# Re: harmonic extraction

Please pardon the brevity of my previous post.

I also noticed, while using an "exciter" effect, which adds harmonics to
a signal that, in the presence of a signal with many even harmonics,
I can't hear the addition of odd harmonics.  My knowledge in this area
is not extensive but I can think of a possible explanation:

Successive in-phase addition of even harmonics produces a square
wave.  Successive in-phase addition of odd harmonics yields a
triangle wave. A square wave has much more power than a triangle
wave of the same peak amplitude so you have more signal.

Absorptive and dispersion losses are greater at higher pressure,
not higher power. So triangle waves, composed of odd harmonics,
lose a greater portion of their power to non-resonant or damped
systems, cavities and membranes with partially absorptive components
or boundaries.  Speakers, headphones, ears, and air all contain
partially absorptive components.

If you lop off the top of a triangle wave you end up with something
closer to a square wave, a signal which sounds like it has been built
with in-phase even harmonics.

Signals composed of components with partial phase differences
would be more complicated.  I have not considered them.

Dave Smith
----- Original Message -----
From: "Al Bregman"
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: [AUDITORY] harmonic extraction
Date: Thu, 26 Mar 2009 11:51:32 -0400

On Thu, Mar 26, 2009 at 9:58 AM, David Smith wrote:

> Given the stimuli, I think you would be hard pressed to find a mechanical
> system,
> the atmosphere and ear included, which did not exhibit response at 200Hz.

Dear David,

Please expand on this. It's not clear how you intend this to explain
Jim Bashford's observations.

- Al
----------------------------------------------------------

> ----- Original Message -----
> From: "Al Bregman"
> To: AUDITORY@xxxxxxxxxxxxxxx
> Subject: Re: [AUDITORY] harmonic extraction
> Date: Wed, 25 Mar 2009 12:46:37 -0400
>
>
> Dear James,
>
> This example of duplex perception, outside the domain of speech, and
> clearly not involving two distinct mental "modules", is very
> interesting, throws a different light on duplex perception of speech,
> and is certainly worth further development and publication..
>
> Best,
> Al
> -------------------------------------------------------------------
> Albert S. Bregman, Emeritus Professor
> Psychology Department, McGill University
> 1205 Docteur Penfield Avenue
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>
> On Wed, Mar 25, 2009 at 10:35 AM, James Bashford wrote:
>> Dear Xueliang Zhang,
>>
>>    I was intrigued by the interchange between you, Yoshitaka Nakajima, and
>> Al Bregman, and did some listening, diotically through headphones, to
>> stimuli consisting of the first 10 harmonics of 100 Hz alternating with
>> the
>> 5 even harmonics of that stimulus (all harmonics were presented at the
>> same
>> level).  With on/off times for each complex matched at either 0.5 sec or
>> 1.0
>> sec (10 ms rise/fall), I hear a fully continous 200-Hz tone that matches
>> the
>> intensity and timbre of the isolated even-harmonic complex.  More
>> interesting, however, is that the 10-component “all-harmonic” stimulus,
>> which is heard intermittently, has not only the 100-Hz pitch of that
>> complex
>> but also retains the loudness and timbre of the all-harmonic stimulus as
>> heard when it is presented in isolation.  Were the even harmonics of the
>> all-harmonic complex exclusively allocated to support perception of the
>> continuous 200-Hz complex tone -- leaving only the odd-harmonics to
>> support
>> perception of the 100 Hz tone -- we would expect both a reduction in
>> loudness and a clear shift in timbre to the “hollow” quality
>> characteristic
>> of odd-harmonic signals.  This suggests that the “priming” or “capture”
>> effect observed with complex tones provides an example of duplex
>> perception
>> that requires neither a verbal stimulus nor dichotic presentation.  As I
>> recall, Al Bregman has previously suggested that such an effect might
>> occur
>> when nonverbal stimulus input is strongly ambiguous.
>>
>>       This use of the even-harmonic components to support two simultaneous
>> percepts (that of both the intermittent “all-harmonic” tone and the
>> continuous even-harmonic tone) contrasts sharply with the processing
>> underlying the general phenomenon of illusory continuity that is observed
>> when one sound alternates with a higher-intensity, potential masking
>> sound.  The latter effect, which has been called auditory induction
>> (Warren,
>> 1972), occurs with a wide variety of signals, such as tones alternating
>> with
>> other tones, noise alternating with higher intensity noise, or speech
>> interrupted by noise (phonemic restoration).  This type of continuity, in
>> which there are no exactly matching components to be found between the
>> alternating signals, does appear to involve subtractive or exclusive
>> allocation.  For interrupted tones, noise, or speech, continuity is
>> obtained
>> at the expense of the interrupting signal, which is reduced in loudness by
>> an amount proportional to the extent the illusion (Warren et al., 1994).
>>
>> Warren, R. M., Obusek, C. and Ackroff, J. M. (1972). Auditory induction:
>> Perceptual synthesis of absent sounds. Science, 176, 1149-1151.
>>
>> Warren, R. M., Bashford, J. A., Jr., Healy, E. W., and Brubaker, B. S.
>> (1994). Auditory induction: Reciprocal changes in alternating sounds.
>> Perception & Psychophysics, 55, 313-322.
>>
>>
>>
>> James Bashford
>>
>> On Mar 19, 2009, at 5:24 AM, xlzhang wrote:
>>
>> Dear list,
>> A pure tone can extract corresponding harmonic from complex sound when
>> appearing alternatively. I wonder if a harmonic sound can do the same job?
>> For example, a complex sound with F0=200Hz appears with a complex sound
>> with F0=100 Hz, can we get a continuous perception for F0=200Hz?
>>
>> Xueliang Zhang
>>
>>
>
>
>
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Albert S. Bregman, Emeritus Professor
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