ABSTRACT
Locating threats you can’t see is often a matter of (virtual) life and death to interactive players. This chapter explains psychoacoustically correct ways to assign constant-power proportions of a mix between stereo speakers and headphones, with C++ source, how that’s often done wrongly and the consequences.
From a simple fix for “hundred-foot-wide car” syndrome to advanced binaural techniques which use Ear- and Head-Related Transfer Functions (ERTF/HRTF) and Head-Related Impulse Responses (HRIR), it contrasts six downloadable sets of binaural data for 3D, shows the impossibility of creating a “universal” HRTF and introduces the AES69 standard for individually personalised HRTF and 3D room response data, based on SOFA, the Spatially Oriented Format for Acoustics. It includes concise scalar convolution code in C++ and SIMD techniques to speed it up.
The chapter explains the power and limitations of cross-talk cancellation (CTC) in delivering surround sound from stereo dipole speakers, stereo and quadraphonic history, middleware risks, dynamic re-configuration and why 5.1 channel ITU cinema surround layout is inappropriate for games and domestic installations and sensibly ignored by Apple, Creative Labs, Microsoft and Sony.
This chapter sets up the next, which explains Ambisonic panning for any symmetrical array of speakers in 2D or 3D.
