Linear predictive coding ( LPC ) was first developed by Fumitada Itakura of Nagoya University and Shuzo Saito of Nippon Telegraph and Telephone ( NTT ) in 1966 , and then further developed by Bishnu S. Atal and Manfred R. Schroeder at Bell Labs during the early-to-mid-1970s , becoming a basis for the first speech synthesizer DSP chips in the late 1970s .