I've tried to break down each word and particle to decipher the meaning myself since I think that'd be the best way to fully grasp it. Of course it'd still be great to get a second more professional opinion on the subject.
So far I've got it down to "I stop because the voice of my heart is crying."
I know that 誰 usually means who but is more commonly used to refer to a person rather than a direct translation to who, though I couldn't find something to back up that it could refer to ones self.
Right after that it says “が止める” which I figure should stay right after "I" rather than going at the end of the sentence referring to how he could stop the heart from crying.
“というの” I did research on this one since it did confuse me quite a tad, I found that it's most commonly used as "someone says A" or "I heard that A". The translations I've found the most are "means", "that is to say", or "because"; since he is referring to himself I figure the の gives it a somewhat possessive tone, though if it doesn't I still believe it would be "because" in the end due to the 誰 at the beginning.
“叫んだ” I've found could be a colloquial inflection of “さけんぶ” where as the だ replaces ぶ, it's still a particle meaning "is".
Now “声を” being at the end kind of confuses me a little, as the を is indeed referring to the subject at hand, why is at the end and not before sakenda, or even before kokoro? Does the placement have a specific effect or is that just more grammatically correct?
I know this is a lot to go through for just a simple sentence, but I truly want to learn at least this much so in the future I'm better equipped for sentences like this. Be as thorough as you can if possible, also let me know of any questions you may have, sometimes I don't explain stuff in the best possible manner.
Thank you for your time.