08-17-2017, 12:40 AM
VOICE MORPHIING
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What is voice morphing?
The smooth transition of one speech signal to another, keeping the shared characteristics of starting & ending signals.
It is a technique for modifying a (source) speaker's speech to sound as if it were spoken by a different (target) speaker.
In Simpler terms it is being able to change the speech of one speaker to that of another speaker.
Applications for Voice Morphing range from recreational ones to security ones.
Morphing process
1.Two signals with diff. pitches produce two separate sounds.
2.The pitch information of each sound is compared to provide the best match between the two signal s pitches.
3. For this the signals are stretched and compressed so that important sections of each signal match.
4. The interpolation of the two sounds can then be performed which creates the intermediate sound.
5. The final stage is then to convert the frames back into a normal waveform.
Terms used in morphing
DFT:- Discrete Fourier Transform is a specific kind of discrete transform, used in Fourier analysis. one function into another, which is called the frequency domain representation of the original function.
Formant:- Formants are the meaningful frequency components of human speech and of singing. It is the spectral peaks of the sound spectrum of the voice.
Cepstrum:- Cepstrum is the result of taking the Fourier transform of the logarithm of the spectrum of a signal.
how to morph voice?
The pitch of a female speaker will be close to twice that of the male speaker. In our example the pitch of the male speaker is 141Hz and that of the female speaker is 210Hz.
We need to effectively change the pitch from that of a male speaker to that of a female speaker. If we reminisce the excitation signal has information about the speaker.
We find the LPC coefficients for the Source and Target Signals and using these coefficients we are going to interpolate between the two Signals.