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Audio Flanging

This example shows how to apply a flanging effect and a stereo panning effect to an audio stream. A User Interface (UI) is used to control the audio effects. This interface plays the audio stream that contains the flanging and stereo panning effects. It displays the spectrograms of original and flanging audio streams.

This example also shows you how to process a continuous stream of data in MATLAB®. Processing frames of data avoids having to load the complete data at one time.

Introduction

Flanging, or "whooshing" sound is a type of phasing effect. To create it, you add the input signal to its delayed version while varying the delay over time. The following figure shows a block diagram implementation of flanging.

The stereo panner adds the effect of the audio signal moving from one speaker to the other.

See more information on audio effects [ 1 ].

MATLAB Simulation

HelperDspFlangerHelperDspFlanger is the function containing the algorithm's implementation. It instantiates, initializes and steps through the components forming the algorithm.

Execute HelperDspFlangerExecute HelperDspFlanger to run the simulation and plot the results on scopes. Note that the simulation runs for as long as the user does not explicitly stop it.

HelperDspFlanger launches a User Interface (UI) designed to interact with the simulation. The UI allows you to tune parameters and the results are reflected in the simulation instantly. For example, moving the slider for the 'Frequency of delay for flanging' to the right while the simulation is running, increases the frequency of the sine wave used to change the variable fractional delay over time. Similarly, moving the slider for the 'Stereo Panning' moves the audio signal from one speaker to the other. For more information on the UI, please refer to HelperCreateParamTuningGUIHelperCreateParamTuningGUI.

There are three buttons on the UI - 'Reset' and 'Pause simulation' are not used in this example, 'Stop simulation' ends the simulation. The interaction between the UI and the simulation is performed using UDP.

Results

We can clearly see the frequency changing over time in the spectrogram of the audio signal with flanging.

Summary

This example shows you how to implement the flanging audio effect using variable fractional delay applied to streaming data.

Selected Bibliography

  1. DAFX: Digital Audio Effects, edited by Udo Z�lzer, John Wiley & Sons, 2002.

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