10 ROOM MEASUREMENT
Once the speakers and subwoofers have been calibrated, their
anechoic response has been corrected in both frequency and
time. When placed in a room, however, reflections and
resonances in the room act to degrade the frequency response.
To correct for the effects of the room, the DEQX uses parametric EQ, described in
Chapter 12. As a starting point for room EQ, a room measurement is necessary – that is,
the response of the speakers (and subwoofers) when measured from the listening
position. Room measurements are also used to integrate the subwoofers (if used) with
the main speakers.
When taking room measurements, the speakers and subwoofers are positioned in their
regular locations. If you are still experimenting with the best locations for the speakers
or subwoofers in the room, be aware that you will need to redo your room
measurements and EQ each time you move the speakers or subwoofers. The room
measurement can in fact be used to help you determine the optimum locations for
speakers and subwoofers.
It is important to be aware that room measurements show the response not only of the
speakers and subwoofer(s) but also the effect of a long series of resonances and
reflections in the room. They are very different in nature to the anechoic and nearfield
measurements taken in earlier chapters. There is no such thing as a “clean” room
measurement.
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