Between the physical world of vibration, as measured by apparatus, and the world of consciously heard music there is a third area of investigation. Our auditory apparatus and/or mind separates different instruments and tones, hears some vibrations but not others, adds tones to fill out the sound spectrum, etc. This middle ground is the province of the psychology of music, a subject about which even many physical scientists know little.

This introduction, by the developer of the Seashore test ...