> On 23 April 2013 21:05, Matthew Palmer <palme...@mymail.vcu.edu> wrote: > > Thanks for the heads-up. Which mics do you use? > >
My 2 cents worth. For binaural recording I have used the Bruel and Kjaer type 4101 setup: http://www.bksv.com/products/transducers/acoustic/binaural-headsets/4101.aspx It's a sort of stethoscope-like arrangement with two matched DPA 4060 capsules located at the ear canal entrances. I mention the 4101 because it brings up a number of important points, even though it is financially out of range for most applications. The capsules are very small, so they can be located at the ear canal entrance and yet not block the entrance of sound so the user can still hear. B&K provides calibration information which allows you to equalize the resultant recording to get the correct diffuse-field response. About 30 years ago Gunther Theile, et al, worked to have a flat diffuse-field response be designated as the correct response for headphones. http://www.aes.org/e-lib/browse.cfm?elib=5233 But for binaural the key is to have the response measured at or in the ear canal be the same as what would have been experienced had the listener be present in the original recording environment. If we use miniature omni microphones with flat free-field response for binaural recordings then the spectral response at the ear canal entrance won't be flat, either if measured in the free-field or if measured in a diffuse field. And even headphones which are specified to have flat diffuse-field response don't really have flat diffuse-field response. But if we play back a particular binaural recording then what we would like to have happen is to have the spectrum measured with the binaural microphones at the user's ear, when playing back the binaural recording, be the same as what is on the recording. So if the headphones have, say a rising response, we can EQ that out in order to achieve the same response as in the recording. All of this makes a great deal of difference in what is heard. Of course we'd like to be able to transmit that recording from person to person and have everyone hear the same thing. But that won't happen because headphones differ so much. Nonetheless, good binaural recordings tend to sound striking when played back over good headphones regardless of the fact that the headphones aren't all the same. It's worth noting here that the concept that having a flat diffuse-field response for headphones is the best thing is under some debate at present. A paper to be presented at the upcoming 134th AES convention should have some interesting new data: http://www.aes.org/events/134/papers/?ID=3474 Listener Preferences for Different Headphone Target Response Curves—Sean Olive, Harman International - Northridge, CA, USA; Todd Welti, Harman International - Northridge, CA, USA; Elisabeth McMullin, Harman International - Northridge, CA USA There is little consensus among headphone manufacturers on the preferred headphone target frequency response required to produce optimal sound quality for reproduction of stereo recordings. To explore this topic further we conducted two double-blind listening tests in which trained listeners rated their preferences for eight different headphone target frequency responses reproduced using two different models of headphones. The target curves included the diffuse-field and free-field curves in ISO 11904-2, a modified diffuse-field target recommended by Lorho, the unequalized headphone, and a new target response based on acoustical measurements of a calibrated loudspeaker system in a listening room. For both headphones the new target based on an in-room loudspeaker response was the most preferred target response curve. Convention Paper 8867 More about ambisonic recording in a subsequent email. Eric Benjamin _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
