Re: Outer ear transfer function measured with headphones.

[Henrik Møller <hm@xxxxxxxxxx>]

"Enrique A. Lopez-Poveda" wrote:

> Dear list,
>
> I am looking for a reference that provides the acoustic transfer function
> of the pinna measured through headphones. That is the response at the
> eardrum of an ideal click delivered through headphones. In particular, I
> am interested in the response with Sony MDR-V6 headset. Can point me
> to (or better provide) any useful reference?
>
> Thank you very much in anticipation.
>
> - Enrique
>
> --
> Dr. Enrique A. Lopez-Poveda
> Facultad de Medicina               Tel. +34-967599200 ext.2749
> Universidad de Castilla-La Mancha  Fax. +34-967599270 / 72 / 04
> Campus Universitario               http://emedica.med-ab.uclm.es
> 02071 Albacete -- Spain

Dear Enrique

We have done a lot of measurements in human ear canals - with a free field
sound source (to measure HRTFs) as well as with headphones. Some of the
headphone measurements are published in:

Henrik Møller, Dorte Hammershøi, Clemen Boje Jensen, Michael Friis Sørensen:
"Transfer characteristics of headphones measured on human ears", Journal of
the Audio Engineering Society, Vol. 43, No. 4, April 1995, pp. 203-217.

Unfortunately, the headphone you mention was not included.

Most of our measurements are not made at the eardrum. The reason is that
usually one wants - with the headphone - to mimic or simulate the
transmission of "something else", e.g. a transmission from an external sound
field. Thus we are not really aiming at a particular sound at the eardrum,
but only at the same sound as the "real" situations we are simulating. And,
since part of the transmission from the headphone and in the "real" situation

is physically the same (the ear canal), you can use other points in the ear
canal that are more easily accessible. At our lab. we use most often a
measurement point at the entrance to a blocked ear canal. This point is now
used by most people working in VR audio. You can find more details about the
theory in:

Henrik Møller: "Fundamentals of binaural technology", Applied Acoustics, Vol.

36, No. 3/4, 1992, pp. 171-218.

We also investigated how the theory could be used to set up design criteria
for headphones (rather than a flat frequency response measured at the
eardrum). This was reported in:

Henrik Møller, Clemen Boje Jensen, Dorte Hammershøi, Michael Friis Sørensen:
"Design criteria for headphones", Journal of the Audio Engineering Society,
Vol. 43, No. 4, April 1995, pp. 218-232.

If you intend to simulate the transmission from a free field, you might also
be interested in the following article on HRTFs and their measurement:

Henrik Møller, Michael Friis Sørensen, Dorte Hammershøi, Clemen Boje Jensen:
"Head-related transfer functions of human subjects", Journal of the Audio
Engineering Society, Vol. 43, No. 5, May 1995, pp. 300-321.

Sincerely,

Henrik Møller