The impact of system latency on dynamic performance in virtual acoustic environments

Abstract

Engineering constraints that may be encountered when implementing interactive virtual acoustic displays are examined. In particular, system parameters such as the update rate and total system latency are defined and the impact they may have on perception is discussed. For example, examination of the head motions that listeners used to aid localization in a previous study suggests that some head motions may be as fast as about 175°/s for short time periods. Analysis of latencies in virtual acoustic environments (VAEs) suggests that: (1) commonly specified parameters such as the audio update rate determine only the best-case latency possible in a VAE, (2) total system latency and individual latencies of system components, including head-trackers, are frequently not measured by VAE developers, and (3) typical system latencies may result in undersampling of relative listener-source motion of 175°/s as well as positional instability in the simulated source. To clearly specify the dynamic performance of a particular VAE, users and developers need to make measurements to average system latency, update rate, and their variability using standardized rendering scenarios. Psychoacoustic parameters such as the minimum audible movement angle can then be used as target guidelines to assess whether a given system meets perceptual requirements.