Audio is only available in live view and recording with the H264 Codec through Internet Explorer only since it uses Active X controls with ipConfigure Embedded Media Player. You will need to manually change the audio codec in the camera to G711 µ-law, Full duplex. Make sure you can hear the audio directly from the camera interface. (Workstation has a sound card with support for full-duplex audio.) Also make sure that the "Audio" checkbox is checked on the camera settings in the ESM admin interface.
The following documentation is available for download below: