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Room Reverberation
Acoustical Measurement
Room reverberation time can be calculated
from the room impulse response. Different metrics have been developed to quantify room
reverberation. The early decay time (EDT) evaluates the first 10 dB of the decay process
and correlates closely with the perception of reverberance. The T20 and T30 metrics assess
reverberation, respectively, for the -5 to -25 dB and -5 to -35 dB reverberant decay slopes.
The above graph is for a small recital hall with a deep balcony. The red diamond curve shows
a longer EDT in contrast to the shorter brown square T20 and green triangle T30 curves. The
poor acoustical coupling of the balcony to the main room volume is the primary cause for the
shorter T20 and T30 values compared to the EDT values. |
