54
Henry C. Bennet-Clark
first observation showed that the loading of the tympanum due to MUller's organ
acted as viscous damping on the membrane, so mechanical power was being
absorbed from the membrane by the sensory cell regions of MUller's organ. The
second observation showed that approximately half the energy of vibration of the
system was being transferred from the tympanum (as the source) to MUller's organ
(as the load) suggesting that the system closely meets the requirements of the
maximum power transfer theorem (Sect. 2.2).
A
Structures on the locust tympanum
Anterior
cells
membrane
Muller's
organ
B
Calculated resonant frequencies
Dorsal
Ventral
Fig. 5 A, B. Diagram of the right ear of a locust viewed from the inside. A shows the
sclerites in the tympanum and the attachments to them of the different groups of sensory
cells. B shows the resonant frequencies that were calculated for the differently crosshatched regions of the tympanum and for MUller's organ (all groups of sensory cell s)
based on measurements of the compliance of the different structures and their estimated
masses. The stippled thick membrane and the arc of thin cuticle around the posterior part ot
the tympanum (left in hatched) appear to delimit the vibration of the tympanum. (After data
in Stephen and Bennet-Clark 1982)
4.5 How Effective is Impedance Matching in Auditory Systems ?
Throughout Section 4, I have endeavoured to show that some form of impedance
matching occurs between the different steps in the auditory chain. However, few
systems have been studied consistently and so hard numbers are difficult to obtain.
Even so, the picture that emerges is that stage-to-stage impedance matching occurs
in auditory systems as well as in sound-producing systems. As a consequence, ears
Henry C. Bennet-Clark
first observation showed that the loading of the tympanum due to MUller's organ
acted as viscous damping on the membrane, so mechanical power was being
absorbed from the membrane by the sensory cell regions of MUller's organ. The
second observation showed that approximately half the energy of vibration of the
system was being transferred from the tympanum (as the source) to MUller's organ
(as the load) suggesting that the system closely meets the requirements of the
maximum power transfer theorem (Sect. 2.2).
A
Structures on the locust tympanum
Anterior
cells
membrane
Muller's
organ
B
Calculated resonant frequencies
Dorsal
Ventral
Fig. 5 A, B. Diagram of the right ear of a locust viewed from the inside. A shows the
sclerites in the tympanum and the attachments to them of the different groups of sensory
cells. B shows the resonant frequencies that were calculated for the differently crosshatched regions of the tympanum and for MUller's organ (all groups of sensory cell s)
based on measurements of the compliance of the different structures and their estimated
masses. The stippled thick membrane and the arc of thin cuticle around the posterior part ot
the tympanum (left in hatched) appear to delimit the vibration of the tympanum. (After data
in Stephen and Bennet-Clark 1982)
4.5 How Effective is Impedance Matching in Auditory Systems ?
Throughout Section 4, I have endeavoured to show that some form of impedance
matching occurs between the different steps in the auditory chain. However, few
systems have been studied consistently and so hard numbers are difficult to obtain.
Even so, the picture that emerges is that stage-to-stage impedance matching occurs
in auditory systems as well as in sound-producing systems. As a consequence, ears