Constant rfmod::INIT_HRTF_LOWPASS

pub const INIT_HRTF_LOWPASS: u32 = 16

All platforms - All SOFTWARE (and HARDWARE on 3DS and NGP) with 3D based voices will add a software lowpass filter effect into the DSP chain which causes sounds to sound duller when the sound goes behind the listener. Use Sys::set_advanced_settings to adjust Cutoff frequency.