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7 The Amazing Diversity of Brass Instruments
Although instrument makers often provide a mouthpiece when they supply an
instrument, players most usually make a separate choice. Interchangeability of
mouthpieces is generally catered for by makers: the tapers of instrument mouthpiece
receivers and of mouthpiece stems are not completely standardised but do, for most
instruments, allow players to choose from a considerable range of mouthpieces.
The bore in the instrument just beyond the end of the mouthpiece stem is itself
acoustically significant, so each kind of instrument tends to have mouthpieces with
a narrow range of stem diameters. There are exceptions, such as the rare models of
trumpet which are designed to take cornet mouthpieces.
Mouthpieces cannot be specified adequately by a small number of parameters.
The parameter most often cited is the cup diameter, because of its great influence
on the embouchure and the feel to the player. A relatively wide cup is generally
considered to facilitate ‘lipping’ wayward notes into tune on the natural trumpet.
Cup diameters vary from 12 mm or less in cornettino mouthpieces to 30 mm or more
in the largest tuba mouthpieces, the limits dictated by the size of the human lip rather
than by the nature of the instrument. The edge between the rim (placed against the
lips) and the cup is known as the ‘bite’ of the mouthpiece, and its curvature is also
important for a comfortable and flexible embouchure.
The aerodynamic and acoustical functions of a mouthpiece may be usefully
characterised by cup volume and cup shape, parameters which might have a
greater effect on timbre and response and are not constrained in any way by
the size of the human lip. Working definitions of cup volume and cup shape
are given in Sect. 7.7. Similar mouthpieces are in some cases frequently used for
quite different instruments. For example, mouthpieces for baritone saxhorn and
for tenor trombone are almost completely overlapping categories. Similarly, no
distinction can consistently be made between mouthpieces for bass trombone and
for euphonium.
In Sect. 4.3.6 we discussed the effect of the mouthpiece cup on the resonances
of a system consisting of a tube with inserted mouthpiece. The amplitudes of the
input impedance peaks with frequencies in the region of the resonance frequency
of the detached mouthpiece are boosted. The mouthpiece cup volume has a strong
effect on the response of a brass instrument as a whole, as players will confirm. The
boost given to the resonances of the instrument plus mouthpiece system needs to
be in the region of the impedance peaks employed in the normal playing tessitura
of the instrument. A simple experiment is to attempt to play a tuba with a trumpet
mouthpiece or vice-versa: in either case notes can be sounded, but it is impossible to
produce a musically acceptable sound in the normal playing range of the instrument.
To characterise a mouthpiece we need to establish one or more parameters which
reflect the contribution of the cup volume. In Sect. 4.3.5 we discussed the ‘popping
frequency’ of a detached mouthpiece. This is clearly related to the cup volume,
and also to the throat cross-sectional area, but popping frequency also depends on
the length and shape of the backbore of the mouthpiece. When the mouthpiece is
inserted into an instrument the backbore becomes part of the overall bore profile
of the instrument, and the point where the mouthpiece ends and the inside the
7 The Amazing Diversity of Brass Instruments
Although instrument makers often provide a mouthpiece when they supply an
instrument, players most usually make a separate choice. Interchangeability of
mouthpieces is generally catered for by makers: the tapers of instrument mouthpiece
receivers and of mouthpiece stems are not completely standardised but do, for most
instruments, allow players to choose from a considerable range of mouthpieces.
The bore in the instrument just beyond the end of the mouthpiece stem is itself
acoustically significant, so each kind of instrument tends to have mouthpieces with
a narrow range of stem diameters. There are exceptions, such as the rare models of
trumpet which are designed to take cornet mouthpieces.
Mouthpieces cannot be specified adequately by a small number of parameters.
The parameter most often cited is the cup diameter, because of its great influence
on the embouchure and the feel to the player. A relatively wide cup is generally
considered to facilitate ‘lipping’ wayward notes into tune on the natural trumpet.
Cup diameters vary from 12 mm or less in cornettino mouthpieces to 30 mm or more
in the largest tuba mouthpieces, the limits dictated by the size of the human lip rather
than by the nature of the instrument. The edge between the rim (placed against the
lips) and the cup is known as the ‘bite’ of the mouthpiece, and its curvature is also
important for a comfortable and flexible embouchure.
The aerodynamic and acoustical functions of a mouthpiece may be usefully
characterised by cup volume and cup shape, parameters which might have a
greater effect on timbre and response and are not constrained in any way by
the size of the human lip. Working definitions of cup volume and cup shape
are given in Sect. 7.7. Similar mouthpieces are in some cases frequently used for
quite different instruments. For example, mouthpieces for baritone saxhorn and
for tenor trombone are almost completely overlapping categories. Similarly, no
distinction can consistently be made between mouthpieces for bass trombone and
for euphonium.
In Sect. 4.3.6 we discussed the effect of the mouthpiece cup on the resonances
of a system consisting of a tube with inserted mouthpiece. The amplitudes of the
input impedance peaks with frequencies in the region of the resonance frequency
of the detached mouthpiece are boosted. The mouthpiece cup volume has a strong
effect on the response of a brass instrument as a whole, as players will confirm. The
boost given to the resonances of the instrument plus mouthpiece system needs to
be in the region of the impedance peaks employed in the normal playing tessitura
of the instrument. A simple experiment is to attempt to play a tuba with a trumpet
mouthpiece or vice-versa: in either case notes can be sounded, but it is impossible to
produce a musically acceptable sound in the normal playing range of the instrument.
To characterise a mouthpiece we need to establish one or more parameters which
reflect the contribution of the cup volume. In Sect. 4.3.5 we discussed the ‘popping
frequency’ of a detached mouthpiece. This is clearly related to the cup volume,
and also to the throat cross-sectional area, but popping frequency also depends on
the length and shape of the backbore of the mouthpiece. When the mouthpiece is
inserted into an instrument the backbore becomes part of the overall bore profile
of the instrument, and the point where the mouthpiece ends and the inside the