Function XPLMSetAudioCone 

pub unsafe extern "C" fn XPLMSetAudioCone(
    fmod_channel: *mut FMOD_CHANNEL,
    inside_angle: f32,
    outside_angle: f32,
    outside_volume: f32,
    orientation: *mut FMOD_VECTOR,
) -> FMOD_RESULT

XPLMSetAudioCone

Set a directional cone for an active FMOD channel. The orientation vector is in local coordinates. This will set the sound to 3D if it is not already.