> I am glad you brought this up again Peter,
>
> I have no problem with the passive travelling wave, however
> with respect
> to actively induced movements, the latest experimental data
> shows that
> there are ONLY forward travelling waves (check Ren's
> experiments for
> example).
>
> OAEs are generated locally (this is common belief)
> consequently one
> assumes that the basilar membrane is not on the surface, but
> suspended
> inside the pond and the oval/round windows are on the surface
> of the
> pond.
>
> What's more, if the OHCs in the apex are regarded as deep
> ocean
> movements, then the waves resemble tsunamis ! Consequently
> only
> movements near to the shore/surface (the windows) are easily
> observable
> - the not easily observable being the small movements of the
> OHCs in the
> apex themselves and the pressure waves (large in potential but
> tiny in
> flux or velocity) in the incompressible fluid.
>
> Matt
>
>
> On Wed, 2011-09-21 at 12:21 +0200, Peter van Hengel wrote:
> > Dear dr Heerens and list-members,
> >
> > I hesitate to get involved in this discussion as I have
> tried to
> > explain the hydrodynamics behind (transmission line) cochlea
> models
> > before in another thread on this list and don't like
> repeating myself.
> > But I feel I have to lend my support the comments made by
> Dick Lyon.
> > As I have stated before fluid physics states that a fluid
> domain (such
> > as the cochlea or a pond) with a flexible boundary subject
> to a
> > restoring force (such as the aochlear partition or the pond
> surface)
> > MUST exhibit 'ripples' on the surface. In the cochlea these
> are
> > refered to as traveling waves. The wave energy is not
> traveling in the
> > boundary itself but in the fluid. Any attempts to prove that
> such
> > waves do not exist, or are based on 'bad physics', are
> unfortunately
> > based on a lack of understanding of the fluid mechanics.
> > Whether the traveling wave is the only mechanism responsible
> for
> > transporting sound energy to the hair cells is still a valid
> question,
> > but untill an alternative model produces similar or better
> results on
> > modeling physiological, pshychophysical and OAE date, I'll
> stick with
> > the transmission line. Things like pitch perception and the
> missing
> > fundamental can perhaps not be explained purely by looking
> at the
> > average excitation caused by the traveling wave, but I don't
> think
> > anyone ever claimed they could. In my opinion it is good to
> develop
> > new theories, but we should attempt to integrate them with
> existing
> > ones instead of throwing away something that has proven to
> work.
> >
> > Kind regards,
> > Peter van Hengel
> >
> >
>
> > 2011/9/19 Willem Christiaan Heerens <
heerens1@xxxxxxxxx>
>
>
> > Dear Dick Lyon,
> >
> >
> > Thank you for your substantial list of comments. Of
> course I
> > will reply.
> > With pleasure.
> >
> > You wrote:
> > **Sometimes it's hard to get a reaction when you are
> trying to
> > replace a
> > paradigm, as the silence here illustrates. I didn't
> really
> > get into the
> > new ideas of your book much, but I have some
> comments on the
> > introductory
> >
> > material about why you reject the current
> paradigm.**
> >
> > Your reaction in the first sentence is pretty well
> familiar to
> > me. It is
> > entirely in accordance with the procedure described
> by Thomas
> > Kuhn in his
> > world famous 1962 essay:
> >
> > “The Structure of Scientific Revolutions”
> >
> > Besides that: a former colleague of mine, a highly
> skilled
> > senior professor
> > in applied physics, who reviewed our booklet during
> a
> > contribution
> > procedure for a scientific journal, quite recently
> gave us the
> > verdict that
> > he fully agreed with our arguments and statements
> and he urged
> > the editor
> > to make a full scientific discussion possible for
> our views.
> > He also warned
> > me that to be in right is not the same as to be put
> in right.
> > I myself
> > don’t see all this as a problematic issue. It’s part
> of the
> > way messengers
> > or designers of new paradigms are encountered by the
> mayor
> > supporters of
> > the competing one. Of course the scientific
> reputation
> > rankings of so many
> > scientists are involved and in danger in case a
> paradigm shift
> > is
> > happening.
> >
> > The only issue that counts for me is that scientific
> arguments
> > from both
> > sides brought in discussion, verified and weighted
> in a
> > careful way must
> > turn the balance. Ignoring irrefutable arguments
> because they
> > form a thread
> > for the ranking of a scientist has always been
> contra
> > productive for the
> > progress in a field of science. History shows many
> of such
> > examples. One of
> > the most salient among them certainly is the
> Copernican
> > revolution.
