Acoustic Measurement Primer – Room / Speaker Calibration

How to Test & Tune Your Room Acoustics

 
Frequency response dip / null caused by speaker-boundary interference response (SBIR)

Frequency response measurement showing a dip / null caused by the speaker-boundary effect.


 

Optimizing speaker placement with acoustic measurements & speaker calibration


If you can’t flush mount your speakers in the wall, you will need to experiment to find the optimum placement.

Use one of the these guidelines as a starting point (speakers close to wall or far from wall). At each location you try, do a critical listening test (with your ears) and take measurements of the low frequency response of your room (you can do this using Room EQ Wizard).

Here are measurement techniques you can use to ensure your monitors are calibrated for your room.

To shoot your room you will need a small diaphragm omnidirectional condenser microphone. It should have a relatively flat frequency response and fast transient response. A test microphone is your best bet.



The Behringer ECM8000 is a very economical option. If you’re looking for a premium measurement microphone, DPA and Earthworks make mics with fantastic accuracy. You can also use these reference microphones in the studio to record sound sources with exceptionally high transparency.

    The best listening position and speaker placement will have to balance multiple criteria:

  • The layout of speakers and listener must be practical. Your studio should be comfortable and have good workflow. Your hi-fi listening room or home theater should be comfortable, with a convenient layout.
  • Early reflections should be minimized to allow accurate imaging.
  • Low frequency problems (caused by room modes and boundary interference) should be minimized.

Speaker placement optimization requires a lot of acoustic measurements, and patience. If you’re up to the task, here is an optimization strategy recommended by acoustician Bogić Petrović (known as “boggy” on Gearslutz). Here are further testing guidelines by DanDan and Jens Eklund.

Run many tests using small increments (e.g., 6 inches). Reduce that to 2 inch increments when you start to narrow down on your optimal placement.

If you need assistance with acoustic measurements, optimizing speaker placement and selecting acoustic treatments, consider a professional room acoustics analysis.





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by Tim Perry