M (1931) is a German thriller that was created just after the technological union of sound and film. Thus, as a sound film, M had room for opportunity and innovation movies before it did not have. The sound in this film plays an important role in that it not only makes things more realistic, it makes the interaction within more human and palpable for the audience. In addition, important consequences arise from the presence of sound in the narrative. The drama and emotion conveyed are heightened in comparison to silent films which largely relied on exaggerated facial expressions to express emotions and title cards to continue forward the narrative.
A prime example of this new use of sound in M is within the editing and use of a voice overlay called a sound bridge. There is a shot showing people in the streets crowding around the news bulletin of the recently discovered murder of a child. Paranoia was clearly ever increasing. One man in the crowd said "you in front, read it out loud!" from which a voice began to read the flyer. A voice which one would assume to be that of a person in the crowd. The voice stops and someone even yells "Louder, we can't hear a word" something which further implies the voice emanates from a man within the crowd. The shot stays on the crowd while the voice begins reading and then suddenly switches over to a shot of several men smoking and drinking at a table with one of them reading the same news from the paper. The voice was that of the man sitting at the table throughout. This is certainly an innovative use of sound and editing. This scene really gives a sense of the large scale paranoia and fear the murderer has induced in every citizen throughout the city while also showing a smaller scale discussion and argument of the matter, relaying to the audience the absolute feeling of contempt everybody feels for the murderer. Therefore, as well as having innovative sound use, this scene serves two very important roles of imparting the feelings of citizens onto the audience in addition to continuing forward the narrative in an efficient manner.
Another interesting facet of this new usable technology in film is one of contrast. Sound is now an additional option, thus the lack of sound (silence in film, which earlier been thoroughly explored) can add intriguing effects. A definitive example of this is the scene where the mother's daughter has gone missing. She yells her daughters name while searching for her, giving a certain sense of helplessness and terror. Then suddenly the shot cuts to the chair where she usually sits to eat now empty, and then shows her ball rolling down a slope, and then her balloon flying away and becoming entangled in power lines. There is not one bit of sound during this set of shots. The silence gives a feeling of something missing, of something being not right. Therefore the lack of sound in this case serves to reinforce the atmosphere and sense of the wrongdoing taking place. Hence, sound serves as an additional dimension with room for contrast and more possibilities.
Furthermore, sound is what leads to the ultimate demise of the antagonist. The recognition of his distinctive whistling song "In the Hall of the Mountain King" (the first use of leitmotif in a movie which is used to indicate the presence of the character) by the blind balloon salesman really plays to the fact that sound adds an additional layer to both the film and the narrative.
The ending of the film is quite perplexing aspect and leaves room for imagination. It ends rather abruptly does not give a sense of closure. It almost seems in a way a forceful attempt to add a moral or message into the movie. The apparent sorrow of the victims' mothers and their words of self-guilt serves to fuel the disdain the audience has for the murderer even further. A verdict is not given which causes one to wonder what degree of justice has been served (given the relatively inept police force) in relation to the thieves "kangaroo court".