Mishneh Torah — Shofar, Sukkah, Lulav הלכות שופר וסוכה ולולב, Chapter 1

מִצְוַת עֲשֵׂה שֶׁל תּוֹרָה לִשְׁמֹעַ תְּרוּעַת הַשּׁוֹפָר בְּרֹאשׁ הַשָּׁנָה שֶׁנֶּאֱמַר (במדבר כט א) "יוֹם תְּרוּעָה יִהְיֶה לָכֶם". וְשׁוֹפָר שֶׁתּוֹקְעִין בּוֹ בֵּין בְּרֹאשׁ הַשָּׁנָה בֵּין בְּיוֹבֵל הוּא קֶרֶן הַכְּבָשִׂים הַכָּפוּף. וְכָל הַשּׁוֹפָרוֹת פְּסוּלִין חוּץ מִקֶּרֶן הַכֶּבֶשׂ. וְאַף עַל פִּי שֶׁלֹּא נִתְפָּרֵשׁ בַּתּוֹרָה תְּרוּעָה בְּשׁוֹפָר בְּרֹאשׁ הַשָּׁנָה הֲרֵי הוּא אוֹמֵר בְּיוֹבֵל (ויקרא כה ט) "וְהַעֲבַרְתָּ שׁוֹפַר" וְכוּ' (ויקרא כה ט) "תַּעֲבִירוּ שׁוֹפָר". וּמִפִּי הַשְּׁמוּעָה לָמְדוּ מַה תְּרוּעַת יוֹבֵל בְּשׁוֹפָר אַף תְּרוּעַת רֹאשׁ הַשָּׁנָה בְּשׁוֹפָר:

It is a positive commandment from the Torah (Positive Commandment 170) and Sefer Hachinuch (Mitzvah 405) count this mitzvah as one of the 613 mitzvot of the Torah. to hear the sounding of the shofar, the Rambam himself writes that: "it is a positive mitzvah to blow the shofar on the tenth of Tishre... (Hilchot Shemitah V'Yovel 10:10)." on Rosh HaShanah, as [Numbers 29:1] states: "It shall be a day of sounding [the ram's horn] for you."The shofar, which is sounded both on Rosh HaShanah and for the yovel, is a bent 26b.) ram's horn. 16a states that a ram's horn is used to recall the akedah (binding) of Isaac. All shofarot other than that of a ram are unacceptable. 26b), who declares: "The mitzvah of Rosh Hashanah is to be performed with bent [shofarot]," implying the use of a sheep's or ram's horn for that is their natural shape.The Ra'avad, Rabbenu Asher, and many other Rishonim maintain that Rav Levi desired to designate the type of shofar which is most preferable to use, but did not intend to disqualify the horns of other animals. Their view is accepted by the Shulchan Aruch (Orach Chayim 586:1), which states that it is desirable to use the horn of a ram. However, if that is not possible, the horn of any animal may be used. The only exceptions are the horns of a cow and some wild animals whose horns are single, solid entities (Ramban).Even though the sounding of the shofar on Rosh HaShanah is not explicitly mentioned in the Torah [it was derived by our Sages in the following manner]. Concerning the yovel, [Leviticus 25:9] states: "You shall make a proclamation, sounding the shofar... you shall proclaim with the shofar." The oral tradition 33b explains that just as the "sounding" required by the Torah in the yovel requires a shofar, so, too, the "sounding" on Rosh HaShanah requires a shofar. is carried out with a shofar, that same instrument is used on Rosh HaShanah.

