Evaluating on Movie "M" for sound

I could tell this movie was gonna have a lot of old technology problems like hiss, clips and stuff when I began the movie at black and white graphics, also estimating the time of movie it was released about 3/4 th of a century ago. However I didn't get that disappointed by the end of the movie. A good movie is the one that expresses its self being alive without any thing making its viewers out of its magic in my point of view. For this movie "M" It was about the same to be a good movie except I felt out of the story every time there is a distracting sound that seems to not fit in the place, or the sense of lack of sound or in other term , the editing had a lot of flaws in that sense but It was made a lot years ago and still made it to entertain for the viewer like me in this 21st century. That could be made a remark that how sound could influence to make a great movie.
M has a good sense of sound put together to make it a good movie even with its flaws of feeling of unreality.