Nope, the period doesn't affect the sentence. Today, the answer is accepted also.
I feel ashamed: I know голос because of the show The Voice in Russia... I wish they were quiet, can't stand the show! :D
what about silent voice? is there any reason why "silent voice" is not correct?
I usually use the word silent to describe something absolutely quiet, so not a voice that by definition you can hear. Other people might disagree, but either way it's just not the same word.