בַּמִּקְדָּשׁ הָיוּ תּוֹקְעִין בְּרֹאשׁ הַשָּׁנָה בְּשׁוֹפָר אֶחָד וּשְׁתֵּי חֲצוֹצְרוֹת מִן הַצְּדָדִין. הַשּׁוֹפָר מַאֲרִיךְ וְהַחֲצוֹצְרוֹת מְקַצְּרוֹת שֶׁמִּצְוַת הַיּוֹם בְּשׁוֹפָר. וְלָמָּה תּוֹקְעִין עִמּוֹ בַּחֲצוֹצְרוֹת מִשּׁוּם שֶׁנֶּאֱמַר (תהילים צח ו) "בַּחֲצֹצְרוֹת וְקוֹל שׁוֹפָר הָרִיעוּ לִפְנֵי הַמֶּלֶךְ ה'". אֲבָל בִּשְׁאָר מְקוֹמוֹת אֵין תּוֹקְעִין בְּרֹאשׁ הַשָּׁנָה אֶלָּא בְּשׁוֹפָר בִּלְבַד:

In the Temple, 4:1.) However, in the present context, it refers to the Temple alone. Thus, Rosh HaShanah 27a states that the shofar was sounded in this manner only "on the Temple Mount and at the eastern gate." on Rosh HaShanah, they would blow [the shofar in the following manner]: There was one shofar and two trumpets, [one on either] side. The sounding of the shofar was extended, while that of the trumpets was shortened, because the mitzvah of the day is performed with the shofar. 26b contrasts the sounding of the shofar and trumpets on Rosh HaShanah with their being blown on a fast day declared because of unfavorable conditions. On the latter occasion, the sounding of the trumpets was emphasized in keeping with the instructions of Numbers 10:9.Why were the trumpets sounded together with it? Because [Psalms 98:6] states: "You shall sound trumpets and the voice of the shofar before God, the King." 27a states that the expression "before God" implies: in the Temple. However, in other places on Rosh Hashanah, only the shofar is blown.

שׁוֹפָר שֶׁל עַכּוּ"ם אֵין תּוֹקְעִין בּוֹ לְכַתְּחִלָּה וְאִם תָּקַע יָצָא. וְשֶׁל עִיר הַנִּדַּחַת אִם תָּקַע בּוֹ לֹא יָצָא. שׁוֹפָר הַגָּזוּל שֶׁתָּקַע בּוֹ יָצָא שֶׁאֵין הַמִּצְוָה אֶלָּא בִּשְׁמִיעַת הַקּוֹל אַף עַל פִּי שֶׁלֹּא נָגַע בּוֹ וְלֹא הִגְבִּיהוֹ הַשּׁוֹמֵעַ יָצָא וְאֵין בַּקּוֹל דִּין גֵּזֶל. וְכֵן שׁוֹפָר שֶׁל עוֹלָה לֹא יִתְקַע בּוֹ וְאִם תָּקַע יָצָא שֶׁאֵין בַּקּוֹל דִּין מְעִילָה. וְאִם תֹּאמַר וַהֲלֹא נֶהֱנָה בִּשְׁמִיעַת הַקּוֹל. מִצְוֹת לֹא לֵהָנוֹת נִתְּנוּ. לְפִיכָךְ הַמֻּדָּר הֲנָיָה מִשּׁוֹפָר מֻתָּר לִתְקֹעַ בּוֹ תְּקִיעָה שֶׁל מִצְוָה:

