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Acoustic Response of a Room

Measuring the acoustic response will enable you to properly adjust the equalizer settings on your sound system for optimum performance.  A typical procedure is described below:

Key Settings: 
Amplitude axis:  Logarithmic
Frequency Resolution:  1/3 Octave
Standard Weighting:  Flat
Sampling rate:  44100Hz
Averaging size:  Forever
Signal Generator Pink Noise

  • Set your sound system equalizer settings to zero or take it off line.
  • Connect the signal generator to the input of your sound system.
  • Place the measurement microphone in the center of the room.
  • Adjust the sound card input gain and/or sound system output gain as needed
  • Run the analyzer and examine the spectrum.  Stop the analyzer when the averaged spectrum response has settled sufficiently.

    Interpret the results:
    An acoustically "flat" room will produce a perfectly flat spectrum.  In this instance, we are not concerned so much with the absolute values of the spectrum as with their relative response.  Each 1/3 octave band corresponds to a slider on your 1/3 octave equalizer.  Simply adjust the sliders on your equalizer to compensate for the acoustic response of the room.  You may wish to run a second test to verify the results.  

    Narrowband frequency response (optional):
    One limitation of 1/3 octave analysis is that each band represents a rather wide span of frequencies.  If narrowband frequency components are present, 1/3 octave analysis lacks sufficient resolution to detect these components.  Set the frequency Resolution to Narrowband and substitute white noise instead of pink and repeat the measurement above.