Reduced Semantic Context and Signal-to-Noise Ratio Increase Listening Effort As Measured Using Functional Near-Infrared Spectroscopy.

OBJECTIVES: Understanding speech-in-noise can be highly effortful. Decreasing the signal-to-noise ratio (SNR) of speech increases listening effort, but it is relatively unclear if decreasing the level of semantic context does as well. The current study used functional near-infrared spectroscopy to evaluate two primary hypotheses: (1) listening effort (operationalized as oxygenation of the left lateral PFC) increases as the SNR decreases and (2) listening effort increases as context decreases. DESIGN: Twenty-eight younger adults with normal hearing completed the Revised Speech Perception in Noise Test, in which they listened to sentences and reported the final word. These sentences either had an easy SNR (+4 dB) or a hard SNR (-2 dB), and were either low in semantic context (e.g., "Tom could have thought about the sport") or high in context (e.g., "She had to vacuum the rug"). PFC oxygenation was measured throughout using functional near-infrared spectroscopy. RESULTS: Accuracy on the Revised Speech Perception in Noise Test was worse when the SNR was hard than when it was easy, and worse for sentences low in semantic context than high in context. Similarly, oxygenation across the entire PFC (including the left lateral PFC) was greater when the SNR was hard, and left lateral PFC oxygenation was greater when context was low. CONCLUSIONS: These results suggest that activation of the left lateral PFC (interpreted here as reflecting listening effort) increases to compensate for acoustic and linguistic challenges. This may reflect the increased engagement of domain-general and domain-specific processes subserved by the dorsolateral prefrontal cortex (e.g., cognitive control) and inferior frontal gyrus (e.g., predicting the sensory consequences of articulatory gestures), respectively.

Descriptions of Hearing Aids Influence the Experience of Listening to Hearing Aids.

OBJECTIVES: Experiences can be strongly influenced by expectations. In hearing healthcare, previous studies have shown that descriptions of hearing aids or contextual factors during the hearing aid fitting process can change subjective and even objective outcomes with hearing aids via the placebo effect. Personality factors have also been shown to affect susceptibility to placebo effects. The purposes of the present study were to (a) investigate the effects of communicating narratives designed to foster positive, negative, or neutral expectations about hearing aids on short-term patient outcomes, and (b) to determine if the degree to which the narratives affected end-user outcomes could be predicted by personality factors. DESIGN: Nineteen adults between the ages of 54 and 81 (mean age = 68.5, SD = 8.9) had 3 separate research appointments, each exposing them to a different narrative condition: positive, negative, or neutral. the appointment was designed to look and feel like a "traditional" hearing aid fitting appointment, during which the experimenter introduced (i.e., the narrative condition) and fit a pair of hearing aids, the participant was asked to provide their initial feedback about the hearing aids, and the participant performed speech-in-noise testing. Unbeknownst to the research participant, the hearing aids fitted at all three appointments were the same, and the only difference between the three appointments was the way the hearing aids were described to the participants. RESULTS: The results of this study showed that communication of a positive narrative about hearing aids before a hearing aid fitting led to better speech-in-noise performance on the QuickSIN as compared with performance following the negative or neutral narrative conditions. Also, the positive narrative led to the perception that acclimatization to the hearing aids would occur faster than the negative or neutral narrative conditions. Notably, the effect of communication of a positive narrative was stronger for individuals who scored higher on agreeableness, and susceptibility to positive and negative messaging was stronger for individuals low in neuroticism. CONCLUSIONS: The study suggests that short-term evaluations of hearing aids can be strongly influenced by narratives as provided by the hearing healthcare provider at the time of a hearing aid fitting.

Comparing verbal working memory load in auditory and visual modalities using functional near-infrared spectroscopy.

The verbal identity n-back task is commonly used to assess verbal working memory (VWM) capacity. Only three studies have compared brain activation during the n-back when using auditory and visual stimuli. The earliest study, a positron emission tomography study of the 3-back, found no differences in VWM-related brain activation between n-back modalities. In contrast, two subsequent functional magnetic resonance imaging (fMRI) studies of the 2-back found that auditory VWM was associated with greater left dorsolateral prefrontal cortex (DL-PFC) activation than visual VWM, perhaps suggesting that auditory VWM requires more cognitive effort than its visual counterpart. The current study aimed to assess whether DL-PFC activation (i.e., cognitive effort) differs by VWM modality. To do this, 16 younger adults completed an auditory and visual n-back, both at four levels of VWM load. Concurrently, activation of the PFC was measured using functional near-infrared spectroscopy (fNIRS), a silent neuroimaging method. We found that DL-PFC activation increased with VWM load, but it was not affected by VWM modality or the interaction between load and modality. This supports the view that both VWM modalities require similar cognitive effort, and perhaps that previous fMRI results were an artefact of scanner noise. We also found that, across conditions, DL-PFC activation was positively correlated with reaction time. This may further support DL-PFC activation as an index of cognitive effort, and fNIRS as a method to measure it.

Development of the Canadian Digit Triplet Test in English and French.