At the outset, we should not blow a shofar of idol worship. However, if one sounded it, one has fulfilled his obligation. explains that this refers to a shofar belonging to a gentile that was used in the worship of idols, or a shofar which was itself worshiped as an idol. However, as will be explained, if the shofar of idol worship belonged to a Jew or if it was made from the horn of an animal that was sacrificed to an idol, even after the fact, its use is not acceptable. [In contrast,] should one sound a shofar belonging to an apostate city,, Chapter 4.) one has not fulfilled one's obligation. 28a explains that the difference between a shofar of idol worship and one of an apostate city is that all the property within the latter must be destroyed. Since ultimately this shofar must be burnt, even before it is actually destroyed it is no longer considered to be an existent entity. Thus, we may not use it on Rosh HaShanah, because a shofar used for the mitzvah must be of a specific size - slightly larger than one's hand, as mentioned in Halachah 5 - and a nonexistent entity has no size at all.A shofar of idol worship must also be destroyed. However, should the gentile negate its connection to idol worship before it is acquired by a Jew, it need not be destroyed, as stated in Hilchot Avodat Kochavim 8:8. Since there is a possibility that it will not have to be destroyed, it is considered to be an existent entity and may be used for the mitzvah.This principle applies only to aspects of idol worship belonging to a gentile. It is impossible to negate the connection between an idol worshiped by a Jew and its forbidden nature. (See Hilchot Avodat Kochavim 8:9.) Hence, a Jew's shofar of idol worship may not be used. Similarly, if a Jew has acquired a shofar of idol worship that belonged to a gentile before the latter negated its connection to idol worship, the Jew is no longer capable of negating this connection. Therefore, such a shofar may not be used on Rosh HaShanah.Also, once an animal has been sacrificed to an idol, there is no possibility of negating its connection to idol worship. Hence, its horn may not be used as a shofar.The Shulchan Aruch (Orach Chayim 586:3-4) quotes all the above laws as halachah. The Ramah relates that certain authorities recommend not using even a gentile's shofar of idol worship unless we know that he negated its connection with idol worship before Rosh HaShanah begins.Concerning a stolen shofar: 6:7), this case is an exception... one who blows it fulfills his obligation, because the mitzvah is only to listen to the sound, even though the listener does not touch [the shofar] 1:6) does not accept this view. or lift it up. The laws of theft do not apply to sound alone. cite other examples from Nedarim 13b-15a, where the Sages differentiate between sound and material entities.The Jerusalem Talmud (Sukkah 3:1) derives this law as follows:Everyone agrees that a stolen lulav is unacceptable. What is the difference between a shofar and a lulav?Rabbi Yosse responded: "Concerning a lulav, [Leviticus 23:40] states: 'You shall take for yourself,' implying that only 'your own' is acceptable. In contrast, [Numbers 29:1] states: 'It shall be a day of blowing for you,' implying that regardless [of the nature of the shofar used, the blowing shall be 'for you']".Rabbi Eliezer explained: "There, [concerning the lulav,] one must perform the mitzvah with the lulav itself. Here, [concerning the shofar,] one performs the mitzvah with its sound."Nevertheless, because a sin is associated with this mitzvah, Ashkenazic custom is that no blessing should be recited before blowing such a shofar (Magen Avraham 586:4).Similarly, a shofar from an olah offering should not be sounded, offering, no part of its body may be used any other purpose. Therefore, we should not use such a shofar from such an animal for any purpose whatsoever.This halachah applies before the blood from the sacrifice has been offered on the altar. Afterwards, the skin and horns of the animal become the property of the priests and may be used for mundane purposes (Rashi, Rosh Hashanah 28a). but 5:16, the Rambam writes:Concerning the sound, sight, and smell of consecrated objects: We should not derive benefit from them. However, all the implications of the prohibition against using them for mundane purposes do not apply. if one sounds it, he fulfills his obligation, because the laws of מעילה do not apply with regard to sound alone. If you ask: "Behold, he has derived benefit from hearing [the shofar's] sound?"). Accordingly, the Rambam explains: - mitzvot were not given for our benefit., ibid.) states: "the mitzvot were not given to the Jewish people for their enjoyment, but rather as a yoke."This concept has relevance in the ethical, as well as the halachic sphere. In the tenth chapter of Hilchot Teshuvah, the Rambam writes:One who serves [God] out of love occupies himself with the Torah and the mitzvot...for no ulterior motive, not because of fear that evil will occur, nor in order to acquire benefit...The great Sages would command the more understanding and brilliant among their students in private: "Do not be like servants who serve their master for the sake of receiving a gift. Rather, since he is the Master, it is fitting to serve Him"; i.e., serve [Him] out of love.The above is not intended to imply that a person should not feel happy and fulfilled in the service of God. Quite the contrary; indeed, the Rambam concludes these halachot (Chapter 8, Halachah 15) with a description of the importance of happiness in the service of God. However, the intent is that the happiness should be a byproduct and not the goal of the service. We should be totally committed to fulfilling God's will, and the expression of that commitment should generate satisfaction and joy.Based on this concept - that mitzvot were not given for our benefit;a person who vows not to derive benefit from a shofar may use it to blow the teki'ot required to fulfill the mitzvah. - Doing so is not considered a violation of his vow.The Shulchan Aruch (Orach Chayim 586:5) advises that the person who took the vow should not blow the shofar himself [because many consider that to be a pleasurable experience (Taz)]. Rather, he should hear the teki'ot from a colleague.Also, the Shulchan Aruch (ibid.) notes that if a person specifically states that he vows not to listen to a colleague's teki'ot, he may not hear that person blow the shofar on Rosh HaShanah, because a vow (neder) can also negate a mitzvah. (See Hilchot Nedarim 3:6-8.)Based on this concept, a person who vows not to derive benefit from a shofar may use it to blow the teki'ot required to fulfill the mitzvah.

