Cortical-brainstem interplay during speech perception in older adults with and without hearing loss

To provide a critical evaluation of studies examining the contribution of changes in language-specific cognitive abilities to the speech perception difficulties of older adults. A review of the literature on aging and speech perception. The research considered in the present review suggests that age-related changes in absolute sensitivity is the principal factor affecting older listeners' speech perception in quiet. However, under less favorable listening conditions, changes in a number of speech-specific cognitive abilities can also affect spoken language processing in older people. Clinically, these findings suggest that hearing aids, which have been the traditional treatment for improving speech perception in older adults, are likely to offer considerable benefit in quiet listening situations because the amplification they provide can serve to compensate for age-related hearing losses. However, such devices may be less beneficial in more natural environments, (e.g., noisy backgrounds, multiple talkers, reverberant rooms) because they are less effective for improving speech perception difficulties that result from age-related cognitive declines. It is suggested that an integrative approach to designing test batteries that can assess both sensory and cognitive abilities needed for processing spoken language offers the most promising approach for developing therapeutic interventions to improve speech perception in older adults.

The possible role of early-stage phase-locked neural activities in speech-in-noise perception in human adults across age and hearing loss

Objective: People with presbycusis (PC) often report difficulties in speech recognition, especially under noisy listening conditions. Investigating the PC-related changes in central representations of envelope signals and temporal fine structure (TFS) signals of speech sounds is critical for understanding the mechanism underlying the PC-related deficit in speech recognition. Frequency-following responses (FFRs) to speech stimulation can be used to examine the subcortical encoding of both envelope and TFS speech signals. This study compared FFRs to speech signals between listeners with PC and those with clinically normal hearing (NH) under either quiet or noise-masking conditions.Methods: FFRs to a 170-ms speech syllable /da/ were recorded under either a quiet or noise-masking (with a signal-to-noise ratio (SNR) of 8 dB) condition in 14 older adults with PC and 13 age-matched adults with NH. The envelope (FFRENV) and TFS (FFRTFS) components of FFRs were analyzed separately by adding and subtracting the alternative polarity responses, respectively. Speech recognition in noise was evaluated in each participant.Results: In the quiet condition, compared with the NH group, the PC group exhibited smaller F0 and H3 amplitudes and decreased stimulus-response (S-R) correlation for FFRENV but not for FFRTFS. Both the H2 and H3 amplitudes and the S-R correlation of FFRENV significantly decreased in the noise condition compared with the quiet condition in the NH group but not in the PC group. Moreover, the degree of hearing loss was correlated with noise-induced changes in FFRTFS morphology. Furthermore, the speech-in-noise (SIN) threshold was negatively correlated with the noise-induced change in H2 (for FFRENV) and the S-R correlation for FFRENV in the quiet condition.Conclusion: Audibility affects the subcortical encoding of both envelope and TFS in PC patients. The impaired ability to adjust the balance between the envelope and TFS in the noise condition may be part of the mechanism underlying PC-related deficits in speech recognition in noise. FFRs can predict SIN perception performance.

Bridging the brain structure—brain function gap in prosodic speech processing in older adults

Speech motor resources may be recruited to assist challenging speech perception in younger normally hearing listeners, but the extent to which this occurs for older adult listeners is unclear. We investigated if speech motor resources are also recruited in older adults during speech perception. Specifically, we investigated if suppression of speech motor resources via sub-vocal rehearsal affects speech perception compared to non-speech motor suppression (jaw movement) and passive listening. Participants identified words in speech-shaped noise at signal-to-noise ratios (SNRs) from -16 to +16 dB in three listening conditions during which participants: (1) opened and closed their jaw (non-speech movement); (2) sub-vocally mimed ‘the’ (articulatory suppression); (3) produced no concurrent movement (passive listening). Data from 46 younger adults (M age = 20.17 years, SD = 1.61, 36 female) and 41 older adults (M age = 69 years, SD = 5.82, 21 female) were analysed. Linear mixed effects modelling investigated the impact of age, listening condition, and self-reported hearing ability on speech perception (d’ prime). Results indicated that speech perception ability was significantly worse in older adults relative to younger adults across all listening conditions. A significant interaction between age group and listening condition indicated that younger adults showed poorer performance during articulatory suppression compared to passive listening, but older adults performed equivalently across conditions. This finding suggests that speech motor resources are less available to support speech perception in older adults, providing important insights for auditory-motor integration for speech understanding and communication in ageing.

