On the Perception of Transients: Applying Psychophysical Constraints to Improve Audio Analysis and Synthesis

Recent advances in audio representation decompose the signal into a parallel combination of sinusoidal, transient, and noise components and then apply specialized techniques to analyze and synthesize each of these components (Levine and Smith 1999). With respect to time-varying sinusoids and wideband noise, knowledge about auditory perception has been used to optimize the representation. In contrast, relatively less is known about the perception of transients so that the processing of transients is governed primarily by standard signal transform techniques. The present paper presents new psychophysical results on the perception of transients and suggests how these results may be used to improve the analysis and synthesis of transients in the audio signal. Limits on temporal resolution in auditory perception typically range from 25 ms, for the judgment of temporal order, to a lower limit of 1-2 ms for the discrimination of monaural phase (Eddins and Green 1995). For example, Ronken (1970) measured discrimination thresholds for a pair of unequal amplitude clicks and their time-reversed form as a function of the temporal separation between the clicks and the relative amplitude of the clicks. He demonstrated that the threshold amplitude was relatively constant for temporal separations greater than 2 ms, but that the threshold increased when decreasing the temporal separation from 2 to 1 ms. Patterson and Green (1970) studied the discrimination of Huffman sequences, which, for a given duration, share the attribute that they have identical power spectra. They found that discrimination between different Huffman sequences