160
4 After the Lips: Acoustic Resonances and Radiation
Fig. 4.51 (a) A single tonehole of radius b in an infinitely long cylinder of radius a. (b) Part of a
lattice of toneholes with identical hole dimensions and equal inter-hole spacing s
Fig. 4.52 (a) Tonehole on a
serpent. (b) Tonehole on an
ophicleide, with chimney, key
and pad
The effective acoustic length of the side branch is l e h + 1.6b; the second
term on the right-hand side of this equation includes effects of the inertia of the
air in the branch and the radiation of sound from the open end. When a sinusoidal
sound wave travelling along the main tube arrives at the open tonehole, some of the
energy is transmitted down the main branch, some is radiated from the tonehole,
and the remainder is reflected back up the main tube. The sound power transmission
coefficient T m is the fraction of the sound power which is transmitted past the
tonehole (Kinsler et al. 1999). For a tonehole of radius b and effective length l e
on an infinite cylinder of radius a,
4 After the Lips: Acoustic Resonances and Radiation
Fig. 4.51 (a) A single tonehole of radius b in an infinitely long cylinder of radius a. (b) Part of a
lattice of toneholes with identical hole dimensions and equal inter-hole spacing s
Fig. 4.52 (a) Tonehole on a
serpent. (b) Tonehole on an
ophicleide, with chimney, key
and pad
The effective acoustic length of the side branch is l e h + 1.6b; the second
term on the right-hand side of this equation includes effects of the inertia of the
air in the branch and the radiation of sound from the open end. When a sinusoidal
sound wave travelling along the main tube arrives at the open tonehole, some of the
energy is transmitted down the main branch, some is radiated from the tonehole,
and the remainder is reflected back up the main tube. The sound power transmission
coefficient T m is the fraction of the sound power which is transmitted past the
tonehole (Kinsler et al. 1999). For a tonehole of radius b and effective length l e
on an infinite cylinder of radius a,