שׁוֹפָר שֶׁל רֹאשׁ הַשָּׁנָה אֵין מְחַלְּלִין עָלָיו אֶת יוֹם טוֹב וַאֲפִלּוּ בְּדָבָר שֶׁהוּא מִשּׁוּם שְׁבוּת. כֵּיצַד. הָיָה הַשּׁוֹפָר בְּרֹאשׁ הָאִילָן אוֹ מֵעֵבֶר הַנָּהָר וְאֵין לוֹ שׁוֹפָר אֶלָּא הוּא אֵינוֹ עוֹלֶה בָּאִילָן וְאֵינוֹ שָׁט עַל פְּנֵי הַמַּיִם כְּדֵי לַהֲבִיאוֹ. וְאֵין צָרִיךְ לוֹמַר שֶׁאֵין חוֹתְכִין אוֹתוֹ אוֹ עוֹשִׂין בּוֹ מְלָאכָה. מִפְּנֵי שֶׁתְּקִיעַת שׁוֹפָר מִצְוַת עֲשֵׂה וְיוֹם טוֹב עֲשֵׂה וְלֹא תַּעֲשֶׂה וְאֵין עֲשֵׂה דּוֹחֶה לֹא תַּעֲשֶׂה וַעֲשֵׂה. מֻתָּר לִתֵּן בְּתוֹכוֹ מַיִם אוֹ יַיִן אוֹ חֹמֶץ בְּיוֹם טוֹב כְּדֵי לְצַחְצְחוֹ. וְלֹא יִתֵּן לְתוֹכוֹ מֵי רַגְלַיִם לְעוֹלָם מִפְּנֵי הַכָּבוֹד שֶׁלֹּא יִהְיוּ מִצְוֹת בְּזוּיוֹת עָלָיו:

