David S. McGrath

Methods and apparatus for processing spatialized audio

A method for distribution multiple users of a soundfield having positional spatial components is disclosed including inputting a soundfield signal having the desired positional spatial components in a standard reference frame; applying at least one head related transfer function to each spatial component to produce a series of transmission signals; transmitting the transmission signals to the multiple users; for each of the multiple users, determining a current orientation of a current user and producing a current orientation signal indicative thereof; utilising the current orientation signal to mix the transmission signals so as to produce sound emission source output signals for playback to the user. The soundfield signal can comprise a B-format signal which is suitably processed.

Time processed head related transfer functions in a headphone spatialization system

An apparatus for implementing a Head Related Transfer Function on an input audio signal in a headtracked listening environment comprising: a series of principle component filters attached to the input audio signal and each outputting a predetermined simulated sound arrival; a series of delay elements each attached to a corresponding one of the principle component filters and delaying the output of the filter by a variable amount depending on a delay input so as to produce a filter delay output; a summation means interconnected to the series of delay elements and summing the filter delay outputs to produce an audio speaker output signal; headtrack parameter mapping unit having a current orientation signal input and interconnected to each of the series of delay elements so as to provided the delay inputs.

Criteria for accurate acoustic emulation

The technique of auralization was pioneered by acoustics researchers in the field of concert hall simulation, where an accurate rendering of the acoustics implied that all characteristics of an acoustic space were reproduced, wherever possible. As the convolution technology is pushed into more cost‐effective implementations, the broader potential for this technology is being realized. Now the criteria for acoustic emulation must be reevaluated to take into account a number of new factors. This paper explores many relevant criteria for repeatability testing and characterizing the performance of equipment in the presence of realistic three‐dimensional noise fields and complex acoustic environments. Such an acoustic system can be accurately emulated using real‐time simulation hardware, if a complete characterization of the system can be obtained. This paper discusses methods that are appropriate for the implementation of accurate acoustic emulation, with the emphasis on real world problems and solutions. It ...