Effects of Age on F0 Discrimination and Intonation Perception in Simulated Electric and Electroacoustic Hearing

Abstract

Objectives Recent research suggests that older listeners may have difficulty processing information related to the fundamental frequency (F0) of voiced speech. In this study, the focus was on the mechanisms that may underlie this reduced ability. We examined whether increased age resulted in decreased ability to perceive F0 using fine structure cues provided by the harmonic structure of voiced speech sounds and/or cues provided by high-rate envelope fluctuations (periodicity). Design Younger listeners with normal hearing and older listeners with normal to near-normal hearing completed two tasks of F0 perception. In the first task (steady-state F0), the fundamental frequency difference limen (F0DL) was measured adaptively for synthetic vowel stimuli. In the second task (time-varying F0), listeners relied on variations in F0 to judge intonation of synthetic diphthongs. For both tasks, three processing conditions were created: 8-channel vocoding which preserved periodicity cues to F0; a simulated electroacoustic stimulation condition, which consisted of high-frequency vocoder processing combined with a low-pass filtered portion, and offered both periodicity and fine-structure cues to F0; and an unprocessed condition. Results F0 difference limens for steady-state vowel sounds and the ability to discern rising and falling intonations were significantly worse in the older subjects compared to the younger subjects. For both older and younger listeners scores were lowest for the vocoded condition, and there was no difference in scores between the unprocessed and electroacoustic simulation conditions. Conclusions Older listeners had difficulty using periodicity cues to obtain information related to talker fundamental frequency. However, performance was improved by combining periodicity cues with (low-frequency) acoustic information, and that strategy should be considered in individuals who are appropriate candidates for such processing. For cochlear implant candidates, that effect might be achieved by partial electrode insertion providing acoustic stimulation in the low frequencies; or by the combination of a traditional implant in one ear and a hearing aid in the opposite ear.

The Effect of Dynamic Pitch on Speech Recognition in Temporally Modulated Noise

“…Indeed, our previous studies have demonstrated a large amount of individual variability in dynamic-pitch perception among older listeners with good hearing (Shen, Wright, & Souza, 2016;Souza, Arehart, Miller, & Muralimanohar, 2011). Although this variability may largely stem from suprathreshold and perceptual deficits of some older individuals with near-normal thresholds, we expect any deficits to be more prevalent in listeners with mild-moderate hearing loss (Buss, Hall, & Grose, 2004;Hopkins & Moore, 2011;.…”

Assessment of auditory processing disorder in children using an adaptive filtered speech test

“…All participants with UCAST-FW scores over 900 Hz failed the RGDT binaurally. Speech recognition involves the use of multiple cues, both spectral and temporal, in the speech signal (Shannon et al, 1995;Xu et al, 2005;Souza et al, 2011). Low pass filtering a speech signal removes high frequency spectral information, which negatively impacts on speech understanding (Bornstein et al, 1994;Ardoint & Lorenzi, 2010) .…”

The effect of spectral smearing on the identification of pureF0intonation contours in vocoder simulations of cochlear implants

“…Our first hypothesis was that NH listeners would have more difficulty in discriminating melodies in the vocoded than in the unprocessed condition. Our second hypothesis was that a steeper slope (40 dB/octave) should induce better recognition than a shallower slope owing to the smaller amount of channel interaction (Litvak et al, 2007;Shannon et al, 1995;Souza et al, 2011). If participants would be unable to perform the task with these settings, this would imply that more extreme filter slopes, possibly a higher number of electrodes and/or additional (non-pitch related) cues were required for the identification of intonation.…”

“…The resulting set of re-synthesized stimuli comprised 18 stimuli. Importantly, the use of naturally produced re-synthesized stimuli, in comparison with previous studies where synthetic phonemes were used (Litvak et al, 2007;Shannon et al, 1995;Souza et al, 2011), ensured that the stimuli were relatively realistic. For the 18 stimuli, noise-band vocoder processing was implemented using Matlab, following the same algorithm as described in Litvak et al (2007).…”

“…However, the average performance of implant users in the perception of speech intonation remains much poorer than that of normal-hearing (NH) listeners (Chatterjee and Peng, 2008;Peng et al, 2009;Souza et al, 2011). Intonation is a type of prosody.…”