[jayt]

hey all, I was directed to this site from headwize.com because they told me you guys might be able to help me with my question...

What are the tests that acoustics engineers perform on headphones to create a basis for comparison between brands and models, and to get quantitative information like frequency response, similarity to free-field and diffuse-field equalization, etc, etc? I've heard that the tests can involve artificial ears or heads, with small condenser mics inside; I'm not sure about that though.

I'm a student at the University of Washington getting a degree in Physics, and I was hoping to emulate some of these tests for my undergraduate research, so if anyone can give me pointers towards the procedural end of the testing, I'd be thrilled.

 

[mbriant]

Somewhere, I have a couple of old back issues of Sound & Vision magazine (Canada) which have an extensive article on headphone design and testing in them. One of the interesting things I recall from the article is that headphones are not designed to test out with a perfectly flat frequency response. The frequency response must be adjusted to compensate for the lack of outer ear influences.

If and when I find the article, I'll post it here.

 

[jayt]

just lemme know when you post them - thanks a ton! (if you want to get in touch off-list, i'm jayt@u.washington.edu)

 

[Budgie]

Your right on the money, Jayt. A fake ear is used with a lab mike capsule at the same point as the ears drum. It is mounted to a plate that allows a "close to head shaped"surface to provide the correct seal for the phones. From that point on the testing is essentially the same as testing a speaker (near field).Software driven measurement system such as Audio Precision is used. I don't know if a simple sweep is used or an FFT measurement. (Can't really see why a FFT would be necesary in a closed enviroment but I sure as hell aint no expert).