2. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Electronics Principles & Applications Seventh Edition DSP Audio Examples (Ch. 16 supplement) Charles A. Schuler

3. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. The audio examples in this presentation were prepared using the GoldWave digital audio editor version 4.26. (www.goldwave.com) Click this icon to verify that your sound works.

4. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Square wave before filtering

5. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Square wave after low-pass filter

6. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. The GoldWave Device Controls panel Spectrum (1 kHz square wave) Spectrum (1 kHz sine wave)

7. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. HPF (2.7 kHz) LPF (500 Hz) 400 Hz Square wave Filtered wave (sine) Audio example (square wave and filters) Click the speaker icons to hear the sounds. The low-pass filter attenuates all harmonics higher than the 1 st (the fundamental). Filtered wave The high-pass filter passes the 7 th harmonic and all those above. BPF (2.0 kHz) Filtered wave (sine) The band-pass filter passes the 5 th harmonic

8. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. LPF (2 kHz) Voice Filtered Voice Audio example (voice and low-pass filter)

9. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. HPF (500 Hz) Voice Filtered Voice Audio example (voice and high-pass filter)

10. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. BPF 0.5 - 2 kHz Voice Filtered Voice Audio example (voice and band-pass filter)

11. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Voice Voice with echo Audio example (echo effect) An echo effect is created by adding delayed samples to the original signal. Delay

12. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Reverse Voice Reversed Voice Audio example (voice and reverse effect) The reverse effect flips the end of the sampled signal with the beginning (thus it plays backwards).

13. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Voice Noise Voice + Noise Audio example (voice + noise) LPF (2 kHz) The noise is broad band and a LPF only helps a little.

14. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. The importance of signal-to-noise ratio Very poor Very good

15. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Voice Clicks Voice + Clicks Audio example (voice + clicks) Click DSP The removal of clicks with DSP works very well.

16. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. 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-stop filter works very well but there is some ringing.

17. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Pitch higher Voice Altered Voice Audio example (voice and special effects) Pitch lower Altered Voice The pitch is changed by clocking the data to the D/A converter at a faster or slower rate.

18. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. SE #1 400 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!