How is billing calculated for multiple channels in an audio stream?

Speaker separated channel audio file is billed according to the number of channels present in the audio files. The duration for billing will be calculated according to the below formula:

totalDuration = duration_of_the_audio_file * total_number_of_channels

For example, if you send a 120-second file with 3 speaker separated channels the total duration for billing would be 360 seconds or 6 minutes.