Perceptual weighting of individual and concurrent cues for sentence intelligibility: Frequency, envelope, and fine structure

Abstract

The speech signal may be divided into frequency bands, each containing temporal properties of the envelope and fine structure. For maximal speech understanding, listeners must allocate their perceptual resources to the most informative acoustic properties. Understanding this perceptual weighting is essential for the design of assistive listening devices that need to preserve these important speech cues. This study measured the perceptual weighting of young normal-hearing listeners for the envelope and fine structure in each of three frequency bands for sentence materials. Perceptual weights were obtained under two listening contexts: (1) when each acoustic property was presented individually and (2) when multiple acoustic properties were available concurrently. The processing method was designed to vary the availability of each acoustic property independently by adding noise at different levels. Perceptual weights were determined by correlating a listener's performance with the availability of each acoustic property on a trial-by-trial basis. Results demonstrated that weights were (1) equal when acoustic properties were presented individually and (2) biased toward envelope and mid-frequency information when multiple properties were available. Results suggest a complex interaction between the available acoustic properties and the listening context in determining how best to allocate perceptual resources when listening to speech in noise.

Binaural Gain Modulation of Spectrotemporal Tuning in the Interaural Level Difference-Coding Pathway

“…These data support previous work in the lateral geniculate nucleus (Butts et al, 2011) as well as previous reports from the auditory cortex (Wehr and Zador, 2003;Wu et al, 2008) and somatosensory cortex (Gabernet et al, 2005;Wilent and Contreras, 2005) that suggest that delayed inhibition can enhance stimulus selectivity, spike-timing precision, and reliability. Our work supports the notion that this is a general mechanism in sensory coding, across stages and species.…”

“…Our work demonstrates that delayed, spectrotemporally tuned inhibition enhances envelope locking by gain control, leading to the suppression of lowprobability responses. This is important to the discrimination of complex stimuli, such as speech, whose intelligibility has been shown to rely heavily on envelope information (Shannon et al, 1995;Smith et al, 2002;Fogerty, 2011).…”

“…Encoding information about spectrotemporal features is essential for discriminating between sounds, such as in speech and species-specific vocalizations (Shannon et al, 1995;Smith et al, 2002;Woolley et al, 2005;Suta et al, 2007;Nelson and Takahashi, 2010;Schneider and Woolley, 2010;Fogerty, 2011;Wang et al, 2011). In the auditory pathway, the timing of the spikes carries spectrotemporal information (Hermes et al, 1981;Theunissen et al, 2000;Escabí and Read, 2003;Linden et al, 2003;Joris et al, 2004;Christianson and Peña, 2007;Steinberg and Peña, 2011).…”

A correlational method to concurrently measure envelope and temporal fine structure weights: Effects of age, cochlear pathology, and spectral shaping

“…Signal processing of the experimental sentences was conducted following the procedures described by Fogerty (2011a) and is detailed below. No sentences were repeated from Experiment 1 A.…”

“…Weighting functions obtained indicate the "importance" listeners place on suprathreshold temporal information across the broadband speech signal. Fogerty (2011a) recently demonstrated that this method is able to present the full power spectrum of speech, while using noise to independently mask E and TFS components in different frequency bands. The current study applies this method to investigating perceptual weighting strategies a) Portions of the data were presented at the 162nd Meeting of the Acoustical Society of America [J.…”