subtonic

Adjective

 * 1)  Of or pertaining to imperfectly articulated sounds or utterances that are inaudible or barely audible, as characterized by Dr. James Rush (Guide to Pronunciation, 1833).

Noun

 * 1)  The note immediately below the upper note of a musical scale.
 * 2)  An imperfectly articulated sound or utterance, as characterized by Dr. James Rush (Guide to Pronunciation, 1833).