Regarding a shofar to be used on Rosh HaShanah: It is forbidden to violate the festival laws to obtain it. This applies (forbidden labor) prohibited by the Torah, but even when the forbidden practice is in the category of sh'vut. 21:1, the Rambam defines sh'vut as a prohibition instituted by the Sages because a particular activity resembles one forbidden as a melachah by Torah law, or because performing it may cause one to perform a melachah.Though these prohibitions are of Rabbinic origin, the Sages reinforced the power of their decrees and equated them with Torah law. Hence, just as one may not violate a melachah forbidden by the Torah to obtain a shofar, so, too, it is forbidden to violate a sh'vut forbidden by Rabbinic law (Kessef Mishneh). [Nevertheless, note the clarification of this principle in Chapter 2, Halachah 6.]How is the above exemplified? If there is a shofar in a treetop or across a river - and that is the only shofar available - one may not climb the tree or swim across the water to bring it. 32b) mentions other examples of forbidden activities. Needless to say, we may not cut the shofar [from the animal's head] or perform a forbidden labor [to prepare a shofar so that we may blow it]. [The rationale for the above is:] Blowing the shofar fulfills a positive commandment, while [the observance of] the festivals fulfills both a positive and a negative commandment. 1:2, the Rambam writes:Whoever rests from a melachah categorized as "work" on one of [these days] fulfills a positive commandment, because the Torah describes them as "days of rest"... if one performs a melachah that is not intended to prepare food,... one negates the performance of a positive commandment and transgresses a negative commandment, as [Leviticus 23:8] states: "You shall not perform any servile work." The observance of a positive commandment does not negate the observance of both a positive and negative commandment. 3b), that applies only when the negative commandment is not reinforced by a positive commandment, as in the case at hand.It is permitted to rinse a shofar with water, wine, or vinegar in order to improve its tone. 4:8.) However, this activity is not placed in that category (Rabbenu Manoach). However, as an expression of deference, one should never use urine [for that purpose], lest one view the mitzvot in a deprecating manner. (14:16):...lest one view the mitzvot in a deprecating manner, because the deference is not to be granted to the mitzvot in and of themselves, but to the One who commanded us to fulfill them, blessed be He.

שִׁעוּר הַשּׁוֹפָר כְּדֵי שֶׁיֹּאחֲזֶנּוּ בְּיָדוֹ וְיֵרָאֶה לְכָאן וּלְכָאן. נִסְדַּק לְאָרְכּוֹ פָּסוּל. לְרָחְבּוֹ אִם נִשְׁתַּיֵּר בּוֹ כַּשִּׁעוּר כָּשֵׁר וּכְאִלּוּ נִכְרַת מִמְּקוֹם הַסֶּדֶק. נִקַּב אִם סְתָמוֹ שֶׁלֹּא בְּמִינוֹ פָּסוּל. סְתָמוֹ בְּמִינוֹ אִם נִשְׁתַּיֵּר רֻבּוֹ שָׁלֵם וְלֹא עִכְּבוּ הַנְּקָבִים שֶׁנִּסְתְּמוּ אֶת הַתְּקִיעָה הֲרֵי זֶה כָּשֵׁר. קְדָחוֹ בְּזִכְרוּתוֹ כָּשֵׁר שֶׁמִּין בְּמִינוֹ אֵינוֹ חוֹצֵץ. דִּבֵּק שִׁבְרֵי שׁוֹפָרוֹת עַד שֶׁהִשְׁלִימוֹ לְאֶחָד פָּסוּל:

The minimum size of a shofar is [a measure] sufficient that one may hold the shofar in one's hands [with the ends] visibly [protruding] on either side. 26a defines this measure as "an expanded handbreadth." The Beit Yosef notes that, in this context, a handbreadth is defined as four thumbbreadths. Thus, the difference between the width of a thumb and the other fingers accounts for the "expansion." In modern measure, a handbreadth is considered between 8 (Shiurei Torah) and 9.6 (Chazon Ish) centimeters.Should a shofar be cracked lengthwise, it is unacceptable. 27b. The Rabbis have noted that, in contrast to a crack along the shofar's width, in this context no minimum figure is mentioned with regard to the portion of the shofar remaining uncracked. Two contrasting interpretations are offered to explain the difference.Some maintain that as long as the entire length (or the majority of the length) of the shofar is not cracked, the shofar is not disqualified. Others maintain that even the slightest crack along the length of the shofar disqualifies it, because the pressure of the blowing will cause the crack to grow until, ultimately, the entire shofar will be cracked (Rabbenu Asher; Shulchan Aruch, Orach Chayim 586:8).Concerning halachah l'ma'aseh, both the Shulchan Aruch HaRav (586:8) and the Mishnah Berurah (586:43) write that when no other shofar is available, one may rely on the first opinion. Nevertheless, even the latter opinion does not disqualify a shofar that is cracked lengthwise if it is tied firmly so that the crack will not expand, or if the shofar is heated and the crack closed. Some opinions also allow such a shofar to be used if the crack is plugged closed with other substances. Should it be cracked along its width ibid., 9), - if a measure equivalent to the minimum size of a shofar remains,). However, the Ba'al Ha'itur maintains that a shofar is acceptable even if the minimum measure remains only from the crack to the end of the shofar. it is kosher., ibid.). It is considered as if it were cut off at the place of the crack.[Regarding a shofar with] a hole: If it was plugged 3:5), the Rambam writes that the hole must be plugged. This point is not accepted by the Shulchan Aruch (ibid., 7), which emphasizes that if the hole is not plugged, the shofar is kosher even though its sound has changed. Nevertheless, the Ramah states that if another shofar is available, a shofar with a hole should not be used. with another substance, it is unacceptable. If it was plugged with its own kind, it is kosher [under the following conditions]:the majority of the shofar remained whole;the plugging of the holes did not alter its sound. 27b. Rabbenu Asher interprets the passage differently. The Shulchan Aruch (ibid.) favors the Rambam's interpretation, but states that under difficult circumstances, when no other shofar is available, one may rely on Rabbenu Asher's interpretation.If one [merely] perforated the insides of the horn, [but did not remove them,] it is kosher, because a substance of the same kind is not considered an intervening entity. (ibid., 586:15) quotes this law, but also adds that if one removed this tissue from the horn and then hollowed it out, the tissue would be unacceptable for use as a shofar. Should one stick together fragments of shofarot until one has constructed a shofar, it is unacceptable. 27a explains that this construction is not called a shofar. The Shulchan Aruch (ibid., 10) states that this law applies even if the fragment of the shofar closest to one's mouth is of sufficient size to be considered a kosher shofar itself.

הוֹסִיף עָלָיו כָּל שֶׁהוּא בֵּין בְּמִינוֹ בֵּין שֶׁלֹּא בְּמִינוֹ פָּסוּל. צִפָּהוּ זָהָב מִבִּפְנִים אוֹ בִּמְקוֹם הַנָּחַת פֶּה פָּסוּל. צִפָּהוּ מִבַּחוּץ אִם נִשְׁתַּנָּה קוֹלוֹ מִכְּמוֹת שֶׁהָיָה פָּסוּל וְאִם לֹא נִשְׁתַּנָּה כָּשֵׁר. נָתַן שׁוֹפָר בְּתוֹךְ שׁוֹפָר אִם קוֹל פְּנִימִי שָׁמַע יָצָא וְאִם קוֹל חִיצוֹן שָׁמַע לֹא יָצָא. הִרְחִיב אֶת הַקָּצָר וְקִצֵּר אֶת הָרָחָב פָּסוּל:

If one made any addition to a shofar 586:11). - whether of its kind or from another substance - it is unacceptable.Should one coat it with gold from the inside or at the mouthpiece, it is unacceptable. 26b mentions that the mouth of the shofar used in the Temple was coated with gold, the place where the person blowing would put his mouth was not covered. Should one coat it on the outside: If its sound is changed from what it was originally, it is not acceptable. from being acceptable. If its sound did not change, it is kosher. (Orach Chayim 586:16).Should one place one shofar within another: If one hears the sound of the inner shofar, one has fulfilled one's obligation. 586:20) emphasizes that one may fulfill one's obligation under such circumstances only if the sound of the inner shofar remains totally unchanged. The teki'ot are unacceptable if its sound is altered. If one hears the outer shofar, one has not fulfilled one's obligation.. The Torah commanded us to hear one shofar and not two (Tosafot, Rosh Hashanah 27b).Should one widen the narrow portion of the shofar and narrow its wider end, the shofar is unacceptable. 27b explains the derivation of this law as follows: The terminology which Leviticus 25:9 uses when commanding us to blow the shofar, שופר והעברת, has an additional implication. That expression is also related to the word עבר, meaning "to pass." The manner in which we use the shofar must parallel the manner in which the ram passes by with it on its head.Based on the same principle, our Sages (ibid.) explain that a shofar is unacceptable if it was heated to the point that the horn became soft, and then turned inside out.

