Percussion instrument played to produce sounds of indeterminate pitch
An unpitched percussion instrument is a
percussion instrument played in such a way as to produce sounds of
indeterminate pitch, or an instrument normally played in this fashion.
Unpitched percussion is typically used to maintain a
rhythm or to provide
accents, and its sounds are unrelated to the
melody and
harmony of the music. Within the
orchestra, unpitched percussion is termed
auxiliary percussion, and this subsection of the
percussion section includes all unpitched instruments of the orchestra however they are played, for example the
pea whistle and
siren.
A common and typical example of an unpitched instrument is the
snare drum, which is perceived as unpitched for three reasons:
The snares produce sounds similar to
white noise, masking definite frequencies.
The strongest frequencies that are present are unrelated to pitched sounds produced by other instruments in the
ensemble. Although the drum is tuned by the player, this tuning does not relate to the pitches of other instruments.
The snare drum illustrates the three main ways in which a sound can be perceived as indeterminate in
pitch:
The sound may lack any
fundamental frequency sufficiently loud to produce a sensation of pitch, for example a sound consisting of
noise, or a mixture of sounds containing a great deal of such noise.
The sound may be inharmonic, a mixture of sounds including some with conflicting fundamental frequencies. The sound of a freely resonating
membrane such as a drum head, for example, contains strong
overtones at
irrational ratios to its fundamental, unlike a
vibrating string whose overtones are at simple whole-number ratios to the fundamental.[1]
The fundamental frequency may simply be unexpected, and unrelated to other sounds in the piece of music. A heavy rock drummer playing on the
bell of a
ride cymbal, for example, produces a sound with a strong fundamental, but the pitch is unrelated to the music. This is unpitched percussion, despite the recognisable pitch of the sound if heard in isolation.
In practice, two or all of these mechanisms are frequently in effect in producing the sensation of an instrument being unpitched, but any one can be sufficient.
Many unpitched percussion instruments do, or can, produce a sound with a recognisable fundamental frequency, and so can also be used as
pitched percussion. The pitch of a
bell is particularly strong however struck. The sound of a
floor tom played with normal
drumsticks is inharmonic, but the same drum played with the mallets and in the fashion of a
timpani can produce a recognisable pitch, without requiring any retuning.
More radically, pitched instruments can be used to produce unpitched sounds, for example a
prepared piano, or the
golpe technique of
flamenco music.
Within a set of unpitched percussion instruments, there is commonly a sense of higher and lower pitch, for example:
The smaller of a set of two
timbales or
bongo drums is tuned higher than the larger.
The smaller
tom-tom drums in a
drum kit are tuned higher than the larger ones. Three or more tom-toms are common, each tuned higher than the larger ones and lower than the smaller ones.
The male pair in a set of
castanets is lower in pitch than the female.
These pitches however:
Relate only to other members of the set, or to related unpitched instruments (for example the bass drum to the tom-toms in a drum kit), rather than to the pitched instruments in the ensemble.
These harmonic relationships may or may not be understood by the players themselves, but are consistently produced by skilled performers within the tradition,[citation needed] and this skill in tuning is passed on to their students. Failure to recognise these relationships is a common cause for such instruments sounding bad in the hands of beginners and players from other traditions, when heard by those familiar with the tradition.
Instruments used in both roles
Instruments regularly used both as pitched and as unpitched percussion include many types of
bells.
Lincoln Cathedral, for example, has three bell towers, two containing bells used as unpitched including a
chiming clock, and the third containing a pitched
ring of bells.
Untuned percussion
Traditionally, unpitched percussion instruments are referred to as untuned percussion, and this remains a common concept and term, and a common name for the
auxiliary percussion subsection of the
percussion section of the
orchestra. However, the terms tuned percussion and untuned percussion are avoided in recent
organology, for two main reasons:
Many untuned percussion instruments are tuned by the player, for example the
snare drum, but this tuning does not relate to producing a perceived pitch.
Many percussion instruments are used in both pitched and unpitched roles in different styles or pieces of music, for example the
cowbell, and during the 20th century there was much experimentation in using instruments normally used in one role or the other for the opposite role, further blurring the distinction between the two types. The term unpitched refers to the usage and perception of the sound of the instrument rather than simply to its sound, which is the more recent approach.