class B push-pull sound track

class B push-pull sound track

[‚klas ′bē ¦pu̇sh ¦pu̇l ′sau̇n ‚trak]
(engineering acoustics)
Two photographic sound tracks side by side, one of which carries the positive half of the signal only, and the other the negative half; during the inoperative half-cycle, each track transmits little or no light.