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Re: Headphones for virtual acoustics
- To: AUDITORY@xxxxxxxxxxxxxxx
- Subject: Re: Headphones for virtual acoustics
- From: "Bernhard U. Seeber" <seeber@xxxxxxxxxxxxxxxxxxxx>
- Date: Wed, 14 Dec 2005 11:53:56 -0800
- Delivery-date: Wed Dec 14 15:55:05 2005
- In-reply-to: <AUDITORY%200512140003224260.DE0E@LISTS.MCGILL.CA>
- References: <AUDITORY%200512140003224260.DE0E@LISTS.MCGILL.CA>
- Reply-to: "Bernhard U. Seeber" <seeber@xxxxxxxxxxxxxxxxxxxx>
- Sender: AUDITORY Research in Auditory Perception <AUDITORY@xxxxxxxxxxxxxxx>
- User-agent: Mozilla Thunderbird 1.0 (X11/20041207)
As previously suggested, equalization of headphones will (theoretically)
do the job. However, if you are using short FIR-filters for the HRTFs
the ability to equalize large, sharp, local spectral transitions will be
limited, but those transitions might occur due to resonances.
Additionally, bear in mind that equalizing the spectrum by +/-10dB
equals a power factor of 100 between min and max, which can get you
quickly into dynamic range or nonlinearity problems with your playback
To limit the amount of equalization many people use diffuse field
equalized headphones which more or less resemble the average HRTF from
all directions. Since this also "sounds good" most consumer headphones
follow the diffuse field equalization to some degree. The widely used
Sennheiser HD580 is in that category and it works well with HRTFs. Two
headphones that I know of are manufactured to stringent diffuse field
specs: the STAX Lambda Pro with a special driver, and the AKG 240DF. The
first one is an expensive, but amazing electrostatic headphone. The AKG
240DF is relatively cheap, manufactured to diffuse field specs, and
works reasonably well with HRTFs. Sennheiser/Head Acoustics also make an
electrostatic system for virtual acoustics.
Some other questions which you might want to think about:
- Do your headphones also have to be approved for audiometric measurements?
- Do you want them to be in production 10 years from now with the same
- Do you want to use several headphones of the same type, all with
identical specs? Consumer grade headphones may not fulfill this
requirement because design changes might be introduced during the
production run. To get around this you can buy several of them at once
from the same batch.
With respect to headphone placement variability I can't judge these
headphones in comparison to others.
I hope this helps a bit, good luck!
Dr.-Ing. Bernhard U. Seeber
Department of Psychology office: +1 510-643-8408
University of California, Berkeley lab: +1 510-642-5352
3210 Tolman Hall #1650 fax: +1 510-642-5293
Berkeley, CA 94720-1650, USA web: http://www.bseeber.de
Date: Tue, 13 Dec 2005 10:19:32 +0100
From: Bernhard Laback <Bernhard.Laback@xxxxxxxxxx>
Subject: Headphones for virtual acoustics
We are looking for headphones to present virtual sound sources by
filtering stimuli with HRTFs. They should have 1) a flat frequency
response up to about 18kHz and b) high reproducibility of sound
intensity - particularly at high frequencies - when putting the
headpnones off and on again.
We currently use the Sennheiser HDA200, which appear to fulfill the
second requirement but not the first one.
Can anyone recommend a device fulfilling both requirements?