Operation Manual

5.3 The FX View 39
Amplitude (dB)
Frequency (Hz)
0dB
−3dB
Center
Frequency
Band Width (Q=1)
Figure 20: Frequency response of a notch filter.
since we always listen to instruments in a room and thus with a room effect.
Impulse Response of a Room
The best way to evaluate the response of a room is to clap hands and to listen to the resulting
sound. Figure 21 shows the amplitude of the impulse response of a room versus time. The first
part of the response is the clap itself, the direct sound, while the remaining of the response is the
effect of the room which can itself be divided in two parts. Following the direct sound, one can
observe a certain amount of echoes which gradually become closer and closer until they can not be
distinguished anymore and can be assimilated to an exponentially decaying signal. The first part
of the room response is called the early reflexion while the second is called the late reverberation.
The total duration of the room response is called the reverberation time (RT).
Adjusting the room effect
The size of a room strongly affects the reverberation effect. The Size selector is used to choose be-
tween the Studio, Club, Hall and Large Hall settings each reproducing spaces of different volumes
from smaller to larger.