Previous studies have found that perception in older people benefits from multisensory over unisensory information. As normal speech recognition is affected by both the auditory input and the visual lip movements of the speaker, we investigated the efficiency of audio and visual integration in an older population by manipulating the relative reliability of the auditory and visual information in speech. We also investigated the role of the semantic context of the sentence to assess whether audio–visual integration is affected by top-down semantic processing. We presented participants with audio–visual sentences in which the visual component was either blurred or not blurred. We found that there was a greater cost in recall performance for semantically meaningless speech in the audio–visual ‘blur’ compared to audio–visual ‘no blur’ condition and this effect was specific to the older group. Our findings have implications for understanding how aging affects efficient multisensory integration for the perception of speech and suggests that multisensory inputs may benefit speech perception in older adults when the semantic content of the speech is unpredictable.

Speech-in-noise (SIN) perception is one of the most complex tasks faced by listeners on a daily basis. Although listening in noise presents challenges for all listeners, background noise inordinately affects speech perception in older adults and in children with learning disabilities. Hearing thresholds are an important factor in SIN perception, but they are not the only factor. For successful comprehension, the listener must perceive and attend to relevant speech features, such as the pitch, timing, and timbre of the target speaker's voice. Here, we review recent studies linking SIN and brainstem processing of speech sounds. To review recent work that has examined the ability of the auditory brainstem response to complex sounds (cABR), which reflects the nervous system's transcription of pitch, timing, and timbre, to be used as an objective neural index for hearing-in-noise abilities. We examined speech-evoked brainstem responses in a variety of populations, including children who are typically developing, children with language-based learning impairment, young adults, older adults, and auditory experts (i.e., musicians). In a number of studies, we recorded brainstem responses in quiet and babble noise conditions to the speech syllable /da/ in all age groups, as well as in a variable condition in children in which /da/ was presented in the context of seven other speech sounds. We also measured speech-in-noise perception using the Hearing-in-Noise Test (HINT) and the Quick Speech-in-Noise Test (QuickSIN). Children and adults with poor SIN perception have deficits in the subcortical spectrotemporal representation of speech, including low-frequency spectral magnitudes and the timing of transient response peaks. Furthermore, auditory expertise, as engendered by musical training, provides both behavioral and neural advantages for processing speech in noise. These results have implications for future assessment and management strategies for young and old populations whose primary complaint is difficulty hearing in background noise. The cABR provides a clinically applicable metric for objective assessment of individuals with SIN deficits, for determination of the biologic nature of disorders affecting SIN perception, for evaluation of appropriate hearing aid algorithms, and for monitoring the efficacy of auditory remediation and training.

