You can usually recognize a male vs. female voice and adult vs. a child voice. This has a lot to do with the different lengths of vocal cords in males females and children, but it also depends on the thickness of the vocal cords Information about voice fundamental frequencies "Thevoiced speechof a typical adult male will have afundamental frequencyfrom 85 to 180Hz, and that of a typical adult female from 165 to 255Hz The average man's speaking voice, for example, typically has a fundamental frequency between 85 Hz and 155 Hz. A woman's speech range is about 165 Hz to 255 Hz, and a child's voice typically ranges from 250 Hz to 300 Hz and higher.""Baby cries have a fundamental frequency (hereafter referred to as Fo) of around 500 Hz (roughly corresponding to the note B4). Child speech ranges from 250-400 Hz (notes B3to G4, adult females tend to speak at around 200 Hz on average (about G3), and adult males around 125 Hz (or, B2)." "Typical values obtained for F0 are 120 Hz for men and 210 Hz for women" Information about vocal cord lengths "Males and females have different vocal fold sizes. Adult malevoicesare usually lower-pitched due to longer and thicker folds. The male's vocal folds are between 1.75cm and 2.5cm (approx 0.75" to 1.0") in length,[2]while females' vocal folds are between 1.25cm and 1.75cm (approx 0.5" to 0.75") in length. The vocal folds of children are much shorter than those of adult males and females." Here are graphs of the frequency spectrum of a male and female, each saying the vowel "ah" Which graph is typical female and which is typical male? How can you tell?

ref: http://hyperphysics.phy-astr.gsu.edu/hbase/Music/vowel2.html#c1