Favorable Listening Conditions Research Articles

Orthographic information facilitates discrimination of native and foreign-accented speech

Previous research on the perception of foreign-accented speech has demonstrated that providing orthographic transcriptions of auditory stimulus words influences accentedness ratings of the talker. Specifically, foreign-accented talkers are rated as having less accented speech in favorable listening conditions when orthographic information is present. Cochlear implant users show poor identification and discrimination of foreign-accented speech relative to listeners with normal hearing. In the current study, we examined whether orthographic information facilitates the discrimination of native and foreign-accented (non-native) speech under cochlear-implant simulation. Participants were presented with native or foreign-accented sentences through an eight-channel noise vocoder with or without matching text. They were asked to determine whether the sentence was spoken by a native or non-native talker. We hypothesized that the presence of matching text would increase identification accuracy and decrease reaction time. Consistent with our predictions, participants more accurately and more quickly identified whether sentences were spoken by a non-native talker in the presence of matching text compared to performance in conditions with no text. These results suggest that the presence of orthographic information may facilitate indexical, non-linguistic perception under cochlear-implant simulation. Future work will determine whether these results may extend to cochlear implant users.

Plasticity Changes in Central Auditory Systems of School-Age Children Following a Brief Training With a Remote Microphone System.

The objective of this study was to investigate whether a brief speech-in-noise training with a remote microphone (RM) system (favorable listening condition) would contribute to enhanced post-training plasticity changes in the auditory system of school-age children. Before training, event-related potentials (ERPs) were recorded from 49 typically developing children, who actively identified two syllables in quiet and in noise (+5 dB signal-to-noise ratio [SNR]). During training, children completed the same syllable identification task as in the pre-training noise condition, but received feedback on their performance. Following random assignment, half of the sample used an RM system during training (experimental group), while the other half did not (control group). That is, during training' children in the experimental group listened to a more favorable speech signal (+15 dB SNR) than children from the control group (+5 dB SNR). ERPs were collected after training at +5 dB SNR to evaluate the effects of training with and without the RM system. Electrical neuroimaging analyses quantified the effects of training in each group on ERP global field power (GFP) and topography, indexing response strength and network changes, respectively. Behavioral speech-perception-in-noise skills of children were also evaluated and compared before and after training. We hypothesized that training with the RM system (experimental group) would lead to greater enhancement of GFP and greater topographical changes post-training than training without the RM system (control group). We also expected greater behavioral improvement on the speech-perception-in-noise task when training with than without the RM system. GFP was enhanced after training only in the experimental group. These effects were observed on early time-windows corresponding to traditional P1-N1 (100 to 200 msec) and P2-N2 (200 to 400 msec) ERP components. No training effects were observed on response topography. Finally, both groups increased their speech-perception-in-noise skills post-training. Enhanced GFP after training with the RM system indicates plasticity changes in the neural representation of sound resulting from listening to an enriched auditory signal. Further investigation of longer training or auditory experiences with favorable listening conditions is needed to determine if that results in long-term speech-perception-in-noise benefits.

Learning and bilingualism in challenging listening conditions: How challenging can it be?

When speech is presented in their second language (L2), bilinguals have more difficulties with speech perception in noise than monolinguals do. However, how noise affects speech perception of bilinguals in their first language (L1) is still unclear. In addition, it is not clear whether bilinguals' speech perception in challenging listening conditions is specific to the type of degradation, or whether there is a shared mechanism for bilingual speech processing under complex listening conditions. Therefore, the current study examined the speech perception of 60 Arabic-Hebrew bilinguals and a control group of native Hebrew speakers during degraded (speech in noise, vocoded speech) and quiet listening conditions. Between participant comparisons (comparing native Hebrew speakers and bilinguals' perceptual performance in L1) and within participant comparisons (perceptual performance of bilinguals in L1 and L2) were conducted. The findings showed that bilinguals in L1 had more difficulty in noisy conditions than their control counterparts did, even when performed like controls under favorable listening conditions. However, bilingualism did not hinder language learning mechanisms. Bilinguals in L1 outperformed native Hebrew speakers in the perception of vocoded speech, demonstrating more extended learning processes. Bilinguals' perceptual performance in L1 versus L2 varied by task complexity. Correlation analyses revealed that bilinguals who coped better with noise degradation were more successful in perceiving the vocoding distortion. Together, these results provide insights into the mechanisms that contribute to speech perceptual performance in challenging listening conditions and suggest that bilinguals' language proficiency and age of language acquisition are not the only factors that affect performance. Rather, duration of exposure to languages, co-activation, and the ability to benefit from exposure to novel stimuli appear to affect the perceptual performance of bilinguals, even when operating in their dominant language. Our findings suggest that bilinguals use a shared mechanism for speech processing under challenging listening conditions.

