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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. 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

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  1. Effect of the Phase on Speech and Musical signals using DWT By: Hafiz, Malik ECE418,DSPII Spring,02

  2. Talk outline • Introduction • Block Diagram • Results • Applications • conclusion

  3. Introduction • What is Phase and phase-shift? • Effect of the phase on the signals? • How to play with phase?

  4. 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.

  5. 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.

  6. All-Pass Systems and their applications • What are All-Pass Filters ? • Can I use All-Pass Filters to shift the Phase….??? • Yes! Why not…

  7. Overview of All-pass systems • Pole-Zero • Magnitude • Phase

  8. How to play with phase??? • Using Transformed domain i.e. FT,CT, etc • Using all-Pass filters

  9. Input Audio wavelet Analysis Filter bank All-Pass system wavelet synthesis Filter bank Output Audio Block Diagram

  10. 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

  11. Result: Using All-Pass filters & DWT cDs & cA Superimposed coef.

  12. Result2: Using All-Pass filters & DWT D1 only A8 & D8 only

  13. Results…. original D8 & A8 D1 only With all Musical signal

  14. Results… original A8 & D8 D1 only With all Audio signal

  15. Magnitude Response due to phase-shift original D8 only A8 & D8 With all

  16. Applications • Data Hiding • Watermarking • Captioning • Hiding signature to the songs • Hiding signature to the images

  17. 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.

  18. Thanks!!!! Hafiz, Malik

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