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.

Purpose In this study, the authors investigated the effects of age on the use of fundamental frequency differences (ΔF0) in the perception of competing synthesized vowels in simulations of electroacoustic and cochlear-implant hearing. Method Twelve younger listeners with normal hearing and 13 older listeners with (near) normal hearing were evaluated in their use of ΔF0 in the perception of competing synthesized vowels for 3 conditions: unprocessed synthesized vowels (UNP), envelope-vocoded synthesized vowels that simulated a cochlear implant (VOC), and synthesized vowels processed to simulate electroacoustic stimulation (EAS) hearing. Tasks included (a) multiplicity, which required listeners to identify whether a stimulus contained 1 or 2 sounds and (b) double-vowel identification, which required listeners to attach phonemic labels to the competing synthesized vowels. Results Multiplicity perception was facilitated by ΔF0 in UNP and EAS but not in VOC, with no age-related deficits evident. Double-vowel identification was facilitated by ΔF0, with ΔF0 benefit largest in UNP, reduced in EAS, and absent in VOC. Age adversely affected overall identification and ΔF0 benefit on the double-vowel task. Conclusions Some but not all older listeners derived ΔF0 benefit in EAS hearing. This variability may partly be due to how listeners are able to draw on higher-level processing resources in extracting and integrating cues in EAS hearing.

The results presented in this article represent a first step in applying the HASPI and HASQI metrics to commercial hearing aids. Modern hearing aids often use several different processing strategies operating simultaneously. The proposed metrics provide a way to predict the total effect of this processing, including algorithm interactions that may be missed by conventional measurement procedures. The measurements in this article show significant differences between manufacturers, processing settings, and adjustment for different hearing losses. No significant differences were found between basic and premium hearing aid models. Further research will be needed to determine the clinical relevance of these measurements and to provide target values appropriate for successful fittings.

The spectral (frequency) and amplitude cues in speech change rapidly over time. Study of the neural encoding of these dynamic features may help to improve diagnosis and treatment of speechperception difficulties. This study uses tone glides as a simple approximation of dynamic speech sounds to better our understanding of the underlying neural representation of speech. The frequency following response (FFR) was recorded from 10 young normal-hearing adults using six signals varying in glide direction (rising and falling) and extent of frequency change ( 1 3 , 2 3 , and 1 octave). In addition, the FFR was simultaneously recorded using two different electrode montages (vertical and horizontal). These factors were analyzed across three time windows using a measure of response strength (signal-to-noise ratio) and a measure of temporal coherence (stimulus-toresponse correlation coefficient). Results demonstrated effects of extent, montage, and a montageby-window interaction. SNR and stimulus-to-response correlation measures differed in their sensitivity to these factors. These results suggest that the FFR reflects dynamic acoustic characteristics of simple tonal stimuli very well. Additional research is needed to determine how neural encoding may differ for more natural dynamic speech signals and populations with impaired auditory processing.