Palm mute
Guitar technique in which the strings are damped with the heel of the picking hand.
What it means
Palm muting is a guitar technique in which the heel of the picking hand is laid lightly on the strings near the bridge. The strings then vibrate only briefly and the note sounds damped and dull, but with a clear attack. The degree of damping depends on the pressure of the hand.
In the notation
In scores and tablature the technique is shown with P.M. and a dashed line above the notes concerned. The end of the line shows when the player returns to open picking.
Musical use
Palm muting is a central feature of rock, metal, punk and funk. In fast quavers on the low strings it creates the typical "chugging" riff sound. In acoustic music the technique is also used for accompaniment, then with less pressure.
Palm muting should be distinguished from muting with the fretting hand, in which the strings are stopped with the fingers of the left hand, and from staccato, which shortens the duration in general without a particular sound effect.
Performance practice
Lay the heel of your hand loosely where the string and bridge meet. Vary pressure and position until you find the sound you want: too little pressure lets the string ring, too much chokes the tone. Pick evenly with the plectrum.