1) The first Posuk of Krias Shema should be said out loud. (This is especially important for the Shliach Tzibbur who must say it loud so the congregation can say it together with him at the same time, and accept the yoke of the Hashem’s Kingdom, together. See Levush Siman 61:26)
Some Poskim maintain that the entire Krias Shema (not just the first Posuk) should be said out loud. Even if not said very loud, it definitely should not be said in an almost inaudible whisper.
2) The Posuk "Baruch Shem K’Vod Malchuso L’Olam VaEd", which is recited immediately after the first Posuk of Shema, should be said in a whisper. ( See Mishna Berura Siman 61:30 for an explanation based on Yaakov Avinu and the Shevatim)
When reciting Krias Shema without a Minyan, Rav Chaim Solveitzik Zatzal of Brisk used to say "Baruch Shem" out loud, as he was of the opinion that the problem of saying it out loud was only when it is recited with a Minyan. (He obviously maintained the other reason, that the heavenly angels will be jealous of us saying such an exalted praise, and not the reason of the Mishna Berura above. See Shu"t Teshuvos V’Hanhagos from Rav Moshe Sternbuch Shlita Vol. 2 Siman 46)
Thank you again for the wonderful halachos.
I just want to check:
you wrote: "If one started Shemona Esrei when not needing the bathroom, and during Shemona Esrei the urge arose, he/she should not interrupt the davening, rather finish then use the restroom"
If one started Shemona Esrei not needing the bathroom but suddenly urgently does need to go - should he pause, go and then resume davening where he left off?
My Answer:
What I wrote is that the Halacha allows them to finish Shemona Esrei even though the urge to use the restroom arose during their davening. However, if the urge arose so badly that he/she cannot concentrate and quickly finish the shemona Esrei, then indeed they can (and probably should) stop in middle and use the restroom.
If they resume davening in less time than it would take to daven the entire Shemona Esrei, they can resume where they left off. If more time elapsed, Shemona Esrei should be started again from the beginning.
Our holy sages, the Chazal tell us תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן עולם הבא, שנאמר הליכות עולם לו, אל תקרי הליכות אלא הלכות
- one who studies [at least two] Halachos daily is assured a portion in Olam Haba - the world to come.
(:מגילה כ"ח )