Hello,
Roughly speaking, a speech signal can be classified as voiced or unvoiced. Voiced
sounds are generated when the vocal cords vibrate in such a way that the flow of air from the lungs is interrupted periodically, creating a sequence of pulses to excite the vocal tract.eg, when we utter vowels like 'a', 'e', etc.
In timedomain, voiced sound is characterized by strong periodicity present in the signal,with the fundamental frequency referred to as the pitch frequency, or simply pitch.For men, pitch ranges from 50 to 250 Hz, while for women the range usually falls somewhere in the interval of 120 to 500 Hz.Pitch
frequency is directly related to the speaker and sets the unique characteristic of a
person.Pitch period can be estimated from different techniques and one simple method is autocorrelation method where the periodicity in the signal can be measured.
Hope this helped you.