In a book "Communication Systems" by Simon Haykin, we get this passage on signal phase distortion (see Pg. 100).
In the latter method, it is inevitable that there would be some phase error in the local oscillator output with respect to the carrier wave used to generate the incoming SSB modulated wave. The effect of this phase error is to introduce a phase distortion in the demodulated signal, where each frequency component of the original message signal under-goes a constant phase shift. This phase distortion is tolerable in voice communications, because the human ear is relatively insensitive to phase distortion.In particular, the presence of phase distortion gives rise to a Donald Duck voice effect. In the transmission of music and video signals, on the other hand, the presence of this form of waveform distortion is utterly unacceptable.Well, now at least you know how you can get a Donald Duck voice without any kind of talent or training. :)