Rosh Hashanah 34B

תשע תקיעות בתשע שעות ביום ⁠— יצא.

the requisite 9 shofar blasts at 9 different times of the day, he has fulfilled his obligation, as the blasts need not be heard in immediate succession.

תניא נמי הכי: שמע תשע תקיעות בתשע שעות ביום ⁠— יצא. מתשעה בני אדם כאחד ⁠— לא יצא. תקיעה מזה ותרועה מזה ⁠— יצא. ואפילו בסירוגין, ואפילו כל היום כולו.

This is also taught in a baraita: If one heard 9 shofar blasts at 9 different times of the day, he has fulfilled his obligation. If one heard the blasts from 9 different people simultaneously, he has not fulfilled his obligation. If one heard a tekia from this one and afterward he heard a terua from this other one, he has fulfilled his obligation, as one does not have to hear all the blasts from the same individual. And this is true even if one heard the blasts from the different individuals at intervals, and even if it took the course of the entire day.

ומי אמר רבי יוחנן הכי? והאמר רבי יוחנן משום רבי שמעון בן יהוצדק: בהלל ובמגילה, אם שהה כדי לגמור את כולה ⁠— חוזר לראש! לא קשיא: הא דידיה, הא דרביה.

The Talmud asks: And did R' Yoḥanan actually say this? Didn’t R' Yoḥanan say in the name of R' Shimon ben Yehotzadak: During the reading of hallel or the Megilla of Esther, if one paused long enough to complete all of it, he must return to the beginning, as it must be read in one session? Why is the halakha different in the case of the shofar? The Talmud answers: This is not difficult, as this ruling with regard to the shofar is his own opinion, and that case of hallel and the Megilla is his teacher’s opinion. It is R' Shimon ben Yehotzadak who holds that one may not pause in the middle of sounding the shofar.