# Using REW to measure headphone SPL.



## Chrisbee (Apr 20, 2006)

Hi

An unusual question: How does one measure the actual dB at the ear from headphones? 

Can one just place the microphone of the Galaxy SP meter up against the headphone diaphragm set to C-weighting and feed the headphone with REW's pink noise? 

Or is there rather more to it?

Is there any difference in technique between measuring open, closed and in-ear headphones?

I'm not looking for fractions of a dB just curious about real levels as heard by the ear.


----------



## Snatcher (Jan 8, 2007)

It would imply using a more static setup, and you wouldn't get accurate measurements since you are not reproducing the conditions. I've read that some use a model of a head with ear canals and the mics in there to measure the response.

But to have at least a decent setup I'd say that you at least need to hang the headphones and place the mic in the middle.. but even that would be very far from reality.


What I actually used it for was a headphone amplifier =)


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

> Can one just place the microphone of the Galaxy SP meter up against the headphone diaphragm set to C-weighting and feed the headphone with REW's pink noise?


As Snatcher noted, measuring headphones is tricky. The reason is that they must couple with your head to get what you perceive as full-range response. Without the bass reinforcement you get with head-coupling, C-weighting won’t get you anything more than A-weighting will.

To get some idea of what C-weighted response would be, with a pink noise signal, I’d try setting the meter to A-weighting, and putting it against the diaphram. Then, turn on your main speakers, and set them at the same SPL reading you registered. Once you get the speakers at that level, switch the meter to C-weighting. No guarantees as to the accuracy of this recommendation, but it’s probably better than nothing.

Regards,
Wayne


----------



## Chrisbee (Apr 20, 2006)

Thanks. I'm beginning to think some form of shallow enclosure around the microphone is important even when testing open designs like the foam pad Sennheisers. Even something as simple as a shallow plastic funnel shape that fits over the microphone section might be enough.


----------



## Snatcher (Jan 8, 2007)

The guys from head-fi suggested using the carton tube from toilet paper cut in half. I've used that with my Grado SR 225s to measure different sources and amps at the same volume while playing 0 db 1khz test tones... but maybe it will not be optimal for your needs, it costs nothing to test after all.


----------



## Chrisbee (Apr 20, 2006)

Snatcher said:


> The guys from head-fi suggested using the carton tube from toilet paper cut in half. I've used that with my Grado SR 225s to measure different sources and amps at the same volume while playing 0 db 1khz test tones... but maybe it will not be optimal for your needs, it costs nothing to test after all.


Thanks, Snatcher. 

Provided the microphone is sealed to the tube and it is kept reasonably short I imagine this would work. I'll give it a try before I try anything more complicated.


----------

