Panning Sounds for Speakers and Headphones

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, noting how that's often done wrongly and the sad 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 presents concise 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. It delves into 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. It also explains the relationship between constant-power panning and ambient cross-fading techniques.

Weather sample crossfading
The principle of constant-power panning applies equally to cross-fades, as in this example of adaptive weather ambience created by Pete Goodwin

This chapter sets up the next, which explains Ambisonic panning for any symmetrical array of speakers in 2D or 3D.

Further reading

Ambisonic Surround-Sound Principles and Practice - next chapter abstract.
Interactive Audio Codecs - previous chapter abstract.
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Copyright © 2019 Simon N Goodwin     [';']