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Question about proximity from mic when measuring Studio Headphones
Old 31st December 2010
Gear Maniac

Question about proximity from mic when measuring

What are the effects of being near the measurement mic when measuring your room? I ask because I notice that I'm usually only a couple of feet away.

A second question: I'm using REW and I notice a 1 sec delay before the sine sweep. Should I use this delay to scuttle away from the mic as fast as possible, or will my movements cause issues (I'm assuming this one sec delay is recording ambient noise or something?).
Old 31st December 2010
Gear Guru
Ethan Winer's Avatar


Assuming a typical stereo setup, if you're behind the microphone and off to the side by a foot or more that should be fine. Obviously you don't want to be between the microphone and any loudspeaker. And when measuring mid and high frequencies, reflections coming back from the rear wall should not be blocked since they can contribute to the measurement. So I'd say it's more a common sense situation, and just stay out of the direct line of fire as best you can.


The Acoustic Treatment Experts
Old 31st December 2010
Lives for gear
DrFrankencopter's Avatar
Here's some 'devil's advocate' food for thought:
Your body and head will absorb some of the high frequency reflections that will be captured by the mic. While this might appear to corrupt the mic measurement, they might also be something that you want to capture. For example, in an ETC analysis a reflection coming from an oblique angle might be absorbed by your body, and not require treating...

Maybe you should get yourself close to the mic for some measurements....


Old 31st December 2010
Registered User

You move out of the way of any and all energy transmissions/reflections.

There is no reason to be located close to the mic as tests are triggered from a computer that can be located away from the mic location either by cable or wireless connection.

If the computer is mounted such that it cannot be moved out of close proximity, as brilliant as this may seem for other purposes, it is a mistake in terms of measurement.
Old 31st December 2010
Gear Maniac

Yeah, I'm thinking of getting a USB extender cable so I can do my clicking from a distance. I can get clear of the mic before the sweep takes place, I was wondering if any noise during the preamble may cause problems. I did do some tests with me shouting throughout the entire test to see what excessive noise would do but for modal troubleshooting it doesn't seem to be much of a problem (not that I shout throughout the tests normally ). Ultimately I want to house the machine in a corner to the rear of the room as it was causing muchos comb filtering in my midrange.
Old 1st January 2011
Gear Guru
Body Reflection

Bruel and Kjaer state that we need to get well away from the mic, at least 1 Metre. Proximity behind the mic, as in holding an SLM, causes errors of around 6dB at about 400Hz.
P25 Measuring Sound (Primer/Handbook) Bruel and Kjaer.
The delay before sweep in REW and FM allows you to move away, as you described.
Happy New Year.

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