Stolen scroll

To the Rabbi
Peace and blessings
I hope I'm not bothering you…. I tried searching the site to see if the Rabbi had already answered the following question and I couldn't find it….
I am trying to clarify the issue of a stolen scroll that was ruled out in Shua's Exodus, and this is from Teshuvah Har-Rashba, who likened it to a shofar.
What I'm trying to understand is:
Why is it that even with the shofar, on the one hand, they emphasize hearing the sound of the shofar, and so it seems that this is the mitzvah of hearing the sound, and on the other hand, they do concern themselves with who blows the trumpet, not being a minor or a woman, meaning someone who is obligated in something or who intends to blow the trumpet to fulfill an obligation, etc.
Why, if they say that the mitzvah is hearing the voice, do they still require all sorts of restrictions regarding the form of the takiya?
In the law of the shofar itself, I can understand that the shofar's flaws are related to the desired sound, and if the shofar is cracked, even though a shofar sound is emitted, it is not the sound we are referring to.
But for fence bears to poke and poke, I don't understand why this is necessary.
And I am not asking from the essence of the mitzvah that it is hearing the sound, but rather as a contradiction, what is the idea that allows hearing the sound of a stolen shofar because the mitzvah is hearing the sound and at the same time requires boundaries for the one blowing it?
I think this is a fairly fundamental question in understanding the mitzvah of Shofar Medila and other mitzvahs.
Thank you very much.