1. Baruch Hu Uvrach Shemo:
A. The Mitzvah:
Any time one hears any blessing the custom is to recite Baruch Hu Uvaruch Shemo. This is a custom and was not instituted by the Sages. [The saying of Baruch Hu Uvaruch Shemo has high mystical intent.]
Is one to answer Baruch Hu Uvaruch Shemo every time he hears Hashem’s name mentioned?
Some Poskim rule one is to answer Baruch Hu Uvaruch Shemo every time he hears Hashem’s name mentioned, even not in a blessing. Other Poskim rule that it is only answered when mentioned in a blessing, and so is the custom.
Is one to answer Baruch Hu Uvaruch Shemo in Birchas Kohanim?
Some Poskim rule one is to answer Baruch Hu Uvaruch Shemo upon hearing Hashem’s name in Birchas Kohanim. Other Poskim however rule one is not to answer Baruch Hu Uvaruch Shemo [and so is the custom of many].
Is one to answer Baruch Hu Uvaruch Shemo when hearing the blessing of Mitzvah or Birchas Hanehnin that he is not being Yotzei?
Some write that the custom is not to be particular to answer Baruch Hu Uvaruch Shemo for Birchas Hamitzvos or Birchas Hanhenin being that at times people hear these blessings in order to fulfill their obligation, in which case it is forbidden to answer it. Accoridngly, the main time for answering Baruch Hu Uvaruch Shemo is by Birchas Hashcar, Chazaras Hashatz, and by an Aliyah.
Is one to answer Baruch Hu Uvaruch Shemo to Birchas Hatorah of an Aliyah?
If the person is saying the blessing quickly and answering Baruch Hu Uvaruch Shemo will cause one to miss the conclusion of the blessing, what is he to do?
In such a case it is better that he be quiet and not answer Baruch Hu Uvaruch Shemo, than to answer it and miss the conclusion of the blessing and end up saying Amen right after saying Baruch Hu Uvaruch Shemo.
Pronouncing the words properly:
One must be careful to recite each one of the words Baruch Hu Uvaruch Shemo properly. One is not to swallow any of words or connect them, such as to say Baruchu Uvaru Shemo, [or Berich Shemo] and the like. One is to be careful to recite the words immediately after hearing Hashem’s name and not while Hashem’s name is still being said.
B. Answering Baruch Uvaruch Shemo when one is in middle of Davening:
One who is in an area of Davening in which it is forbidden to make an interval, which is from Baruch Sheamar in Pesukei Dezimra until after Shemoneh Esrei, then he may not answer Baruch Hu Uvrach Shemo to a blessing. [This applies even between the Perakim during Pesukei Dezimra. One may not answer Baruch Hu Uvaruch Shemo even between Yishtabach and Yotzer.]
Must one answer Baruch Hu Uvaruch Shemo if he is in the midst of learning Torah?
One who is in the midst of learning Torah is not obligated to answer Baruch Hu Uvrach Shemo [or Amen] when he hears Hashem’s name in a blessing.
C. Answering Baruch Hu Uvaruch Shemo to a blessing that one is being Yotzei:
In all situations that one hears a blessing and has in mind to fulfill his obligation through hearing it, such as by Kiddush or Havdala, and blessings said over fruits and over the Mitzvos, he is not to answer Baruch Hu Uvrach Shemo [upon hearing Hashem’s name said in the blessing].
Bedieved: In the event that one said Baruch Hu Uvaruch Shemo to a blessing that one is hearing to be Yotzei, it is possible that even Bedieved he does not fulfil his obligation of the blessing. For this reason it is imperative to warn the public of this matter, as many are unaware of this and incorrectly answer Baruch Hu Uvaruch Shemo. [Thus, if one said Baruch Hu Uvaruch Shemo by the blessing he is to try to hear the blessing again from another person. In the event that he cannot hear the blessing again from another person, he nevertheless fulfills his obligation of the blessing. He is not to repeat the blessing even without Sheim Umalchus.]
 Admur 124/2 and 8; Ketzos Hashulchan 22/5
 Admur 124/8; Michaber 124/5; Levush 124/2; Tur 124 in name of Rosh 4/19
Other opinions: Some Gedolei Yisrael avoided saying Baruch Hu Uvaruch Shemo when hearing Hashem’s name recited in a blessing. [Gr”a in Maaseh Rav 43; See Piskeiy Teshuvos 124 footnote 101] Others are accustomed not to answer it during Chazaras Hashatz in order not to make an interval in the blessing and treat it similar to Shemoneh Esrei. [See Peas Sadcha 19; Shulchan Hatahor 124/7; Chazon Ish; Piskeiy Teshuvos ibid]
 The reason: This wording is in light of the verse “Ki Sheim Hashem Ekra Havu Godel Lelokeinu”, that when one mentions Hashem’s name one is to give praise to Hashem. Furthermore, even when one mentions a Tzaddik of flesh and blood one is required to bless him as the verse [Mishlei 10/7] states”Zecher Tzaddik Levracha” that one you remember a Tzaddik you must bless him [Admur ibid]
 Admur ibid; Rishon Letziyon on Brachos 63 “It is thus not an obligation from the letter of the law”
 See Kaf Hachaim 5/12; Maaseh Rokeiach; Makor Chaim of Chavos Yair 124
 Elya Raba 124/9; Shiyurei Kneses Hagedola 128 Hashmatos; Birkeiy Yosef 124/7; Yosef Ometz 296 in name of Chareidim 4/17; See Poskim in next Q&A; See Ashel Avraham of Butchach 124
 Makor Chaim of Chavos Yair 124/5; Tehila Ledavid 124/3 in name of Dvar Shmuel 295 and that so is the custom; Magen Giborim 124/11; Piskeiy Teshuvos 124/11
 Shiyurei Kneses Hagedola; Peri Chadash 124/5; 128/13; Kaf Hachaim [Falagi] 15/76]; Ben Ish Chaiy Tetzaveh 15; Kaf Hachaim 124/27 that so is custom; See Ashel Avraham of Butchach 124 that this is done only by Nesias Kapayim to show the love for the Mitzvah
 Shalmei Tzibur p. 145 that so is implied from Dvar Shmuel 295, brought in Kaf Hachaim ibid; See Poskim in previous Q&A!