The Canadian Digit Triplet Test was developed in English and French, the official languages of Canada. Four versions were developed on a common software platform using recordings produced by two fluent bilinguals, one male and one female, following procedures recommended by international guidelines. Phase I of test development focused on homogenizing digit recognition across tokens and positions within the triplets for young adults with normal hearing (n = 48). In phase II, normative data were collected for young adults with normal hearing (n = 64). Statistical properties were found to be uniform across test versions and comparable to digit triplet tests in other languages.

Functional Near-Infrared Spectroscopy as a Measure of Listening Effort in Older Adults Who Use Hearing Aids.

Listening effort may be reduced when hearing aids improve access to the acoustic signal. However, this possibility is difficult to evaluate because many neuroimaging methods used to measure listening effort are incompatible with hearing aid use. Functional near-infrared spectroscopy (fNIRS), which can be used to measure the concentration of oxygen in the prefrontal cortex (PFC), appears to be well-suited to this application. The first aim of this study was to establish whether fNIRS could measure cognitive effort during listening in older adults who use hearing aids. The second aim was to use fNIRS to determine if listening effort, a form of cognitive effort, differed depending on whether or not hearing aids were used when listening to sound presented at 35 dB SL (flat gain). Sixteen older adults who were experienced hearing aid users completed an auditory n-back task and a visual n-back task; both tasks were completed with and without hearing aids. We found that PFC oxygenation increased with n-back working memory demand in both modalities, supporting the use of fNIRS to measure cognitive effort during listening in this population. PFC oxygenation was weakly and nonsignificantly correlated with self-reported listening effort and reaction time, respectively, suggesting that PFC oxygenation assesses a dimension of listening effort that differs from these other measures. Furthermore, the extent to which hearing aids reduced PFC oxygenation in the left lateral PFC was positively correlated with age and pure-tone average thresholds. The implications of these findings as well as future directions are discussed.

Hearing, Emotion, Amplification, Research, and Training Workshop: Current Understanding of Hearing Loss and Emotion Perception and Priorities for Future Research.

The question of how hearing loss and hearing rehabilitation affect patients' momentary emotional experiences is one that has received little attention but has considerable potential to affect patients' psychosocial function. This article is a product from the Hearing, Emotion, Amplification, Research, and Training workshop, which was convened to develop a consensus document describing research on emotion perception relevant for hearing research. This article outlines conceptual frameworks for the investigation of emotion in hearing research; available subjective, objective, neurophysiologic, and peripheral physiologic data acquisition research methods; the effects of age and hearing loss on emotion perception; potential rehabilitation strategies; priorities for future research; and implications for clinical audiologic rehabilitation. More broadly, this article aims to increase awareness about emotion perception research in audiology and to stimulate additional research on the topic.

Hearing Aids Benefit Recognition of Words in Emotional Speech but Not Emotion Identification.

Vocal emotion perception is an important part of speech communication and social interaction. Although older adults with normal audiograms are known to be less accurate at identifying vocal emotion compared to younger adults, little is known about how older adults with hearing loss perceive vocal emotion or whether hearing aids improve the perception of emotional speech. In the main experiment, older hearing aid users were presented with sentences spoken in seven emotion conditions, with and without their own hearing aids. Listeners reported the words that they heard as well as the emotion portrayed in each sentence. The use of hearing aids improved word-recognition accuracy in quiet from 38.1% (unaided) to 65.1% (aided) but did not significantly change emotion-identification accuracy (36.0% unaided, 41.8% aided). In a follow-up experiment, normal-hearing young listeners were tested on the same stimuli. Normal-hearing younger listeners and older listeners with hearing loss showed similar patterns in how emotion affected word-recognition performance but different patterns in how emotion affected emotion-identification performance. In contrast to the present findings, previous studies did not find age-related differences between younger and older normal-hearing listeners in how emotion affected emotion-identification performance. These findings suggest that there are changes to emotion identification caused by hearing loss that are beyond those that can be attributed to normal aging, and that hearing aids do not compensate for these changes.

Effects of age on speech and voice quality ratings.

The quality of communication may be affected by listeners' perception of talkers' characteristics. This study examined if there were effects of talker and listener age on the perception of speech and voice qualities. Younger and older listeners judged younger and older talkers' gender and age, then rated speech samples on pleasantness, naturalness, clarity, ease of understanding, loudness, and the talker's suitability to be an audiobook reader. For the same talkers, listeners also rated voice samples on pleasantness, roughness, and power. Younger and older talkers were perceived to be similar on most qualities except age. Younger and older listeners rated talkers similarly, except that younger listeners perceived younger voices to be more pleasant and less rough than older voices. For vowel samples, younger listeners were more accurate than older listeners at age estimation, while older listeners were more accurate than younger listeners at gender identification, suggesting that younger and older listeners differ in their evaluation of specific talker characteristics. Thus, the perception of quality was generally more affected by the age of the listener than the age of the talker, and age-related differences between listeners depended on whether voice or speech samples were used and the rating being made.

"Older is always better": Age-related differences in vocabulary scores across 16 years.

