suggesting that the frequency component of a sound
is transmitted to the brain encoded as the rate of nerve fibre firing.
As with the previous proposal, Rutherford's theory could not account for
the perception of sound through the whole of the auditory range but only
for low frequency sounds. The travelling wave theory of Bekesy, ( 1960),
is a modification of Helmholtz's theory. It proposes that the displacement
of the BM produces eddy currents in the endolymphatic fluid and that these
serve to concentrate pressure on particular hair cells thus providing a
narrowing of the stimulus area. Wever, (1949) in turn modified Rutherford's
theory to extend its range of pitch perception in the so called volley
theory. He suggested that nerve fibres fire in synchronism, so that several
fibres are associated with one pitch. Even this, however, could not account
for frequencies above lOOOHz. Whitfield's, (1967) boundary theory is another
alternative which attributes pitch perception based upon pattern recognition
by the auditory system of the pattern of fibres. He states that:
"Each frequency gives rise to a unique configuration, since both the
extent of the activity and the position of the amplitude maximum change
with frequency. Each pattern contains, therefore, the necessary data to
define the frequency and intensity."
Current opinion is that the perception of pitch cannot be accounted
for in any single theory but rather it would appear to require the attributes
of several.