I was recently asked this question via e-mail:

Dear Mick: First, I love your voice! I am wondering how you can be so versatile, singing deep baritone things like Pearl Jam one minute, then singing really high things like Heart and AC/DC the next.
~Lisa S.

Lisa:

The answer to your question lies in two parts. First, I drink a great deal of Captain Morgan on a daily basis. I find that Morgan relaxes my vocal chords to the point where I don’t strain them beyond a level that I can easily recover from.

Second, after years of personal research, I have developed the Klein Nutsack Squeezer™ (KNS). The Nutsack Squeezer is a remote controlled device worn in the underwear. It attaches to the scrotum via a complex series of cables and trusses. The picture at top left shows me singing a sort-of-regular-kind-of-Pearl Jam-type-thing, not too high, not to low. A comfortable range to sing in.

Since I am in a band with two bastards who insist on playing things by Rush and Heart and Dream Theater, I often find myself needing to sing way up high on a moments notice. The next picture shows me hitting such a note. I do this by activating the KNS™ via a remote control which is attached to one of the tuning keys on my bass.

The diagram at bottom left shows the KNS™ in action. A flick of a switch, a momentary discomfort in the nether regions, and I am singing 3 octaves above my normal range.