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!