Selecting the optimal audio bit rate – the rate at which the audio data is transferred – directly determines the overall size of the audio object. The higher the bit rate, the larger the file is that needs to be transferred online. Additionally, long audio objects recorded with unnecessarily high bit rates can lead to using up your bandwidth and the bandwidth of your users.
Music perfectionists demand the highest bit rates for music; however, for audio objects containing mostly voice and talking, lower bit rates – 64kbps to 192kbps can be used (96kbps in mono recording is recommended). If file size is an issue and the object contains only voice narration, 64kpbs mono is suggested.
For more complex audio objects – often with sound as a background to voice sections – you might want to increase to 128kbps to provide extra clarity. Always choose a constant bit rate; variable bit rates can cause problems and are not recommended. Replay your audio objects to make sure the quality is achieved while maintaining manageable file sizes.