Re: Thompson's "On Binaural Audition"

There is a trick to extract each page to a png image and then make a pdf from the set of images. Please let me know if you need any help.

For what it is worth, I was destined to be a mathematician after my father gave me a copy of Silvanus P Thompson’s “Calculus Made Easy” for my 14^th birthday. It is available online at the Gutenberg Free Press.

Regards

Tilak

J T Ratnanather DPhil

Associate Research Professor

Center for Imaging Science and Institute for Computational Medicine

Department of Biomedical Engineering

The Johns Hopkins University

Baltimore MD 21218

From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Richard F. Lyon
Sent: Tuesday, November 03, 2015 2:11 PM
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: Thompson's "On Binaural Audition"

It turns out these papers are free online in Google Book search, which is where HathiTrust got their copy that a reader kindly sent me.

1877: On Binaural Audition: https://books.google.com/books?id=DVUEAAAAYAAJ&pg=PA274#v=onepage&q&f=false

1878 Part II: https://books.google.com/books?id=_ZpJAQAAMAAJ&pg=PA383#v=onepage&q&f=false

1881 Part III: https://books.google.com/books?id=-hlKAQAAMAAJ&pg=PA351#v=onepage&q&f=false

There are so many references to them that it's hard to find them in Google Book Search. Also OCR errors don't help (like Sylvantis).

Restricting the search date range sometimes helps, but it's still sporadic whether they get found or not. Very odd.

Dick

On Sun, Nov 1, 2015 at 1:59 PM, Richard F. Lyon <dicklyon@xxxxxxx> wrote:

Three people sent me copies and I've sent copies to 4 people who requested them.

These are definitely in the public domain in the US at least (or so the cover page states),

so if anyone else wants a copy, just ask me.

I was particularly interested because of what Wilson and Myers said in 1908 about the "unwelcome hypothosesis" that phase could be compared centrally:

"... Thompson concluded that under the conditions of binaural hearing above described, the tone-stimulus is transmitted along each auditory nerve to some common cerebral centre and that at this centre the beats arise. But this and the following interesting fact, also observed by Thompson, can be explained without recourse to such an unwelcome hypothesis, if we suppose that each tone is transmitted by bone conduction to the opposite ear and that the beats heard are due to the play of the two series of vibrations of different frequency on one and the same sense organ"

I wondered if Thompson really proposed such an "unwelcome hypothesis", a central comparison of waveforms from the two sides. What I find it that he rather carefully danced around the idea, suggesting it but not saying it, and trying to rule out bone conduction, in 1877:

"5. It is not easy to explain why interference-beats should thus occur in the simultaneous individual action of the two ears, while combinational tones (difference-tones) are inaudible. There is in the case of the auditory nerves, or portio mollis, no decussation like that of the optic nerves; the former do not intersect after leaving the fourth ventricle, in which they have their common origin, and from which they diverge ri ht and left. _ There is in health a possible communication between the ears across the pharynx, through the Eustachian tubes. Moreover the bone of the skull itself is capable of conveying sonorous tremors, which might account for both ears hearing a sound entering by one only. In either of these latter cases, however, there would be no reason why combinational tones should not be equally audible in binaural as in monaural audition; so that we are driven to the hypothesis that any means of comparison which may exist in the nerve systems of the ears exists deep-seated in the actual structure of the brain. This may be the reason why dissonances are in binaural audition so excessively dis agreeable, and why even ordinary consonant intervals become harsh. They evoke a discontinuous sensation when there is no opportunity of their blending previously to acting upon the sensitive mechanism of the nerve-structures. The discontinuity of the sensation produces an intensity of effect exceeding that of a continuous one. Hence sounds all but in audible themselves may yield, as noted in No. 2, very well marked beats, enabling the ear thus to detect the most delicate differences of tone.

and again in 1878:
"There is no decussation of the auditory nerves, like that of the optic nerves, to account for a blending of the sensations. The portio mollis of the right does not intersect or have any commissure with the portio mollis of the left after leaving the fourth ventricle of the brain, from which they originate. This point deserves the attention of anatomists and physiologists."

He seems to neglect the possibility that the signals could be compared in the brainstem (where we now know the olivary complex does just that).

On Sat, Oct 31, 2015 at 9:10 AM, Richard F. Lyon <dicklyon@xxxxxxx> wrote:

Thanks, got them!

Dick

On Fri, Oct 30, 2015 at 4:03 PM, Richard F. Lyon <dicklyon@xxxxxxx> wrote:

Does anyone have copies of Sylvanus P. Thompson's articles "On Binaural Audition" and its follow-on "Phenomena of binaural audition—Part II" in Philosophical Magazine?

These would seem to be in the public domain, but the only copies I can find online are for sale at an exorbitant rate:
1877: http://www.tandfonline.com/doi/abs/10.1080/14786447708639338?journalCode=tphm16
1878: http://www.tandfonline.com/doi/abs/10.1080/14786447808639528?journalCode=tphm16
Dick