Phonetics (from the Greek φωνή (phonê) "sound" or "voice") is the study of the physical sounds of human speech. It is concerned with the physical properties of speech sounds (phones), and the processes of their physiological production, auditory reception, and neurophysiological perception. Phonetics was studied as early as 2,500 years ago in ancient India, with account of the place and manner of articulation of consonants in his 5th century BC treatise on Sanskrit.