Figure: Concussion, Hearing. iStockPhoto/SeregaAn estimated 2 million to 4 million sports-related traumatic brain injuries (TBI) occur annually in the United States (J Head Trauma Rehabil. 2006;21[5]:375 http://bit.ly/2k8lxc5). The Centers for Disease Control and Prevention estimates that about 5.3 million Americans are living with long-term disabilities associated with TBI (J Head Trauma Rehabil. 2006 http://bit.ly/2k8lxc5). A major subclass of these injuries is concussion, defined as a diffuse, non-penetrating brain injury following a sudden impact (Nat Rev Neurol. 2015;11[4]:230 http://bit.ly/2k8vWUT). A person can get a concussion in any circumstance, but those suffered a concussion from playing sports have received tremendous public interest. Prominent athletes have retired following serious concussions, and a growing number of reports link repeated concussions or subconcussive head impact to lasting brain damage. Even former President Barack Obama weighed in, famously saying that if he had a son, he would not let him play professional football (CBS Sports, Jan. 2014 http://cbsprt.co/2k8qUb9). This public attention has motivated increased research into concussion science. However, there is currently no single test to identify a concussion. A clinician must consider an array of potential symptoms. And what is perhaps even more challenging is the lack of a gold standard test to indicate when an individual has completely recovered from a concussion. FFR FOR CONCUSSION IDENTIFICATIONFigure: Nina Kraus, PhDWe tested a new approach to identify concussions: the frequency-following response (FFR), an electrophysiological measure of sound-evoked synchronous neural activity. Making sense of sound is one of the brain's most difficult tasks, and an individual suffering from a concussion struggles to understand sound in complex listening environments. These observations motivated the hypothesis that measuring fine-grained neural processes could indicate the presence of a concussion.Figure: Travis White-SchwochTo test this hypothesis, we measured the FFRs of adolescents diagnosed with a concussion in a sports medicine clinic (Nature: Sci Rep. 2016;6:39009 http://go.nature.com/2k8ulyJ). We found that neural responses to the fundamental frequency (F0) were disrupted after a concussion—they were about 30 percent lower and more sluggish than in healthy controls. The F0 is an important pitch-bearing cue for identifying sounds. For example, male and female voices are distinguished by their F0s; thus, tracking a speaker's F0 can facilitate speech understanding in a difficult listening situation. It makes sense, then, that the neural processing of this sound feature, and not others, is disrupted by a blow to the head. And discussed in previous columns in The Hearing Journal, the strength of coding the F0 tracks the ability to understand speech in noise (Hear Res. 2013;300:18 http://bit.ly/2k8q5iq). We then tried to use the FFR to identify individuals with concussions, and found that the FFR accurately identified 90 percent of concussion patients and 95 percent of control patients. The FFR also tracked the symptom severity of a concussion; children, who reported the greatest symptom loads from injuries, had the lowest F0 responses. Additionally, we found that the FFR to the F0 improved as patients recovered, suggesting that FFR can be used to track recovery. FFR FOR CONCUSSION MANAGEMENT The FFR has many features that make it an attractive approach to augment concussion management. It is a fast and portable test, with available norms for patients of different ages (Cereb Cortex. 2015;25[6]:1415 http://bit.ly/2k8mrVZ). It also has a good test-to-test reliability. Perhaps the most useful feature of FFR for concussion management is that it does not require patients to do anything during the test—patients may sleep or watch a movie while the test is going on. Compared with other cognitive and behavioral tasks, FFR testing assures objective monitoring of concussions as patients cannot will themselves to perform at a certain level when undergoing this test. This is notably a distinctive and beneficial feature of FFR. Moreover, this test indicates meaningful individual differences in sound processing, making it an excellent approach for longitudinal monitoring. For example, an athlete could receive a baseline FFR prior to engaging in activities and be tested for deviations whenever a concussion is suspected. While these results are promising, it is important to acknowledge that this study was just a proof of concept. The next step is to replicate these findings in a larger and more diverse sample. Should the FFR pan out as an approach to identify concussions, there are many potential outlets for its use. For example, the FFR could be used to track an individual's recovery from the concussion. When the brain response normalizes to a patient's pre-injury baseline, it might signal that it is safe for that individual to resume full participation in sports. The FFR could also be an approach to arbitrate between different concussion management strategies. For example, brain rest might be the best approach for some patients, whereas other patients might need exercise or cognitive rehabilitation. Concussion management is best tackled by an interdisciplinary team, including physicians, athletic trainers, and speech-language pathologists. But with the introduction of this measure of brain sound processing, audiologists may be able to collaborate with these health professionals in identifying and managing concussions. Our hope is that this discovery provides a new tool for clinical teams to make the best health decisions for athletes and sports enthusiasts.

Simultaneous recordings of the brain stem response and the frequency-following response to low-frequency tone

Understanding speech in noise (SIN) is the dominant complaint of individuals with hearing loss. For decades, the default test of speech perception in routine audiologic assessment has been monosyllabic word recognition in quiet (WRQ), which does not directly address patient concerns, leading some to advocate that measures of SIN should be integrated into routine practice. However, very little is known with regard to how SIN abilities are affected by different types of hearing loss. Here, we examine performance on clinical measures of WRQ and SIN in a large patient base consisting of a variety of hearing loss types, including conductive (CHL), mixed (MHL), and sensorineural (SNHL) losses. In a retrospective study, we examined data from 5593 patients (51% female) who underwent audiometric assessment at the Stanford Ear Institute. All individuals completed pure-tone audiometry, and speech perception testing of monaural WRQ, and monaural QuickSIN. Patient ages ranged from 18 to 104 years (average = 57). The average age in years for the different classifications of hearing loss was 51.1 (NH), 48.5 (CHL), 64.2 (MHL), and 68.5 (SNHL), respectively. Generalized linear mixed-effect models and quartile regression were used to determine the relationship between hearing loss type and severity for the different speech-recognition outcome measures. Patients with CHL had similar performance to patients with normal hearing on both WRQ and QuickSIN, regardless of the hearing loss severity. In patients with MHL or SNHL, WRQ scores remained largely excellent with increasing hearing loss until the loss was moderately severe or worse. In contrast, QuickSIN signal to noise ratio (SNR) losses showed an orderly systematic decrease as the degree of hearing loss became more severe. This effect scaled with the data, with threshold-QuickSIN relationships absent for CHL, and becoming increasingly stronger for MHL and strongest in patients with SNHL. However, the variability in these data suggests that only 57% of the variance in WRQ scores, and 50% of the variance in QuickSIN SNR losses, could be accounted for by the audiometric thresholds. Patients who would not be differentiated by WRQ scores are shown to be potentially differentiable by SIN scores. In this data set, conductive hearing loss had little effect on WRQ scores or QuickSIN SNR losses. However, for patients with MHL or SNHL, speech perception abilities decreased as the severity of the hearing loss increased. In these data, QuickSIN SNR losses showed deficits in performance with degrees of hearing loss that yielded largely excellent WRQ scores. However, the considerable variability in the data suggests that even after classifying patients according to their type of hearing loss, hearing thresholds only account for a portion of the variance in speech perception abilities, particularly in noise. These results are consistent with the idea that variables such as cochlear health and aging add explanatory power over audibility alone.

