Berakhot 149

4:
The idea that upon hearing or seeing something that is religiously exciting and meaningful we should recite a berakhah is attributed by the Gemara [Berakhot 54a] to Yitro, Zipporah's father, Moses' father-in-law. Exodus 18 describes how, a few weeks after their escape from Egypt, the Israelites reached Mount Sinai and there make camp. Yitro takes this first opportunity to accompany his daughter and grandchildren to their reunion with Moses. (Moses had left Zipporah and the children with Yitro in Midian for safety's sake, before returning to Egypt on his mission.) The Torah describes how Moses recounts to his father-in-law all that had happened to him and his people since he and Yitro had last seen each other – how God had rescued them from Egyptian slavery and from the Pharaoh's army. We then read Va-yiĥad Yitro [Exodus 18:9]. This phrase is susceptible of several interpretations. Rashi, in his famous comment on the word, says that there is here, in Hebrew, a play on words, and that the phrase means that Yitro come out in goose bumps because of his enthusiastic excitement. This enthusiasm led him to say "Praised be God Who has rescued his people…" [Exodus 18:10].

More concerning the responses to berakhot. I wrote as a comment on something that Richard Friedman had written: if you wish to be yotzé on the berakhah you are hearing (that is, if you wish to respond to it 'Amen' and have it considered as if you, too, had recited the berakhah) – then you must not respond 'barukh hu i-varukh shemo', because, as Richard says, this is considered an interruption if you are not a "bystander" but a "principal".

Adena Galinsky asks:

If this is the case, then when and why is it permitted to say it at all? When the shaliach tzibur is leading the davening, aren't we all expecting to have it considered as if we too had recited all the berachot which s/he utters?

I respond:

We are confusing two responses here. With one exception that we have mentioned previously, Amen should be said whenever one hears a berakhah made by someone else (including the Sheli'aĥ-Tzibbur), and most certainly we must do so when that person has recited a berakhah as our agent. We should not respond barukh hu u-varukh shemo when that response would constitute a halakhic interruption. If I am listening to someone make Kiddush and intend their berakhah to include me, then I should not respond barukh hu u-varukh shemo and must respond Amen. If I make the first response I shall be interrupting the berakhah and thus excluded myself, and if I omit the second response I have not included myself. Conversely, if I intend making Kiddush for myself, then I should make both the first and second responses.

Nowadays, the task of the cantor in most cases is not to make people yotzé, since they have, for example, already recited their (silent) Amidah; so during the repetition of the Amidah they should make both responses.

Rémy Landau writes in the same matter:

If we have to think about when to utter the phrases which sanctify the holy name, then we may as well forget the religion. Because as you've demonstrated through an interesting discussion, the matter is far too complex for anyone to properly do the responses. I myself, even after having been told that it is inappropriate to do the baruch hu… at some moments in the services can't help myself from doing so. Would I be wrong in noting that there are absolutely no penalties whatever to those who say amen and baruch hu at moments deemed to be inappropriate by those who wish to show that they know too much? I hope so, because I would like to continue to see our devotion as a matter of spiritual expression, and not as some kind of cerebral exercise which can only be mastered by an elite few… such as chess.

I respond:

I don't buy any of this! First of all mitzvot tzerikhot kavvanah: mitzvot that are performed without thinking about what one is doing are no mitzvah, so a modicum of intellectual involvement is an absolute necessity so that their performance is that of a mitzvah and not a mere ceremonial rigmarole. Secondly, I am certain that anyone who is capable of mastering the intricacies of e-mail and computerized electronic communication will have very little difficulty in asking himself for one second "what is the status of this berakhah?" After all, very quickly it can become a routine.

The penalty for answering barukh hu u-varukh shemo where not appropriate is, as I have already stated, that it is as if the mitzvah has not been fulfilled at all. That's all! Spirituality in Judaism is expressed primarily in the fulfillment of the mitzvot.