Conclusion and references:
Three methods for pitch determination, autocorrelation method, cepstrum method and LPC method were examined. The first two methods obtained the similar pitch frequency, whereas, the LPC method obtained a different pitch frequency. The LPC method would be used to detect not only pitch but also formants.
 http://www.google.co.in/url?sa=t&source=web&cd=4&ved=0CDMQFjAD&url=http%3A%2F%2Fieeex plore.ieee.org%2Fiel4%2F89%2F8806%2F00388147.pdf%3Farnumber%3D388147&ei=OEOrTZepHdRrQfLiJmnCA&usg=AFQjCNHiG6Ph4jawhQrwREfclzrmCEvBrQ