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48 Parameters

Amplitude (dB)

Frequency (Hz)

0dB

−3dB

Center

Frequency

Band Width (Q=1)

Figure 30: Frequency response of a notch ﬁlter.

4.3.10 Reverb

The Reverb effect is used to recreate the effect of reﬂections of sound on the walls of a room or

hall. These reﬂections add space to the sound and make it warmer, deeper, as well as more realistic

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 31 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).

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APPLIED ACOUSTICS SYSTEMS STRINGSTUDIO Instrukcja Użytkownika Strona 48