who have studied this issue,
including Rav S.Z. Auerbach who researched it extensively with the aid
of a team of technical experts, have ruled conclusively that the sound
waves emitted by a loudspeaker or telephone receiver are definitely not the
speaker’s original, authentic voice. In addition, they rule unequivocally
that one’s obligation cannot be discharged by hearing an electrically
generated sound even if the original speaker’s voice is heard
simultaneously. Accordingly, one cannot fulfill a mitzvah by listening to
sound waves from a microphone or a telephone.
In practice, therefore, it is clear that when another possibility exists,
mechanical voice amplifiers should not be used to fulfill a mitzvah. For
example, a woman who is home alone and has no one to make Havdalah for her
should rather recite Havdalah herself than listen to it being recited by
someone else over the telephone. Even if she cannot or will not drink wine,
grape juice, or beer, it is preferable for her to recite Havdalah over
coffee, tea (with or without milk), or milk alone (and,
according to some poskim, undiluted grapefruit, orange or apple juice
as well) than to listen to Havdalah recited over the phone
If one finds himself in a situation where otherwise he cannot recite
Havdalah or hear the Megillah at all, e.g. in a hospital, and there is no
one who can come until Tuesday evening to make Havdalah for him, he may
have to rely on the poskim who permit listening to blessings, etc., over the
telephone. But in a situation where someone could come and recite
Havdalah for him before Tuesday evening, the correct procedure is to wait
until then for Havdalah to be recited. If he is weak, he may eat before
hearing Havdalah. If he is not weak, and he anticipates that he would be
able to hear Havdalah before chatzos Sunday, he should refrain from eating
A related issue is whether or not it is permitted to answer Amen to a
blessing or Kaddish heard over a microphone, telephone, or during a live
telecast transmitted by satellite. Some poskim permit this and do not
consider the answering of Amen etc., to be l’vatalah (“for nothing”), since
they remain undecided about the halachic status of amplified sound waves, as
explained above. In addition, some poskim permit it, based on the
ancient precedent set in the great synagogue in Alexandria, where most
people did not hear the blessings being recited because of its vast size,
but were nevertheless permitted to answer Amen when signaled to do so by the
waving of a flag.
Rav Auerbach, though, rejects this comparison and rules clearly that it is
prohibited to answer Amen upon hearing a blessing in this manner. He agrees,
however, that one who is in the vicinity of the speaker, even though he
hears the speaker’s voice only over a microphone, etc., is permitted to
answer Amen, as was the case in Alexandria where everyone was inside the
shul and part of the congregation that was davening.
1. Minchas Elazar 2:72; Minchas Aharon 18 (quoted in Tzitz Eliezer 8:11).
2. Their argument is based partially on the fact that sound waves—even
without being mechanically transmitted—are carried through the air before
they are heard by the listener. The fact that the microphone amplifies those
sounds and furthers their distance should not be considered halachically
3. Rav T. P. Frank (Mikraei Kodesh, Purim 11 and in Minchas Yitzchak
2:113); Igros Moshe, O.C. 2:108; O.C. 4:126. [See, however, Igros Moshe,
E.H. 3:33 and O.C. 4:84.] Rav Y.E. Henkin (Eidus l'Yisrael, pg. 122) also
does not render a clear decision on this issue. See also Minchas Shelomo 1:9
quoting an oral conversation with the Chazon Ish.
4. Igros Moshe, O.C. 4:91-4 (and oral ruling quoted in Kol ha-Torah, vol.
54, pg. 18); Tzitz Eliezer 8:11. See also Shevet ha-Levi 5:84.
5. Da'as Torah, O.C. 689:2; Gilyonei ha-Shas, Berachos 25a; Eretz Tzvi
1:23; Kol Mevaser 2:25; Mishpatei Uziel 1:5; 1:21; Minchas Yitzchak 1:37,
3:38; She’arim Metzuyanim b'Halachah 129:25; 193:6; Yagel Yaakov, pg. 280,
quoting Rav Y.S. Elyashiv and Rav C. Kanievsky; Kinyan Torah 1:75; Yechaveh
Da’as 3:54; Moadim u'Zemanim 6:105. See also Teshuvos P’eas Sadcha 1:126 who
quotes a similar ruling from Rav C. Soloveitchik.
6. Minchas Shelomo 1:9.
7. Rav Auerbach and Yechaveh Da’as opine that those poskim who dissented
from this ruling were not familiar with the relevant technology.
8. Rav Auerbach makes clear that the same ruling applies to
hearing-impaired individuals who cannot hear without a hearing aid. Igros
Moshe, O.C. 4:85 is hesitant over whether a hearing aid works exactly like a
9. Women are obligated to recite Havdalah and may recite it themselves.
Although there is a well-established custom that women do not drink the wine
from the Havdalah cup, this custom is discounted when a woman needs to
fulfill her obligation of Havdalah; Mishnah Berurah 296:35; Aruch
10. Instant or brewed (Rav S.Z. Auerbach, Shemiras Shabbos K'hilchasah 60,
11. The tea or coffee should be cooled off enough to drink at least 1.6
fl. oz. within 3-4 minutes.
12. Aruch ha-Shulchan 272:14; Igros Moshe, O.C. 2:75.
13. Tzitz Eliezer 8:16; Shemiras Shabbos K'hilchasah 60:5.
14. If a woman refuses to recite Havdalah on her own and there is no one
available to recite it for her, her husband (or another man or woman) may
repeat it for her, even if he has already fulfilled his obligation earlier;
see Mishnah Berurah 296:36; Aruch ha-Shulchan 296:5; Da’as Torah 296:8; Ben
Ish Chai, Vayeitzei 22. The blessing over the candle, though, should be
omitted, in the opinion of several poskim.
15. O.C. 299:5.
16. Igros Moshe, O.C. 4:91-4; Tzitz Eliezer 8:11.
17. In this case, one should specifically not listen to Havdalah over the
phone, since then it may not be repeated for him when the visitor comes.
18. Mishnah Berurah 296:19, 21. Rav Y.S. Elyashiv, too, is quoted (Yad
le-Yoledes, pg. 135) as ruling that it is better to eat before Havdalah than
to listen to it over the telephone.
19. Igros Moshe, O.C. 4:91-4.
20 Yechaveh Da'as 3:54.
21. See Succah 51b and Tosafos, ibid.
22. See Halichos Shelomo 1:22-15.
Weekly-Halacha, Text Copyright © 2012 by Rabbi Neustadt, Dr. Jeffrey Gross and Torah.org.
Rabbi Neustadt is the Yoshev Rosh of the Vaad Harabbonim of Detroit and the Av Beis Din of the Beis Din Tzedek of Detroit. He could be reached at firstname.lastname@example.org