The format a sound’s data is stored in, and subsequently what format is retrieved by lock(), will depend on the FMOD_MODE used to create the sound - either PCM data, if the mode decompresses the source audio, or compressed data if a mode like FMOD_CREATECOMPRESSEDSAMPLE is used.
A sound’s bit rate/sample rate will depend on the asset used. You can get format info on the sound with Sound::getFormat. However, upon data from the sound being played into the FMOD system, it will be resampled to match the sample rate of the FMOD system’s mixer, which by default is 48kHz, or 24kHz on lower-spec platforms like mobile.