Cross-sectional studies of cognitive aging compare age groups at 1 time point. It is unclear from such studies whether age-related cognitive differences remain stable across time. We present a cross-sectional investigation of vocabulary scores of 2,000 younger and older adults collected across 16 years, using the same laboratory and protocol. We found a steady decrease with year of testing and an advantage for older adults. An additive relation between age group and year of testing implied that age-related differences in vocabulary are independent of changes over time, suggesting that younger and older adults are similarly affected by changes in word usage.

The effects of semantic context and the type and amount of acoustic distortion on lexical decision by younger and older adults.

PURPOSE: In this study, the authors investigated how acoustic distortion affected younger and older adults' use of context in a lexical decision task. METHOD: The authors measured lexical decision reaction times (RTs) when intact target words followed acoustically distorted sentence contexts. Contexts were semantically congruent, neutral, or incongruent. Younger adults (n = 216) were tested on three distortion types: low-pass filtering, time compression, and masking by multitalker babble, using two amounts of distortion selected to control for word recognition accuracy. Older adults (n = 108) were tested on two amounts of time compression and one low-pass filtering condition. RESULTS: For both age groups, there was robust facilitation by congruent contexts but minimal inhibition by incongruent contexts. Facilitation decreased as distortion increased. Older listeners had slower RTs than younger listeners, but this difference was smaller in congruent than in neutral or incongruent conditions. After controlling for word recognition accuracy, older listeners' RTs were slower in time-compressed than in low-pass filtering conditions, but younger listeners performed similarly in both conditions. CONCLUSIONS: These RT results highlight the interdependence between bottom-up sensory and top-down semantic processing. Consistent with previous findings based on accuracy measures, compared with younger adults, older adults were disproportionately slowed when speech was time compressed but more facilitated by congruent contexts.

Normative voice data for younger and older adults.

OBJECTIVES: We constructed age- and gender-specific norms for healthy adults on a large number of speech and voice measures using standardized recording procedures. STUDY DESIGN: Participants were 159 younger (mean = 19.1 years, standard deviation [SD] = 1.4) and 133 older (mean = 72.0 years, SD = 4.8) healthy native English male and female speakers who did not currently smoke and had typical hearing for their age group. METHODS: Participants phonated the vowel [a] under various instructions and read an abbreviated version of the Rainbow Passage. Voice measures based on the productions of [a] included fundamental frequency (F(0)), jitter, shimmer, harmonics-to-noise ratio, noise-to-harmonics ratio, maximum phonation time, minimum phonation intensity, maximum pitch, and the Dysphonia Severity Index (DSI). Mean speaking fundamental frequency (SF(0)), SF(0) standard deviation (SF(0)SD), and signal intensity were measured from the reading passage. RESULTS: Noteworthy age-related differences were found for males and females. Older females had a lower F0 and SF(0) and smaller SF(0)SD than younger females, but younger and older males did not differ. Shimmer increased with age for males, but neither jitter nor shimmer increased with age for females, whereas noise measures were similar for both ages. Younger and older males had a similar DSI, whereas older females had a higher DSI than younger females. CONCLUSIONS: This study provides a unique database containing a wide variety of voice measures collected from a large sample of adults in good health using standardized recording procedures. Males and females differed on the type and extent of age-related vocal changes, but overall age-related differences were limited.

Age-related difference in melodic pitch perception is probably mediated by temporal processing: empirical and computational evidence.

OBJECTIVE: This study was designed to examine whether age-related differences in melodic pitch perception may be mediated by temporal processing. Temporal models of pitch suggest that performance will decline as the lowest component of a complex tone increases in frequency, regardless of age. In addition, if there are age-related deficits in temporal processing in older adults, this group may have reduced performance relative to younger adults even in the most favorable conditions. DESIGN: Six younger adults and 10 older adults with clinically normal audiograms up to 8 kHz were tested in a melodic pitch perception task. In each trial, two consecutive four-note melodies were presented to the listener. Melodies were identical with the exception of one note in the second melody that was shifted in pitch. The listener was required to identify which note was shifted. All notes consisted of eight successive harmonic components, with the average lowest component manipulated to be the 4th, 8th, or 12th component of the harmonic series, with lower components being absent. RESULTS: Age-related differences in melodic pitch perception were only apparent when stimulus parameters favored temporal processing of pitch. Furthermore, modeling a loss of periodicity coding yielded an outcome consistent with the observed behavioral results. Although younger adults generally outperformed older adults, about one-quarter of the older adults performed at levels that were equivalent to those of younger adults. The only follow-up tests that were able to differentiate these exceptional older adults were tests that would be sensitive to temporal processing: fundamental frequency difference limens and 500 Hz pure-tone difference limens. In contrast, otoacoustic emissions and high-frequency pure-tone thresholds, which are more commonly associated with spectral processing deficits, were not able to differentiate older exceptional adults from older typical adults. CONCLUSION: Age-related declines in temporal processing contribute to deficits in melodic pitch perception. However, some exceptional older adults with normal audiograms preserve excellent temporal processing and continue to perform at levels that are typical of younger adults.