Pedal tone
From Wikipedia, the free encyclopedia
- For "pedal tones" in the orchestrational sense, see pedal point.
Pedal tones are special notes in the harmonic series of cylindrical-bore brass instruments. A pedal tone has the pitch of its harmonic series's fundamental tone. It is specially named, however, because the physics of cylindrical brass do not provide a natural mode of vibration at the fundamental frequency.
A closed cylinder has modes of vibration at only the odd partials in its harmonic series. This set of pitches is too sparse to be musically useful for brass instruments; therefore, the bells and mouthpieces of brasses are crafted to adjust these pitches. The bell significantly raises all pitches in the series, and the mouthpiece limits the amount to which higher harmonics are raised. The resulting set of pitches is a new harmonic series altogether, one with every member (except one) present instead of only the odd members.
The member not present in the new series is the fundamental. The original fundamental is not raised all the way to the new fundamental pitch, and the original third harmonic becomes the new second harmonic.
The new fundamental can be played, however, as a pedal tone. The higher resonances of the new series help the lips vibrate at the fundamental frequency and allow the pitch to sound. The resulting tone relies heavily on overtones for its perception, but in the hands of a skilled player, pedal tones can be controlled and can sound characteristic to the instrument.
Pedal tones are called for occasionally in advanced brass literature, particularly in that of the trombone.hu:Pedálhang
