DSP PROJECT

1
DSP PROJECT

• Sound Effects Implementation in V. DSP

2
PROJECT GROUP
3
Contents

• Sound effects
• Our project
• Background techniques
• Applications
• Methodology
• Results
• Conclusion

4
Sound Effects

• artificially created or enhanced sounds
• Delay
• Multiple Echo
• All pass Reverberation
• A Natural Sounding Reverberation
• Flanging
• Equalizer

5
Delay

• plays audio after the delay time
• from several milliseconds to several seconds
• Analog delay
• Digital delay
• is used by electric guitarists

6
Multiple echo

• Reflection of sound
• infinite number of echoes
• in music may produce unpleasant effect

7
Reverbration

• result of the many reflections of a sound
• sound source stops but the reflections continue
• number of systems developed to simulate
  reverberation
• simple DSPs use multiple feedback delay circuits
  

8
Impulse response of a room
9
Flanging

• "whooshing" sound
• created by mixing a signal with a slightly
  delayed copy of itself
• considered a particular type of phasing effect

10
Equalizer

• allows the user to magnify or dampen any
  frequencies
• Many equalizers change up to 20 different
  frequency bands

11
Our project

• various effects on pre-recorded sound
• Delay
• Multiple Echo
• All pass Reverberation
• A Natural Sounding Reverberation
• audio file manipulated in visual dsp
• Output produced on sound card

12
Background techniques

• musicians have been using different techniques
• Some of these were found by accident
• effects have not changed much in the past few
  years
• from analog signal processing towards digital
  signal processing
• very precise and easily reproduced effects

13
Applications

• In movies and theaters
• To make voice listened better in different
  environments
• in a recording studio
• gives you greater choice of sounds
• better control over different devices used
• For improving the quality of music

14
Methodology

• Delay

15
Delay (contd.)

• Open a file in read mode
• int R5000
• for(i0iltRi)
• yi xi
• for(jRjltxlenj)
• yj xjxj-R

16
Methodology (contd.)

• Multiple Echo
• H(Z)   Z-R / (1 - alpha ( Z-R))

17
Multiple echo (contd.)

• int R5000
• int aa 0.5
• for(i0iltRi)
• yi xi
• for(jRjltxlenj)
• yj xj(aaxj-R)

18
Methodology (contd.)

• All pass Reverberation

19
Methodology (contd.)

• A Natural Sounding Reverberation
• Schroeder's Reverberator

20
Results

• input

21
Results (contd.)

• output

22
Conclusion

• Different sort of effects and filtering
  techniques
• Sound effects are done digitally allowing for a
  wider variety of manipulation
• By the application of DSP, sound quality can be
  improved

23
The End