Subject: Re: Lateral Inversion in Spatial Hearing From: Heinrich Zimmermann <hzimmer(at)IAM.UNIBE.CH> Date: Tue, 8 Feb 2000 15:03:52 +0100"Houtsma, A.J.M." wrote: > > > > -----Original Message----- > From: Heinrich Zimmermann [mailto:hzimmer(at)IAM.UNIBE.CH] > Sent: zaterdag 25 september 1999 11:39 > To: AUDITORY(at)LISTS.MCGILL.CA > Subject: Re: Lateral Inversion in Spatial Hearing > > First Summary: Lateral Inversion in Spatial Hearing > > On September, 2nd, I have put the following query on this list: > > > I wonder if anybody on the Auditory List knows something about a lateral > > inversion phenomenon I discovered when preparing sounds for a series of > > experiments on spatial hearing: certain binaural recordings of > > bandpass-filtered clicks with interaural time differences but without > > interaural intensity differences seem to be lateralized as predicted by > > cross-correlation models in a frequency range below 2 Kilohertz but on the > > opposite side than predicted by these models in a frequency range above > > 8 Kilohertz. > > In response to some of your questions I have put an example sound file for > the lateral inversion phenomenon on http://Heinrich.Zimmermann.com > <http://Heinrich.Zimmermann.com> . > > > ------------------------------------------------------------------------ > Dear Heinrich, > > I listened to your sound sample and, indeed, the chirp apears to come from > the right. Analysis > of the sound, however, shows several confounding artifacts. > (1) There is an annoying ringing in the 'silent' portion of the signal > before and after the click, > particularly in the right channel. It is a mix of a 2-kHz and 8-kHz > tone, corresponding to > the edges of your extremely steep bandpass filter. This tone sets a > strong bias towards > the right ear and could explain the whole 'lateral inversion' > phenomenon. > (2) The right signal is not only 500 microsec. delayed, but also phase > distorted. Did you use > separate independent filters?. This phase distortion causes the image > to diffuse. > (3) Measured over the signal (click-response) portion, there is an intensity > difference of about > 0.5 dB between the signals, the left signal being the more intense. > > I therefore generated a somewhat cleaner signal this morning, starting with > an analog > 10-microsec. pulse bandpass filtered between 2000 and 8000 Hz by two Kemo > filters > in series (about 190 dB/oct). This signal was put in the left channel of a > stereo wav file. > In the right channel was either exactly the same signal (click.wav) or that > same signal > delayed by 500 microsec. (clickster.wav). Each file contains 5 clicks, 1 > sec. apart. If > you play them in this order, you will quite convincingly hear the first five > clicks in the > center and the next five clicks to the left of the center. Just as the > textbooks tell you. > > I have attached both files as wav attachments. Enjoy the clicks. > > Adrian Houtsma > > > ------------------------------------------------------------------------ > Name: click.wav > click.wav Type: WAV Audio (audio/x-wav) > Encoding: base64 > > Name: clickster.wav > clickster.wav Type: WAV Audio (audio/x-wav) > Encoding: base64