Effect of the phase on speech and musical signals using dwt
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Effect of the Phase on Speech and Musical signals using DWT. By: Hafiz, Malik ECE418,DSPII Spring,02. Talk outline. Introduction Block Diagram Results Applications conclusion. Introduction. What is Phase and phase-shift? Effect of the phase on the signals? How to play with phase?.

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Effect of the phase on speech and musical signals using dwt

Effect of the Phase on Speech and Musical signals using DWT

By:

Hafiz, Malik

ECE418,DSPII

Spring,02


Talk outline
Talk outline

  • Introduction

  • Block Diagram

  • Results

  • Applications

  • conclusion


Introduction
Introduction

  • What is Phase and phase-shift?

  • Effect of the phase on the signals?

  • How to play with phase?


What is phase phase shift
What is phase & phase shift?

  • Start/peak location of a signal with certain reference.

  • Phase shift is nothing more than a temporal shift.

    The red curve is the original signal, the blue one is the signal that has been phase-shifted; in black, the result of adding these two.


Effect of the phase shift on the mixed signals
Effect of the phase-shift on the mixed signals

Xresult = Xorignal+ Xshift

  • when summing two identical signals, one phase-shifted a few milliseconds vs. the other, some frequencies will be amplified, some others will be attenuated.

  • The higher in the frequency spectrum, the more noticeable the changes in the resulting sound.


All pass systems and their applications
All-Pass Systems and their applications

  • What are All-Pass Filters ?

  • Can I use All-Pass Filters to shift the Phase….???

  • Yes! Why not…


Overview of all pass systems
Overview of All-pass systems

  • Pole-Zero

  • Magnitude

  • Phase


How to play with phase
How to play with phase???

  • Using Transformed domain i.e. FT,CT, etc

  • Using all-Pass filters


Block diagram

Input

Audio

wavelet

Analysis

Filter

bank

All-Pass

system

wavelet

synthesis

Filter

bank

Output

Audio

Block Diagram


Wavelet analysis synthesis filter banks with phase shift system

Input audio

APF

Data hiding

output audio with embedded data

HPF

HPF

LPF

APF

LPF

LPF

APF

LPF

Wavelet Analysis/Synthesis Filter Banks with phase shift system


Result using all pass filters dwt
Result: Using All-Pass filters & DWT

cDs & cA

Superimposed coef.


Result2 using all pass filters dwt
Result2: Using All-Pass filters & DWT

D1 only

A8 & D8 only


Results
Results….

original

D8 & A8

D1 only

With all

Musical signal


Results1
Results…

original

A8 & D8

D1 only

With all

Audio signal


Magnitude response due to phase shift
Magnitude Response due to phase-shift

original

D8 only

A8 & D8

With all


Applications
Applications

  • Data Hiding

    • Watermarking

    • Captioning

  • Hiding signature to the songs

  • Hiding signature to the images


  • Future direction
    Future Direction

    • More sophisticated system for data hiding can be developed with out deteriorating the quality of the audio by exploiting the fact that human perception is bit insensitive to certain bands of frequency.

    • This thing can be done by frequency selective phase-shifting.

    • This method i.e. frequency selective phase-shifting will also work for images as well as video.


    Thanks

    Thanks!!!!

    Hafiz, Malik


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