Which skill must a performer, composer and listener all possess.
A performer, composer, and listener all must possess the skill of active listening. Active listening is the ability to understand and appreciatively engage with music. Although the skills needed by a performer, composer, and listener vary significantly in other areas, active listening is a common thread connecting all three roles.
For a performer, active listening helps with interpretation, matching pitch and timbre with others (in ensembles), maintaining rhythm and tempo, and responding dynamically to other musicians and the conductor.
For a composer, active listening is crucial for understanding the musical language, learning from existing works, imagining new musical ideas, and ensuring that the composed music will effectively communicate the intended emotional or conceptual message.
For a listener, active listening enhances the ability to appreciate finer nuances, understand the structure and elements of music, recognize themes and variations, and gain a deeper emotional connection to the piece.
Moreover, all three should have a good understanding of the basic elements of music (such as rhythm, melody, harmony, form, and texture) as well as a degree of musicality. However, the depth and application of these skills will vary according to their different roles in the musical experience.