Re: Mike and Brad on Acoustic Flow Field Generation (Al Bregman )


Subject: Re: Mike and Brad on Acoustic Flow Field Generation
From:    Al Bregman  <al.bregman(at)MCGILL.CA>
Date:    Thu, 30 Aug 2001 14:24:55 -0400

Dear list, I recently have been suffering with a blocked right ear and have acquired some down-to-earth experience with spatial perception. In addition to noticing that all sounds seem to come from the side of my good ear, I have also experienced great difficulty in hearing sounds in reverberant environments (like Mike's hallway). Apparently auditory scene analysis (ASA) depends strongly on spatial cues for segregating the direct signal from reverberation. Possibly the typical recording of a loudspeaker does not adequately capture the spatial information (i.e., the spatial properties of the loudspeaker signal versus those of the reflections in the room) which would permit ASA to work effectively. This statement would imply that if the recording were done in stereo through an artificial head equipped with artificial pinnae, and played back over headphones that by-passed the pinnae of the listener, he or she would hear the loudspeaker as well from the recording as from being there in person. Al ------------------------------------------------- Albert S. Bregman, Emeritus Professor Dept of Psychology, McGill University 1205 Docteur Penfield Avenue Montreal, QC, Canada H3A 1B1 Office: Phone: +1 (514) 398-6103 Fax: +1 (514) 398-4896 Home phone & Fax: +1 (514) 484-2592 Email: al.bregman(at)mcgill.ca ------------------------------------------------- ----- Original Message ----- From: Bradley Wood Libbey <gt1556a(at)PRISM.GATECH.EDU> To: <AUDITORY(at)LISTS.MCGILL.CA> Sent: 30-Aug-01 8:57 AM Subject: Re: Acoustic Flow Field Generation > Mike, > > I have also noted degraded recordings from loudspeakers in enclosed > environments. When I record speech from a loudspeaker and then play this > recording back to a listener on headphones I find it to be less > intelligible than a person simply listening to the loudspeaker in the same > environment. Even though I took considerable pains to calibrate and > balance the recording and playback equipment. > > Unfortunately I don't have a direct answer, but in my case I suspect it is > related to imperfect recordings interacting with the acoustic environment. > For example the interaction of reverberation, noise, and the > directionality of the ears vs. microphones (in your case it may be related > to the directionality of the loudspeakers vs. human-speakers). I suspect > that better recording equipment and perfecting the > calibration/balancing/directionality of equipment might help and of course > reducing the noise. I would appreciate hearing about any answers you find > through your research. > > To close on a more interesting note, the listeners ability to localize a > source certainly must be important to the realness of the walking > sensation. I'm speculating that Doppler shift at walking speeds would > probably NOT be detectable for speech sounds especially considering the > reverberation in a hall, but it is a thought to ponder. What about > turbulent air flow noise over the pinna? > > Sincerely, > Brad Libbey > Georgia Institute of Technology > > > > > On Wed, 29 Aug 2001, Michael S. Gordon wrote: > > > Dear List - > > I am interested in capturing the acoustic flow field of a person walking > > down a hallway. Thus far I have made a couple of binaural recordings of (1) > > a perceiver walking past individuals reading text (live) and (2) a perceiver > > walking past a series of loudspeakers projecting an assortment of recorded > > sounds (e.g., human speech, typewriter clicks, etc.). Those who have > > listened to these recordings have found the first set a much more compelling > > indication of the listener╣s motion than the second. There are several > > reasons why this may have been the case: the live readers were fewer, more > > sparsely located, and generally louder than the recordings via loudspeakers. > > I am writing to the list because I was hoping that some of you might > > have some intuitions or know some references that would help guide me to > > more successfully capture the acoustic flow field of a person walking > > through a hallway. Specifically I am wondering whether live sounds should be > > easier to localize through a loudspeaker than recorded sounds? Furthermore > > should the localizability of the sound sources contribute to the Orealness╣ > > of the walking event for a listener? I would greatly appreciate any > > thoughts on this issue. > > > > > Respectfully, > > > Mike Gordon > > -- > > Michael S. Gordon > > Ecological Acoustics Laboratory > > Department of Psychology > > University of California, Riverside > > Riverside, CA 92521 > > USA > > 909-787-4579 > > mike.gordon(at)psych.ucr.edu > > http://www.psych.ucr.edu/faculty/rosenblum/Mike_Gordon/MikeGordon _home.html > > > > > > >


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