.ac3

AC3, an audio file format, is associated with the similarly named AC3 Audio Files that has been developed by the Dolby Laboratories. AC3 is a 6-channel audio format that is being used during DVD viewing. Five of the six channels are being used in speakers in the 20 to 20.000 Hz range and the sixth is for low-frequency (20 to 120 Hz) sub-woofers.