# Documentation

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# Reverberator

• Library:
• Audio System Toolbox / Effects

## Description

The Reverberator block adds reverberation to mono or stereo audio signals. You can tune parameters of the Reverberator block to mimic different acoustic environments.

## Ports

### Input

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• Matrix input –– Each column of the input is treated as an independent channel.

• 1-D vector input –– The input is treated as a single channel.

Data Types: single | double

### Output

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The Reverberator block outputs a signal with the same data type as the input signal. The size of the output depends on the size of the input:

• Matrix input –– The block outputs a matrix the same size and data type as the input signal.

• 1-D vector input –– The block outputs an N-by-1 matrix (column vector), where N is the number of elements in the 1-D vector.

Data Types: single | double

## Parameters

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If a parameter is listed as tunable, then you can change its value during simulation.

Pre-delay for reverberation is the time between hearing direct sound and the first early reflection. The value of Pre-delay (s) is proportional to the size of the room being modeled.

Tunable: Yes

Lowpass filter cutoff is the –3 dB cutoff frequency for the single-pole lowpass filter at the front of the reverberator structure. It prevents the application of reverberation to high-frequency components of the input.

Tunable: Yes

Diffusion is proportional to the rate at which the reverb tail builds in density. Increasing Diffusion pushes the reflections closer together, thickening the sound. Reducing Diffusion creates more discrete echoes.

Tunable: Yes

Decay factor is proportional to the time it takes for reflections to run out of energy. To model a large room, use a long reverb tail (low decay factor). To model a small room, use a short reverb tail (high decay factor).

Tunable: Yes

High frequency damping is proportional to the attenuation of high frequencies in the reverberation output. Setting High frequency damping to a large value makes high-frequency reflections decay faster than low-frequency reflections.

Tunable: Yes

Wet/dry mix is the ratio of wet (reverberated) signal to dry (original) signal that your Reverberator block outputs.

Tunable: Yes

When you select this parameter, the block inherits its sample rate from the input signal. When you clear this parameter, you specify the sample rate in Input sample rate (Hz).

Tunable: No

Tunable: Yes

#### Dependencies

To enable this parameter, clear the Inherit sample rate from input parameter.

• Interpreted execution –– Simulate model using the MATLAB® interpreter. This option shortens startup time and has simulation speed comparable to Code generation. In this mode, you can debug the source code of the block.

• Code generation –– Simulate model using generated C code. The first time you run a simulation, Simulink® generates C code for the block. The C code is reused for subsequent simulations, as long as the model does not change. This option requires additional startup time but the speed of the subsequent simulations is comparable to Interpreted execution.

Tunable: No

## Algorithms

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The algorithm to add reverberation follows the plate-class reverberation topology described in [1] and is based on a 29,761 Hz sample rate.

The algorithm has five stages.

The description for the algorithm that follows is for a stereo input. A mono input is a simplified case.

## References

[1] Dattorro, Jon. "Effect Design, Part 1: Reverberator and Other Filters." Journal of the Audio Engineering Society. Vol. 45, Issue 9, 1997, pp. 660–684.

[2] Dattorro, Jon. "Effect Design, Part 2: Delay-Line Modulation and Chorus." Journal of the Audio Engineering Society. Vol. 45, Issue 10, 1997, pp. 764–788.