BMPCC Wiki

The BMPCC has a built-in stereo microphone and a 3.5mm stereo mini-plug input for external audio. The internal microphones are considered unusable for audio recording, unless it's simply as a reference sound for syncing an external sound source.

The frequency range is surprisingly bad and some internal noise is introduced by the camera itself. Example 01

On the other hand, the audio-input expects a +4dBm professional (but unbalanced) line level signal, while most consumer and semi-pro equipment are outputting -10dBm levels. For that reason, the audio levels often have to be raised to reflect that difference, when dealing with -10dBm sound, a rough estimate is setting the input level sensitivity to MIC and the input volume to 50%.

Since the most recent firmware still has no audio meters, it is difficult to check the volume on set. One way is connecting a field monitor or EVF that displays audio levels or recording through an external field mixer.

There is an audio FAQ covering most common questions on Audio with the BMPCC at the Blackmagic Forum.  Audio FAQ @ BM Forum