 See Piskeiy Teshvos 124/11
 Mishneh Halachos 13/16
 Piskeiy Teshuvos 124 footnote 106
 Yifei Laleiv in Yosher Leivav 5; Kaf Hachaim 124/28; Shaar Hatziyon 124/24
 Chesed Lealafim 124/4; Kaf Hachaim 124/29
 Makor Chaim 124; Piskeiy Teshuvos 124/11
 Admur 124/2 in parentheses; 124/8; M”A 124/9
 The reason: As Baruch Hu Uvrach Shemo is a mere custom and was not instituted by the Sages. [Admur 124/8] It is therefore not considered part of the blessing [Admur 124/2] and is thus forbidden to say it in middle of Davening in any area that one may not make an interval for a mundane matter, even in those areas that it is permitted to stop and answer Amen, such as in Pesukei Dezimra. If however one is holding in an area of Davening that it is permitted to make an interval for even mundane matters then it is permitted to stop and answer Baruh Hu Uvaruch Shemo. [Admur 124/8 and 2]
 Admur ibid “In any area that one cannot stop for a Davar Reshus”; P”M 124 A”A 9
 Tehila Ledavid 124/4 that so is implied from Admur ibid, however he questions why this is the case and that seemingly one should be permitted to make an interval between Yishtabach and Yotzer to say Baruch Hu Uvaruch Shemo, just like one may stop for a Mitzvah and to say Yisbareich Veyishtabach.
 Divrei David 41; Mayim Rabim 2; Pischeiy Teshuvah; Kaf Hachaim 124/25
 Ashel Avraham 215; Orchos Chaim 124/6; Toras Chaim Sofer 66/8 that one who is involved in a Mitzvah is exempt from a Mitzvah; Divrei David 41; Mayim Rabim 2, brought in Kaf Hachaim 124/25; Shevet Halevi 9/43; Tzitz Eliezer 11/4; Salmas Chaim 62; Kinyan Torah 2/36; 4/9; Pischa Zuta 5; Teshuvos Vehanhagos 2/73-74; Yabia Omer 9/3; Shearim Hametzuyanim Behalacha 20/3; Piskeiy Teshuvos 51/11 and 55/29 and 215/4
Other opinions: Some Poskim rule one is obligated to answer Amen even if he is in the midst of learning Torah, unless one learns like Rashbi and Toraso Umenuso. [Pischeiy Teshuvah brought in Kaf Hachaim 124/25]
 Admur 124/2 in parentheses and 192/2; Dvar Shmuel 295; Shoshanim Ledavid Brachos 8/8; Degul Merivava on M”A 124/9; Mateh Yosef 124/2; Kitzur SHU”A 6/9; Birkeiy Yosef 213/3 “Best to be stringent”; Chayeh Adam and other Achronim brought in M”B 124/21; Kaf Hachaim 124/26; See Shraga Hameir 5/55; Piskeiy Teshuvos 585 footnote 29; 124/11 footnote 106; Mishneh Halachos 13/16
Other opinions: Some Poskim rule one may answer Baruch Hu Uvarach Shemo even if he plans to fulfill his obligation with the blessing. [Maaseh Rokeaich 1/11, brought in Kaf Hachaim ibid; Birkeiy Yosef ibid “One is not protest against those who are accustomed to do so”]
 The reason: Whenever a person is hearing a blessing with intent to fulfill his obligation, such as by Kiddush, Havdala and blessings over fruits and Mitzvos, he may not answer Baruch Hu Uvaruch Shemo, being that one who hears [and fulfills his obligation] is like one who is saying it himself and it is forbidden to make an interval in the midst of a blessing. [Admur 124/2 in parentheses]
 Admur ibid; Chayeh Adam brought in M”B 124/21; See Shraga Hameir ibid that in such a case he also missed the words “Elokeinu Melech Haolam” of the person saying the blessing; See Minchas Elazar 1/20
Other opinions: Some Poskim rule that if one answered Baruch Hu Uvarach Shemo he nevertheless fulfills his obligation. [Conclusion of M”B ibid; Mahram Shick 51; Birkeiy Yosef 213/3 in name of Mahrash Abuhav; Piskeiy Teshuvos 124/11 and 585/3]
 The reason: It is possible that even Bedieved one does not fulfill his obligation as since he made an interval between Hashem’s name and Malchus with words that were not instituted by the Sages, he has therefore swerved from the dialect of the blessings that was set by the Sages. [Admur ibid in parentheses]
 Ketzos Hashulchan 22 footnote 11
 Ketzos Hashulchan 22 footnote 11
The reason: As Admur writes “it is possible that he does not fulfill his obligation” and we always rule in a case of doubt that Safek Brachos. [ibid]
 Ketzos Hashulchan ibid
The reason: Although in general we rule that whenever there is a Safek of blessings one should repeat the blessing without Sheim Umlachus, nevertheless, here he is not to repeat it as a) If he is doing a Mitzvah after the blessing, saying a blessing without Sheim Umalchus would be an interval between the original blessing that he heard, and was possibly Yoztei with, and the Mitzvah. Furthermore b) Saying Baruch Hu Uvaruch Shemo in between the Sheim and Malchus is certainly no worse than saying a blessing without Sheim Umlachus all together and hence there is no advantage for one to say it. [ibid]