> >
> > The result of the second line of your comment I
> really regret,
> > because in
> > the rest of your writings I clearly can see that you
> have
> > apparently
> > missed, misread or misinterpreted a number of issues
> on
> > cardinal points.
> >
> > Let me discuss your next comment:
> >
> > **You discuss and reject two wave concepts: first,
> the
> > pressure sound wave
> > that travels so fast that wavelengths will always be
> long
> > compared to the
> > size of the cochlea, and second, "capillary" or
> "interfacial"
> > waves,
> > presumably meaning those water surface waves where
> gravity
> > provides the
> > restoring force. Of course, neither of these can be
> the
> > explanation for
> >
> > how the cochlea works.**
> >
> > I don’t reject the pressure sound wave concept, at
> least not
> > in general. It
> > is of course the vehicle of mechanical vibration
> energy and
> > therefore also
> > acoustical vibration energy. How could an academic
> physics
> > scientist reject
> > that?
> > What I have argued is that for all the frequencies
> that can be
> > sensed in
> > the cochlea even up to 20 kHz counts that the sound
> velocity
> > in perilymph –
> > being 1500 m/s – in relation with these frequencies
> result in
> > a wave length
> > always larger than 75 mm.
> > So therefore this mechanism cannot contribute to a
> > discriminating mechanism
> > for frequency selectivity based on traveling waves.
> >
> > And regarding the "capillary" or "interfacial"
> waves I
> > reject: yes indeed
> > in quite a number of textbooks I see the comparison
> of the
> > propagation of
> > surface waves in a pond with the slow waves inside
> the
> > cochlea. It simply
> > is an erroneous analogon. None of the parameters
> necessary for
> > the
> > existence of capillary waves can be found inside the
> cochlea.
> > So neither
> > they can play a role in evoking traveling waves that
> have
> > short wavelengths.
> >
> > You wrote:
> >
> > **You also attribute to Lighthill some strange wrong
> ideas
> > about
> > transmission lines only being able to transmit
> energy near
> > their resonance.
> >
> > **
> >
> > Can you be more specific? The only lines I describe
> are the
> > lines in Fig.
> > 1. That figure is a reproduction of the figure in
> Lighthill’s
> > paper:
> >
> > Lighthill MJ. (1981) Energy flow in the cochlea. J
> Fluid Mech
> > 106: 149-213.
> >
> > I haven’t attributed strange wrong ideas to
> Lighthill. I have
> > studied
> > carefully all the 64 pages of his paper.
> >
> > He starts with a very informative series of premises
> and I
> > cite this part:
> >
> > *** With moderate acoustic stimuli, measurements of
> > basilar-membrane
> > vibration (especially, those using a Mössbauer
> source attached
> > to the
> > membrane) demonstrate:
> > (i) a high degree of asymmetry, in that the response
> to a pure
> > tone falls
> > extremely sharply above the characteristic
> frequency, although
> > much more
> > gradually below it;
> > (ii) a substantial phase-lag in that response, and
> one which
> > increases
> > monotonically tip to the characteristic frequency;
> > (iii) a response to a 'click' in the form of a
> delayed
> > 'ringing'
> > oscillation at the characteristic frequency, which
> persists
> > for around 20
> > cycles.
> > This paper uses energy-flow considerations to
> identify which
> > features in a
> > mathe¬matical model of cochlear mechanics are
> necessary if it
> > is to
> > reproduce these experi¬mental findings.
> > The response (iii) demands a travelling-wave model
> which
> > incorporates an
> > only lightly damped resonance. Admittedly, waveguide
> systems
> > including
> > resonance are described in classical applied
> physics. However,
> > a classical
> > waveguide resonance reflects a travelling wave, thus
> > converting it into a
> > standing wave devoid of the substantial phase-lag
> (ii); and
> > produces a low-
> > frequency cut-off instead of the high –frequency
> cut-off (i).
> > By contrast, another general type of travelling-wave
> system
> > with resonance
> > has become known more recently; initially, in a
> quite
> > different context
> > (physics of the atmosphere). This is described as
> > critical-layer resonance,
> > or else (because the reso¬nance absorbs energy)
> > critical-layer absorption.
