The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Gear for sale  Search Gearslutz Go Advanced
Question about proximity from mic when measuring Studio Headphones
Old 31st December 2010
  #1
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
  #2
Gear Guru
 
Ethan Winer's Avatar
 

Lightbulb

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.

--Ethan

________________
The Acoustic Treatment Experts
Old 31st December 2010
  #3
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....

Cheers

Kris
Old 31st December 2010
  #4
SAC
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
  #5
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
  #6
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.

DD
Top Mentioned Products
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Similar Threads
Thread
Thread Starter / Forum
Replies
tturner / So much gear, so little time
3
rogerbrain / So much gear, so little time
3
chazwood / Mastering forum
8
hakim / So much gear, so little time
10

Forum Jump
Forum Jump