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THOMAS GOLD - AHEAD OF HIS
TIME
If the term 'ahead of their
time' applied to anyone in auditory
research - it applied to Thomas Gold
who died in June this year (2004) aged
84. Gold is widely celebrated as a
cosmologist, geophysicist and original
thinker with major contributions to
theories of the origin of the universe,
the nature of pulsars, the physics of
the magnetosphere, the extra
terrestrial origins of life on earth -
and much more. But for just a few years
between 1945 and 1950 Gold was deeply
engaged in state-of-the-art auditory
research at the Physiology Department
of Cambridge University England. There
he recorded the fine frequency tuning
of primary auditory neurones and
conducted penetrating psychoacoustic
experiments on human frequency
discrimination. He boldly challenged
Bekesy's interpretation of cochlear
mechanics, he was the first to propose
an 'active' cochlear process involving
electro-motile elements to enhance the
cochlea's response to sound vibration,
and the first to predict and search for
spontaneous otoacoustic
emissions1.
From theoretical and experimental
considerations Gold was convinced that
the majority of auditory frequency
analysis had to be undertaken
mechanically in the cochlea before
transduction and he believed that this
tuning had to be sharp. Unlike
Helmholtz a century before, Gold was
well equipped to calculate the
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effect physical damping would have on vibrations in
the cochlea and he recognised the impossibility of
achieving fine frequency tuning in the cochlea -
given its structure and the physical properties of
tissue and cochlear fluids. The dilemma really
troubled him. At the 'Cochlear Mechanics' meeting
in Keele 19882 Gold recalled how, in the
late 1940s, he went to visit von Bekesy to explain
to him that the large scale models Bekesy was
working on grossly underestimated the damping in
the cochlea and that the unaided cochlea could
never account for auditory frequency selectivity.
He had hoped Bekesy would guide him towards a
mechanism but Gold returned disappointed,
frustrated and even more determined to find the
answer.
The radical solution he came up with - that of
electro-motility (actually piezo-electric action)
and positive feedback1- drew on his deep
theoretical understanding of physics, of signal
processing, of electronic systems using feedback,
and on his confidence in nature to solve problems
too complex for our technology. In an interview
recorded for the ARO midwinter meeting 2003 Gold
recalled "Suddenly it dawned on me … the
body would have invented positive feedback and a
control system. It just came to me in a flash that
nature is always so clever that if there is a way
out of that dilemma [damping versus tuning]
then that's what it's got to be."3
Gold's startling concept was largely ignored but
seriously considered by a few - including Hallowell
Davis. It was quickly rejected on the grounds that
positive feedback and sharp mechanical tuning would
inevitable bring instability and audible ringing to
normal hearing - contrary to experience. Gold
tried to explain that such phenomenon would be
confined to certain abnormal ears. But he tried
and failed to record objective tonal tinnitus to
support his hypothesis. Funding for this work
dwindled and he left auditory research for a very
distinguished career in other fields.
Usually, when we mourn the passing of a great
auditory researcher we can point to a large
tangible legacy of papers and discoveries. Gold is
different. We are left wonder how different
peripheral auditory research might have been if
Gold had remained in the field… if his radical
thinking had been understood and accepted by the
leading auditory researchers of the day… if in
1948 he had succeeded in proving his hypothesis.
But the truth is that Gold was just too far ahead
of his time- conceptually, theoretically and
technologically. Throughout is subsequent cosmic
exploits Gold kept one ear to the ground - anxious
to hear if and when his ideas on hearing had been
proved right. And they were. During the 1980s he
derived great satisfaction from learning about the
demonstration of hair cell motility and of sharp
basilar membrane tuning, and from Hallowell Davis's
eventual 'conversion' to the active cochlea
hypothesis. He was proud of his active ear proposal
and wanted his contribution to be more widely
acknowledged. Interestingly he never really
embraced the concept of stimulated acoustic
emissions as these implied some imperfection in the
system nature had developed!
Where do such quantum leaps come from? In
answer to that question Gold replied ''I'm a
compulsive thinker, I never turn my brain off, I've
never in my life complained of being bored because
Im constantly thinking about some problem, mostly
physics I suppose. A problem is always on my mind
- evidently even in my sleep because I often wake
up with a solution clearly spread out."3
In 1948 Gold dreamed of an active cochlea. It
took auditory science 40 years to catch up with
him.
David T Kemp July 2004
1 Gold T (1948) Hearing II. The physical basis of
the action of the cochlea. Proc. Roy. Soc. B, 135,
492-498
2 Historical background to the proposal 40 years
ago of an active model for cochlear frequency
analysis" T. Gold 1989 in Cochlear Mechanisms -
structure function and models Eds J.P.Wilson,
D.T.Kemp Plenum Press, New York pp299-305
3 Recorded Interview with T Gold February 2003 to
be published by D.T.Kemp.
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