Speech intelligibility is the standard criterion for hearing function

Evidence

Most importantly, a hearing impairment can affect orientation in the environment and communication based on sound. Hearing of speech is a fundamental ability for humans, and therefore speech intelligibility has often been used as the basic criterion of the functionality of hearing. However, even a mild hearing impairment affects the perception of details in sound, for example nuances in music. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 2627

Categorization

• DEFINE: Defines the field’s primary functional metric: speech intelligibility as the criterion for hearing functionality, with music nuance as a secondary casualty of mild loss.