> > It yields a high-frequency cut-off; but, above all,
> it is
> > characterized by
> > the properties of the energy flow velocity. This
> falls to zero
> > very steeply
> > as the point of resonance is approached; so that
> wave energy
> > flow is
> > retarded drastically, giving any light damping which
> is
> > present an
> > unlimited time in which to dissipate that energy.
> > Existing mathematical models of cochlear mechanics,
> whether
> > using one-, two-
> > or three-dimensional representations of cochlear
> geometry,
> > are analysed
> > from this standpoint. All are found to have been
> successful
> > (if only light
> > damping is incorporated, as (iii) requires) when and
> only when
> > they
> > incorporate critical-layer absorption. This resolves
> the
> > paradox of why
> > certain grossly unrealistic one-dimensional models
> can give a
> > good
> > prediction of cochlear response; it is because they
> > incorporate the one
> > dimensional feature of critical-layer absorption.***
> >
> > Apparently Lighthill has never considered the
> possibility that
> > the observed
> > movements of the basilar membrane could be caused by
> another
> > phenomenon
> > than a sound energy transporting traveling wave.
> >
> > Your next remark:
> >
> > **Actually, he showed the opposite: that a
> sinusoidal wave
> > will propagate
> > until the point where the transmission line
> resonance gets low
> > enough to
> > match the wave frequency, and at that point it will
> slow down
> > to zero
> > velocity and die out. This is not exactly how the
> cochlea
> > works (the BM is
> > not very resonant), but not a bad concept from base
> to near
> > the best
> > place.**
> >
> >
> > You say it clearly enough: ‘It isn’t a bad concept
> from base
> > to near the
> > best place.’
> > So not having an exact agreement between theory and
> practice
> > makes the
> > underlying hypothesis directly vulnerable for
> falsification.
> >
> > Indeed the cochlea cannot react like that. And I
> want to make
> > this clear by
> > the following series of experiments:
> >
> > Entirely based on the premises of the new paradigm I
> have
> > described, I now
> > have calculated a number of predictable sound
> phenomena by
> > using the
> > following frequencies together with prescribed phase
> relations
> > in a
> > standard summation procedure to compose a Fourier
> series:
> >
> > 1:
> > 10000 + 10004 + 10008 + 10012 + 10016 +
> 10020 +
> > 10024 Hz
> > Where all the contributions are sine
> functions.
> >
> > Our paradigm predicts: an undisputable beat of 4 Hz
> in a high
> > beep tone.
> >
> > 2:
> > 10000 + 10004 + 10008 + 10012 + 10016 +
> 10020 +
> > 10024 Hz
> > Where the contributions are successively
> > alternating sine and
> > cosine functions.
> >
> > Our paradigm now predicts: an undisputable beat of
> 8 Hz in
> > the same high
> > beep tone.
> >
> > 3:
> > 10000 + 10004.0625 + 10008 + 10012.0625 +
> 10016 +
> > 10020.0625 +
> > 10024 Hz
> > Where all the contributions are sine
> functions.
> >
> > Our paradigm now predicts: a beep, in which an
> undisputable
> > beat exists
> > that changes every 8 seconds from clearly 4 Hz to 8
> Hz and
> > then reverses
> > again to 4 Hz. So the beat pattern has a period of 8
> seconds
> > caused by the
> > systematic mistuning of 1/16 = 0.0625 Hz.
> >
> > Additional changes in the mistuning, like for
> instance from
> > 10004.0625 into
> > 10003.9375 Hz, of either one, two or three of the
> mistuned
> > frequencies are
> > predicted to give the same results in the beat
> pattern as
> > experiment 3.
> >
> > And actually I want to urge everybody to download
> the software
> > program of
> > Yves Mangelinckx with which these sound complexes
> can be
> > properly
> > calculated in the form of wav files from the
> following site:
> >
> >
>
http://www.a3ccm-apmas-eakoh.be/a3ccm-apmas-eakoh-index.htm
> >
> > [ NOTE: The standard setting in the 1/f mode in
> this
> > software program
> > takes care that all the individually primary
> calculated
> > frequencies
> > contribute equal energy to the resulting sound
> pressure
> > signal. This
> > condition is very important for the influences on
> pitch
> > calculations in
> > case higher values of the differences between
> contributing
> > frequencies
> > exist. ]
> >
> > This in order to give the interested reader the
> opportunity to
> > falsify or –
> > in case our predictions are correct – to verify our
> findings.
> >
> > And of course I wouldn’t have given these examples
> if I wasn’t
> > sure of my
> > statements.
