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

Abstract

The speech signal may be divided into spectral frequency-bands, each band containing temporal properties of the envelope and fine structure. This study measured the perceptual weights for the envelope and fine structure in each of three frequency bands for sentence materials in young normalhearing listeners, older normal-hearing listeners, aided older hearing-impaired listeners, and spectrally matched young normal-hearing listeners. The availability of each acoustic property was independently varied through noisy signal extraction. Thus, the full speech stimulus was presented with noise used to mask six different auditory channels. Perceptual weights were determined by correlating a listener's performance with the signal-to-noise ratio of each acoustic property on a trial-by-trial basis. Results demonstrate that temporal fine structure perceptual weights remain stable across the four listener groups. However, a different weighting typography was observed across the listener groups for envelope cues. Results suggest that spectral shaping used to preserve the audibility of the speech stimulus may alter the allocation of perceptual resources. The relative perceptual weighting of envelope cues may also change with age. Concurrent testing of sentences repeated once on a previous day demonstrated that weighting strategies for all listener groups can change, suggesting an initial stabilization period or susceptibility to auditory training.

Sentence intelligibility during segmental interruption and masking by speech-modulated noise: Effects of age and hearing loss

“…The effect of this spectral shaping (increasing the sensation level) was explored in the current study by including a group of younger normal hearing adults who listened to speech that was spectrally shaped according to the mean audiogram of the older hearing-impaired listeners. While generally successful at ensuring audibility (Humes, 2013), spectral shaping can alter how listeners perceptually weight the temporal envelope in different spectral regions (Fogerty and Humes, 2012b). Spectral shaping amplifies the high frequencies more than the low frequencies for the typical older adult with high frequency hearing loss.…”

“…Amplitude modulated signals from a competing talker may specifically interfere with a listener's ability to process the envelope cues of the target sentence, particularly for older adults who have more difficulty in temporally complex listening environments. The spectral shaping that is modeled after hearing aid algorithms to ensure sufficient audibility of the speech signal also interacts with the amplitude modulations of the speech signal and may have significant implications for processing envelope cues that are available for listeners (Fogerty and Humes, 2012b). This is in addition to other changes in amplitude modulation that might result from hearing aid processing, such as amplitude compression (e.g., Jenstad and Souza, 2007;Sabin et al, 2013).…”

Infants’ and Adults’ Use of Temporal Cues in Consonant Discrimination

“…Furthermore, when speech sounds are distorted, masked, spectrally smeared or temporally interrupted, fast AM and FM cues assume greater importance ( e.g. , Nelson et al ., 2003; Gilbert et al ., 2007; Stone et al , 2008; Ardoint & Lorenzi, 2010; Hopkins et al ., 2010), and the perceptual weighting of AM and FM cues appears to change with listening conditions ( e.g., Fogerty, 2011; Fogerty & Humes, 2012). Thus, adults appear to require fast AM cues and FM cues to identify speech under some listening conditions.…”

Perception of Pure Tones and Iterated Rippled Noise for Normal Hearing and Cochlear Implant Users

“…TFS and Envelope. Speech is a temporally complex signal, containing both slow amplitude modulations of the temporal envelope and fast frequency oscillations of the temporal fine structure (TFS) within each frequency band (Fogerty & Humes, 2012). The envelope information that is transmitted primarily by most current CI processing strategies is sufficient for understanding speech in quiet conditions (Wilson et al, 1991;Wilson, Lawson, Zerbi, Finley, & Wolford, 1995).…”