1680s, "phonetics, the doctrine or science of sound," especially of the human voice, from Greek phōnē "sound, voice" (from PIE root *bha- (2) "to speak, tell, say") + -ics.
As the name of a method of teaching reading by associating letters or groups of letters with particular sounds in an alphabetic writing system, especially as correlations between sound and symbol, it is attested by 1901 and became prominent in that sense after 1950, though the systematic method itself dates from the 1830s.