So I began researching some examples:
Firstly, in Pixar's Film Ratatouille, this technique is used when Remy visualises the tastes he is experiencing when eating food.
It shows how taste is added to music and then representation in an abstract way.
In Disney's Fantasia, once again music notes are visualised into abstract shapes. In this case, the music assumes a visual shape, a character, therefore it interacts better with the audience.
Finally, while researching this technique I found a quite interesting short animation Danse Macabre by Brian Allen Carol done as a tribute to German animator Oskar Fischinger. In this case, the music is once again shown in a representative way, emphasising the notes played by the music as well as the feelings evoked by it.
Now it is time to get back to the animatic, finish it and then find a way to visually interpret the music heard.