הָיָה אָרֹךְ וְקִצְּרוֹ כָּשֵׁר. גֵּרְדוֹ בֵּין מִבִּפְנִים בֵּין מִבַּחוּץ אֲפִלּוּ הֶעֱמִידוֹ עַל גִּלְדּוֹ כָּשֵׁר. הָיָה קוֹלוֹ עָב אוֹ דַּק אוֹ צָרוּר כָּשֵׁר שֶׁכָּל הַקּוֹלוֹת כְּשֵׁרִין בְּשׁוֹפָר:

If a shofar was long and one shortened it, 586:63). it is kosher. 27b explains that the necessity of mentioning this law arises from the last clause of the previous halachah. Since we find that the Torah requires us to use the shofar in the same manner as which it was carried by the ram, a special teaching is necessary to inform us that a shofar is acceptable even if it was shortened.The Kessef Mishneh explains that such a shofar is acceptable even it was shortened because of a disqualifying factor which it possessed on the portion which was cut off. If one scraped away the horn - either from the inside or from the outside - even if one did so to the extent that all that remained was the thin external shell, 586:13; Mishnah Berurah 586:65). it is kosher.Regardless of whether [the shofar's] sound is heavy, thin, or raspy, translate צרור as "dry," explaining that blowing a shofar causes it to dry out and produce a raspy tone. Hence, it was customary to rinse it with water or wine, as mentioned in Halachah 4. it is kosher, because all the sounds produced by the shofar are kosher.

הַתּוֹקֵעַ בְּתוֹךְ הַבּוֹר אוֹ בְּתוֹךְ הַמְּעָרָה. אוֹתָן הָעוֹמְדִים בְּתוֹךְ הַבּוֹר וְהַמְּעָרָה יָצְאוּ. וְהָעוֹמְדִים בַּחוּץ אִם קוֹל שׁוֹפָר שָׁמְעוּ יָצְאוּ. וְאִם קוֹל הֲבָרָה שָׁמְעוּ לֹא יָצְאוּ. וְכֵן הַתּוֹקֵעַ לְתוֹךְ חָבִית גְּדוֹלָה וְכַיּוֹצֵא בָּהּ. אִם קוֹל שׁוֹפָר שָׁמַע יָצָא וְאִם קוֹל הֲבָרָה שָׁמַע לֹא יָצָא:

When a person sounds a shofar within a pit or within a cave, those standing within the pit or cave fulfill their obligation. Concerning those standing outside: If they hear the sound of the shofar, they fulfill their obligation. If they hear the sound of an echo, they do not fulfill their obligation.Similar principles apply regarding one who blows into a giant barrel. If he hears explains that the Rambam does not mention people standing within a barrel, because that is a very unlikely eventuality. the sound of a shofar, he fulfills his obligation. If he hears an echo, he does not fulfill his obligation. 587:1 explains that this concept is also relevant for synagogues with poor acoustics. If the people hear echoes together with the shofar's sound, they do not fulfill their obligation.At present, there is a more common application of this principle. A person who hears the shofar through a microphone does not fulfill the mitzvah. In addition to the difficulties involved with the use of the microphone on a festival, there is a more essential problem. The listeners are not hearing the sound of the shofar, but rather a second sound, produced by a different mechanism. The microphone converts the sound waves of the shofar to electronic signals; these are then amplified and converted to a different set of sound waves. Hence, by hearing such a sound, we cannot fulfill the mitzvah obligating us to hear a shofar's call.