The use of ambient sound and visuals to convey a sense of loneliness and isolation without music is an effective artistic choice that can strongly influence the film's atmosphere. Here are some ways this can be achieved:
Consciously avoiding music allows for silence, which can be powerful in itself. The absence of background music accentuates the emptiness and silence in the environment. Ambient sounds, such as the wind rustling through trees, footsteps on a deserted path, or other natural sounds, can enhance the sense of loneliness.
The simple story with one character enhances the feeling of loneliness. The audience can focus more on the emptiness and isolation of the character without distractions from other plotlines.
The strength of a film without music lies in focusing on the essence of visuals and ambient sounds. It allows the viewer to delve deeper and connect with the loneliness of the character. However, it requires careful planning and execution to ensure that the message is clear.