A: A directivity file describes how power is distributed around a source for different frequency bands. Loudspeakers typically are highly directive at high frequencies, so that most of the sound power is emitted in front of it. The standard format for making directivity files is called Common Loudspeaker Format (CLF) and was developed by the CLF-group (www.clfgroup.org). Such files have an extension of .CF1 or .CF2, for CLF version 1 and 2, respectively. The .CF2 format is the newest one including phase information.