(n) illusory auditory perception of strange nonverbal sounds

noun. An unspoken hallucination, like a humming in the ear, calling out, or ringing noise.

Rarely used term for an auditory hallucination in which indefinite sounds, such as ringing or hissing, are heard. Synonyms: acouasm. Origin: G. Akousma, something heard (05 Mar 2000)

What is heard, from the Greek word acouo...hear, listen.
The acousma of classical music.
Acoustic guitar......