To determine whether significant differences in cochlear implant (CI) performance exist between older and younger CI recipients. Retrospective comparison of audiometric data. University hospital center. Sixty participants who received CIs at age 70 and older and 48 younger adults implanted between age 18 and 69. Speech outcome scores (Consonant-Nucleus-Consonant words and phonemes and City University of New York Sentence test in quiet and noise). Older participants show significant improvement in speech perception scores after implantation. Although on average they do not perform as well as younger adults, this difference correlates with duration of deafness rather than age. In contrast to younger adults, significant differences in CI performance are seen in older recipients depending on the side of implantation, with those implanted on the right performing better than those implanted on the left. Postlingually deafened older adults obtained significant speech perception benefits from CIs, although differences in speech outcomes were seen between younger recipients and those implanted after age 70. In older adults considering CIs, hearing benefits appear greater if they are implanted in the right ear.

ObjectiveWe aimed to study the effect of background noise on speech auditory evoked responses in both normal-hearing (NH) individuals and those with sensorineural hearing loss (SNHL) and correlate these neurophysiological results with subjective measures.BackgroundUnderstanding speech in noisy situations is one of the most complex activities encountered in everyday life. It is dependent on cognitive factors and sound processing at peripheral, subcortical, and cortical levels. These make perception of speech in noise one of the most complex aspects of human communication.Patients and methodsFifty NH individuals and 40 individuals with mild-to-moderate SNHL were subjected to the Speech, Spatial, and Qualities of Hearing Scale questionnaire, the speech perception in noise test, speech auditory brainstem response, and cortical auditory evoked responses using speech syllable/da/in quiet condition and at three different signal-to-noise ratios (SNRs) (+10, 0, and − 10).ResultsSpeech auditory brainstem response results in NH participants showed delayed latencies of both transients (waves V, A, C, and O) and frequency-following response with reduction in amplitudes of onset (V and A) and F wave only in noisy relative to quiet condition, whereas in SNHL delayed latencies and decreased amplitudes of both transients and fractional flow reserve (FFR) were observed. The effect of noise can be seen in all waves of cortical auditory evoked responses – that is, with decreasing SNR response, latency increased and response amplitude decreased in both SNHL and NH.ConclusionBackground noise affects both transients and sustained components of speech in NH and SNHL. P1, N1, P2, and N2 components are all affected by SNR, despite their distinct neural generators; this raises the possibility that the effects demonstrated here are reflective of subcortical processing that is propagated to higher levels of the auditory system. cocktail party, speech auditory brainstem response, speech-in-noise perception

By 24 mo of age, most typically developing infants with normal hearing successfully transition to the production of words that can be understood about 50% of the time. This study compares early phonological development in children with and without hearing loss to gain a clearer understanding of the effects of hearing loss in early-identified children. A secondary goal was to identify measures of early phonetic development that are predictors of later speech production outcomes. The vocalizations and early words of 21 infants with normal hearing and 12 early-identified infants with hearing loss were followed longitudinally over a period of 14 mo (from 10 to 24 mo of age). Thirty-minute mother-child interaction samples were video recorded at 6- to 8-wk intervals in a laboratory playroom setting. Vocalizations produced at 16 and 24 mo were categorized according to communicative intent and recognizable words versus other types. Groups were compared on the structural complexity of words produced at 24 mo of age. Parent report measures of vocabulary development were collected from 10 to 30 mo of age, and Goldman-Fristoe Test of Articulation scores at 36 mo were used in regression analyses. Both groups increased the purposeful use of voice between 16 and 24 mo of age. However, at 24 mo of age, the toddlers with hearing loss produced significantly fewer words that could be recognized by their mothers. Their samples were dominated by unintelligible communicative attempts at this age. In contrast, the samples from normal hearing children were dominated by words and phrases. At 24 mo of age, toddlers with normal hearing were more advanced than those with hearing loss on seven measures of the structural complexity of words. The children with normal hearing attempted more complex words and productions were more accurate than those of children with hearing loss. At 10 to 16 mo of age, the groups did not differ significantly on parent-report measures of receptive vocabulary. However, the hearing loss group was much slower to develop expressive vocabulary and demonstrated larger individual differences than the normal hearing group. Six children identified as atypical differed from all other children in vowel accuracy and complexity of word attempts. However, both atypical infants and typical infants with hearing loss were significantly less accurate than normal hearing infants in consonant and word production. Early measures of syllable production predicted unique variance in later speech production and vocabulary outcomes. The transition from babble to words in infants with hearing loss appears to be delayed but parallel to that of infants with normal hearing. These delays appear to exert significant influences on expressive vocabulary development. Parents may appreciate knowing that some children with hearing loss may develop early vocabulary at a slower rate than children with normal hearing. Clinicians should monitor landmarks from babble onset through transitions to words. Indicators of atypical development were delayed and/or limited use of syllables with consonants, vowel errors and limited production of recognizable words.

