Currently, supported audio formats are .wav for sound effect (sampling audio) and .mp3 or .ogg for song (streaming audio).
Just set Importer name to AudioImporter and Processor name to SoundEffectProcessor, like below.
<Item Include="\Audio\Electrical-Tone.wav">
<Name>Electrical-Tone</Name>
<BuildAction>Compile</BuildAction>
<Importer Name="AudioImporter" />
<Processor Name="SoundEffectProcessor"/>
</Item>
Just set Importer name to AudioImporter and Processor name to SongProcessor, like below.
<Item Include="\Audio\Srengenge.mp3">
<Name>Srengenge</Name>
<BuildAction>Compile</BuildAction>
<Importer Name="AudioImporter" />
<Processor Name="SongProcessor"/>
</Item>