התוקע בתוך הבור או בתוך המער' אותם העומדים בתוך הבור והמער' יצאו והעומדים בחוץ אם קול שופר שמעו יצאו ואם קול הבר' שמעו לא יצאו וכן התוקע לתוך חבית גדולה וכיוצא בה אם קול שופר שמע יצא ואם קול הבר' שמע לא יצא:

If one sounds the shofar in a pit or cave, those standing in the pit or cave fulfill their obligations. Concerning those who stand outside, if they hear the sound of the shofar, they fulfill their obligation. If they hear the echo, they do not fulfill their obligation. Similarly, if one sounds the shofar into a large barrel or something similar, those who hear the sound of the shofar fulfill their obligation and those who hear the echo do not.

If one begins sounding the shofar in the pit and then ascends out of the pit and finishes the sounding, they fulfill their obligation, as everything that was heard, inside and out, was the sound of the shofar. Rema: The same applies to those who were in the pit at the beginning of the sounding (Gemara).

3. One who hears part of the soundings in a non-obligated fashion and part of it in an obligated fashion, or one who tells somebody unintentionally sounding a shofar "Intend to fulfill my obligation" who then proceeds to blow for the minimal length, neither of these fulfills their obligation. There are those who say that they fulfill their obligation if there is a minimal length of sounding in a state of obligation. Rema: The law is the same if one heard part of the sounding via echo, like if the blower was in a pit and the hearer was outside and in the middle of the sounding, the blower exited (Tur).