ElectronicsElectronics

Principles & ApplicationsPrinciples & ApplicationsSixth EditionSixth Edition

DSP Audio Examples(Ch. 16 supplement)

©2003 Glencoe/McGraw-Hill

Charles A. Schuler

The audio examples in this presentation were preparedusing the GoldWave digital audio editor version 4.26.

(www.goldwave.com)

Click this icon to verifythat your sound works.

Square wave before filtering

Square wave after low-pass filter

The GoldWave Device Controls panel

Spectrum(1 kHz square wave)

Spectrum(1 kHz sine wave)

HPF(2.7 kHz)

LPF(500 Hz)

400 HzSquarewave

Filtered wave(sine)

Audio example (square wave and filters)

Click the speaker icons to hear the sounds.

The low-pass filter attenuates all harmonicshigher than the 1st (the fundamental).

Filtered wave

The high-pass filter passes the 7th harmonicand all those above.

BPF(2.0 kHz)

Filtered wave(sine)

The band-pass filter passes the 5th harmonic

LPF(2 kHz)

Voice Filtered Voice

Audio example (voice and low-pass filter)

HPF(500 Hz)

Voice Filtered Voice

Audio example (voice and high-pass filter)

BPF0.5 - 2kHz

Voice Filtered Voice

Audio example (voice and band-pass filter)

Voice Voice with echo

Audio example (echo effect)

An echo effect is created by addingdelayed samples to the original signal.

Delay Delay

ReverseVoice Reversed Voice

Audio example (voice and reverse effect)

The reverse effect flips the end ofthe sampled signal with the beginning

(thus it plays backwards).

Voice

Noise

Voice + Noise

Audio example (voice + noise)

LPF(2 kHz)

The noise is broad band and a LPF only helps a little.

The importance of signal-to-noise ratio

Very poor

Very good

Voice

Clicks

Voice + Clicks

Audio example (voice + clicks)

ClickDSP

The removal of clicks with DSP works very well.

BSF(1 kHz)

Voice

1 kHz sine

Voice + 1 kHz sine

Audio example (voice + 1 kHz sine)

The removal of an interfering tone with a band-stopfilter works very well but there is some ringing.

Pitchhigher

Voice Altered Voice

Audio example (voice and special effects)

Pitchlower Altered Voice

The pitch is changed by clocking the datato the D/A converter at a faster or slower rate.

SE #1400 Hz

square wave

Audio example (400 Hz square wave and special effects)

SE #2

SE #3

SE #4

If you can imagine it, DSP can probably do it!