要旨: ことばの聞き取りに重要な時間情報の処理には, 時間分解能が関係している。本研究では, 純音聴力レベルが 20dBHL 以下の高齢者15名 (平均年齢: 71.4歳) を対象に, ギャップ前後の刺激音の周波数を変化させた (条件①: 800-1600Hz, 条件②: 800-3200Hz), 周波数間ギャップ検出閾値検査を実施した。ギャップサイズは 150ms から適応法にて 1up-2down で上下するよう設定し, ギャップ検出閾値を求め, 若年者と比較した。高齢者は若年者に比し,有意に閾値上昇を認めた。また高齢者に複数の聴取検査を実施し, ギャップ検出閾値と語音聴取との関係を検討した。条件①②共に聴覚的注意検査と, 条件②と複数音声下聴取検査で相関を認めた。周波数間ギャップ検出閾値は, 注意のシフトのような何らかの注意機能が関与すると言われている。高齢者は聴力だけでなく, 認知機能も聞き取りに影響を及ぼすとされる。加齢の影響がどのように認知機能や聴取に影響を及ぼすか, 聞き取りを多面的に捉えることが重要である。

The purpose of this study was to analyze distortion product otoacoustic emission (DPOAE) level and signal to noise ratio in a group of infants from birth to 4 months of age to optimize prediction of hearing status. DPOAEs from infants with normal hearing (NH) and hearing loss (HL) were used to predict the presence of conductive HL (CHL), sensorineural HL (SNHL), and mixed HL (MHL). Wideband ambient absorbance was also measured and compared among the HL types. This is a prospective, longitudinal study of 279 infants with verified NH and HL, including conductive, sensorineural, and mixed types that were enrolled from a well-baby nursery and two neonatal intensive care units in Cincinnati, Ohio. At approximately 1 month of age, DPOAEs (1-8 kHz), wideband absorbance (0.25-8 kHz), and air and bone conduction diagnostic tone burst auditory brainstem response (0.5-4 kHz) thresholds were measured. Hearing status was verified at approximately 9 months of age with visual reinforcement audiometry (0.5-4 kHz). Auditory brainstem response air conduction thresholds were used to assign infants to an NH or HL group, and the efficacy of DPOAE data to classify ears as NH or HL was analyzed using receiver operating characteristic (ROC) curves. Two summary statistics of the ROC curve were calculated: the area under the ROC curve and the point of symmetry on the curve at which the sensitivity and specificity were equal. DPOAE level and signal to noise ratio cutoff values were defined at each frequency as the symmetry point on their respective ROC curve, and DPOAE results were combined across frequency in a multifrequency analysis to predict the presence of HL. Single-frequency test performance of DPOAEs was best at mid to high frequencies (3-8 kHz) with intermediate performance at 1.5 and 2 kHz and chance performance at 1 kHz. Infants with a conductive component to their HL (CHL and MHL combined) displayed significantly lower ambient absorbance values than the NH group. No differences in ambient absorbance were found between the NH and SNHL groups. Multifrequency analysis resulted in the best prediction of HL for the SNHL/MHL group with poorer sensitivity values when infants with CHL were included. Clinical interpretation of DPOAEs in infants can be improved by using age-appropriate normative ranges and optimized cutoff values. DPOAE interpretation is most predictive at higher F2 test frequencies in young infants (2-8 kHz) due to poor test performance at 1 to 1.5 kHz. Multifrequency rules can be used to improve sensitivity while balancing specificity. Last, a sensitive middle ear measure such as wideband absorbance should be included in the test battery to assess possibility of a conductive component to the HL.