> > I can already inform you that verification will be
> the result.
> >
> > If you carry out the same series of experiments with
> a start
> > frequency of
> > 1000 Hz instead of 10000 Hz, you will hear the same
> series of
> > beat
> > phenomena, but now with the lower beep of the 1012
> Hz instead
> > of the 10012
> > Hz beep.
> > Even if you go down with the start frequency to 200
> Hz or 400
> > Hz you will
> > still hear the same beat phenomena, but now with the
> low
> > humming tone of
> > 200 Hz respectively with the one octave higher
> humming tone of
> > 400 Hz.
> >
> > Hence it is a perception phenomenon that appears all
> over the
> > entire
> > auditory frequency range.
> >
> > And it must be remarked that according to the
> current hearing
> > theory all
> > the used frequencies – especially in the higher
> frequencies
> > like in the
> > 10000 Hz experiments – according to auditory
> experts, and also
> > supported by
> > Lighthill, will propagate by means of a traveling
> wave to one
> > and the same
> > location on the basilar membrane.
> >
> > If we then still follow the current hearing
> paradigm, we have
> > to believe
> > that the medley of that seven totally unresolved
> frequencies
> > will be
> > transferred via one and the same nerve fiber to a
> location in
> > the auditory
> > cortex, where finally out of this ‘Gordian knot of
> stimuli’ a
> > beep with the
> > described and also heard beat patterns will be
> reconstructed.
> >
> > Once these beat phenomena are verified as really
> existing for
> > every
> > listener with a reasonable normal hearing, do you
> agree with
> > me that for
> > the current paradigm this is a very serious anomaly?
> > In my opinion forcing an explanation within the
> framework of
> > the current
> > paradigm will result in such a complexity that the
> general
> > rule in science,
> > known as ‘Ockham’s Razor’, to strive to an optimum
> in
> > simplicity will be
> > strongly violated.
> >
> > Your next remark:
> >
> > **You conclude that "the existence of two sound
> energy
> > transport phenomena
> > with different transfer velocities within this tiny
> cochlear
> > volume of
> > perilymph fluid as suggested by Lighthill is
> impossible." Yet
> > all
> > observations do see a slow wave, much slower than
> the speed of
> > sound, and
> > basic mathematical physics of the same sort that has
> been
> > working well for
> > over 100 years to describe waves in fluids predicts
> exactly
> > that behavior.
> > Some may quibble that it has not been conclusively
> proved that
> > the observed
> > slow wave carries energy; but no workable
> alternative has been
> > put forward,
> > and no experiment convincingly contradicts this main
> > hypothesis of the
> > current paradigm, as far as I know. I know some on
> this list
> > will probably
> >
> > say I'm wrong, now that I've opened the door.**
> >
> > Do you agree with me that the perilymph inside the
> cochlear
> > duct, existing
> > of scala vestibuli and scala tympani, is just moving
> back and
> > forth over
> > distances not exceeding a few micrometer?
> >
> > If you admit this fact, you should also agree with
> me that all
> > the known
> > and involved physical quantities and parameters
> indicate that
> > we are
> > confronted here with the problem to find the
> hydrodynamic
> > solution for the
> > non-stationary small movements of an incompressible
> > non-viscous fluid in a
> > tiny narrow duct.
> > According to the rules of physics it is then
> permitted without
> > any
> > additional constraints to use the non-stationary
> Bernoulli
> > equation.
> >
> > The exact and detailed solution of this equation I
> can – if
> > you wish – send
> > you separately.
> >
> > The result is exactly the mathematical _expression_ I
> have used
> > in the
> > booklet: the pressure decrease in the perilymph
> duct in front
> > of the
> > basilar membrane is everywhere proportional to the
> perilymph
> > velocity
> > squared.
> > What leads to the overall result that the pressure
> stimulus on
> > the basilar
> > membrane is proportional to the sound energy
> stimulus offered
> > to the ear.
> >
> > You further wrote:
> >
> > **Yet all observations do see a slow wave,
> much
> > slower than the
> > speed of sound.**
> >
> > Indeed, an observation of a ‘slow wavy movement’ and
> the only
> > place where
> > we can observe this is the basilar membrane.
> >
> > It isn’t the occurrence of a wavy movement
> phenomenon that we
> > have to
> > discuss. It is the origin of that ‘traveling wave’
> that we
> > have to
> > discover. Is it a vibration energy transporting wave
> or is it
> > a phase wave,
> > originated out of the manner in which the resonators
> in the
> > basilar
> > membrane are grouped?
