Once upon a time, when he was only 16 years old, Mick Jagger bit off the top of his tongue. There seem to be some confusion whether it was during a basketball game, a soccer game, or during a gymnastics event, but regardless, when he was 16 he bit off the tip of his tongue, or so his publicists say. Mick couldn’t really speak well for that first week but when he did, people noticed that he had lost his “posh London accent” and had started speaking in a Cockney-like slang- a dialect where his voice was more gravelly and bluesy sounding.
In 1962 the Rolling Stones were formed, and being a counter-culture band, the more gravelly/bluesy voice seemed to fit right in.
I am skeptical that he had bit off that much, and even more skeptical that his speech patterns had changed all that much, but it does make for a good story. There is a growing body of research on people who intentionally have their tongues altered surgically to get a forked tongue. This dramatic cutting appears to have no effect on their speech patterns or gravel sound to their voice.
But back to music…. Whether it’s vocals, strings, brass, woodwind, or percussion, music is make up of a vibrating source and a resonant chamber or amplified device. In the case of speech, the vocal chords vibrate at anywhere from about 100 times a second for very large truck drivers, to over 400 times a second or Hz for small children. Women’s vocal chord vibration is on the order of 200-300 Hz, and a man’s below that. My vocal chords vibrate at 125 Hz in their natural state.
The change in vocal chord state results in certain sound qualities such as a “gravelly” voice, a “breathy” voice, or a “husky” voice. That is, changes in voice sound qualities are the result of changes in the mechanics of the vocal chords and have little to do with the articulation of the tip of the tongue against the roof of the mouth, or against the teeth.
The accident that Mick Jagger had could have altered his accent (perhaps by avoiding where the tongue ultimately articulated) but there is nothing in speech sciences that tongue damage would have created a more gravelly or bluesy voice.
In the case of stringed instruments it’s usually a bow, a finger, or a plastic pick; and each of these differing “source-of-vibration” methods would create a different sound. Different reeds, mouthpieces, or embouchure patterns for woodwind instruments would again change the quality of the sound, but both reeds and strings are comparable to a singer’s vocal chords, and not their tongue.
In any event, for Mick Jagger to have a more gravelly or bluesy voice after the tongue biting accident, he would have to have encountered some other accident that damaged his vocal chords. Perhaps when he swallowed the tip of his tongue, it caused nodules or some other abrasive pathology on one or both vocal chords? Who knows- he may have sounded like Rod Stewart?