> >
> > By the way, that is also – but not in an extended
> way –
> > explained in our
> > booklet. In that chapter of the booklet I describe
> why those
> > ‘waves’ always
> > run from base to apex. It is conform to the peculiar
> mechanics
> > of the
> > basilar membrane system that this phase wave
> behavior is
> > prescribed as it
> > is.
> > And that mathematical solution for this mechanics
> problem of
> > resonators –
> > in case of the logarithmical frequency distribution,
> low near
> > the apex to
> > high near the base – can be calculated, as I have
> done,
> > analytically for a
> > pure sinusoidal tone, which exactly results in a
> tonotopical
> > symmetrical
> > envelope of that running phase wave with center
> frequency
> > equal to the
> > corresponding resonance frequency.
> > And the running direction of that phase wave is
> always from
> > base to apex.
> > Exactly as Tianying Ren has reported in his then
> speech making
> > paper that I
> > have cited:
> >
> > Ren T. (2002) Longitudinal pattern of basilar
> membrane
> > vibration in the
> > sensitive cochlea. Proc Nat Acad Sci USA 99:
> 17101-6.
> >
> > The animation of such a phase wave can be seen in:
> >
> >
>
http://www.a3ccm-apmas-eakoh.be/aobmm/bm-movement.htm
> >
> > You wrote:
> >
> > **It sounds like you're trying to get away from a
> > Helmholtz-like conception
> > of resonators or places responding to frequencies,
> and replace
> > it with a
> > more time-domain approach that works for a lot of
> pitch
> > phenomena. But it
> >
> > will work better to put that time-domain mechanisms
> AFTER the
> > what the
> > cochlea does. Each hair cell is a "tap" on the BM,
> reporting
> > a time-domain
> > waveform as filtered by the traveling-wave
> mechanism; that's
> > where the
> >
> > pitch-processing nonlinear time-domain operations
> start...**
> >
> > As you already have indicated in the beginning, you
> haven’t
> > studied the
> > booklet entirely. I know for sure that by not
> studying the
> > booklet
> > entirely, you have drawn premature conclusions here.
> >
> > It is quite on the contrary. I think that I have
> explained
> > clearly enough
> > in the booklet that everywhere along the basilar
> membrane very
> > local
> > resonance with a high quality factor takes place.
> However not
> > on the
> > primary sound pressure signal, but on the sound
> energy signal.
> > Next to that
> > the basilar membrane will react everywhere – but not
> in a
> > resonance mode
> > and therefore with much smaller displacements – and
> will show
> > a response on
> > other frequency components, including utmost low
> frequencies
> > even until
> > stationary pressure signals.
> >
> > And for the explanation of our hearing sense I don’t
> need a
> > time domain
> > mechanism at all.
> > In the new paradigm, described by me, from all the
> > distinguishable
> > frequencies next of course to their frequency also
> their
> > individual
> > amplitude and phase are transmitted to the auditory
> cortex.
> >
> > Our brain can directly compare the entire frequency
> selected
> > sound energy
> > stimulus with patterns that are stored in our
> memory.
> >
> > Actually I cannot imagine a much more simpler and
> faster way.
> >
> > Finally about the definition of Ockham’s Razor –
> also spelled
> > Occam – I
> > found on the Internet the following physics
> educational
> > website:
> >
> >
>
http://math.ucr.edu/home/baez/physics/General/occam.html
> >
> > where among others a number of stronger but clear
> definitions
> > are given,
> > and I cite:
> >
> > *** If you have two theories that both explain the
> observed
> > facts, then you
> > should use the simplest until more evidence comes
> along.
> >
> > The simplest explanation for some phenomenon is more
> likely to
> > be accurate
> > than more complicated explanations.
> >
> > If you have two equally likely solutions to a
> problem, choose
> > the simplest.
> >
> > The explanation requiring the fewest assumptions is
> most
> > likely to be
> > correct.
> >
> > . . .or in the only form that takes its own
> advice. . .
> >
> > Keep things simple! ***
> >
> > Within this framework I am convinced that I have
> done my
> > utmost best.
> >
> > So I am awaiting for a much better explanation for
> the
> > described beat
> > phenomena based on the current hearing paradigm.
> >
> >
> > Kind regards,
> >
> > Pim Heerens
> >
>
>
>
>