Effect of Spectral Channels on Speech Recognition, Comprehension, and Listening Effort in Cochlear-Implant Users.

In favorable listening conditions, cochlear-implant (CI) users can reach high speech recognition scores with as little as seven active electrodes. Here, we hypothesized that even when speech recognition is high, additional spectral channels may still benefit other aspects of speech perception, such as comprehension and listening effort. Twenty-five adult, postlingually deafened CI users, selected from two Dutch implant centers for high clinical word identification scores, participated in two experiments. Experimental conditions were created by varying the number of active electrodes of the CIs between 7 and 15. In Experiment 1, response times (RTs) on the secondary task in a dual-task paradigm were used as an indirect measure of listening effort, and in Experiment 2, sentence verification task (SVT) accuracy and RTs were used to measure speech comprehension and listening effort, respectively. Speech recognition was near ceiling for all conditions tested, as intended by the design. However, the dual-task paradigm failed to show the hypothesized decrease in RTs with increasing spectral channels. The SVT did show a systematic improvement in both speech comprehension and response speed across all conditions. In conclusion, the SVT revealed additional benefits in both speech comprehension and listening effort for conditions in which high speech recognition was already achieved. Hence, adding spectral channels may provide benefits for CI listeners that may not be reflected by traditional speech tests. The SVT is a relatively simple task that is easy to implement and may therefore be a good candidate for identifying such additional benefits in research or clinical settings.

About Face: Seeing the Talker Improves Spoken Word Recognition but Increases Listening Effort.

It is widely accepted that seeing a talker improves a listener’s ability to understand what a talker is saying in background noise (e.g., Erber, 1969; Sumby & Pollack, 1954). The literature is mixed, however, regarding the influence of the visual modality on the listening effort required to recognize speech (e.g., Fraser, Gagné, Alepins, & Dubois, 2010; Sommers & Phelps, 2016). Here, we present data showing that even when the visual modality robustly benefits recognition, processing audiovisual speech can still result in greater cognitive load than processing speech in the auditory modality alone. We show using a dual-task paradigm that the costs associated with audiovisual speech processing are more pronounced in easy listening conditions, in which speech can be recognized at high rates in the auditory modality alone—indeed, effort did not differ between audiovisual and audio-only conditions when the background noise was presented at a more difficult level. Further, we show that though these effects replicate with different stimuli and participants, they do not emerge when effort is assessed with a recall paradigm rather than a dual-task paradigm. Together, these results suggest that the widely cited audiovisual recognition benefit may come at a cost under more favorable listening conditions, and add to the growing body of research suggesting that various measures of effort may not be tapping into the same underlying construct (Strand et al., 2018).

Tone language experience-dependent advantage in pitch representation in brainstem and auditory cortex is maintained under reverberation

Long-term language and music experience enhances neural representation of temporal attributes of pitch in the brainstem and auditory cortex in favorable listening conditions. Herein we examine whether brainstem and cortical pitch mechanisms—shaped by long-term language experience—maintain this advantage in the presence of reverberation-induced degradation in pitch representation. Brainstem frequency following responses (FFR) and cortical pitch responses (CPR) were recorded concurrently from Chinese and English-speaking natives, using a Mandarin word exhibiting a high rising pitch (/yi2/). Stimuli were presented diotically in quiet (Dry), and in the presence of Slight, Mild, and Moderate reverberation conditions. Regardless of language group, the amplitude of both brainstem FFR (F0) and cortical CPR (NaPb) responses decreased with increases in reverberation. Response amplitude for Chinese, however, was larger than English in all reverberant conditions. The Chinese group also exhibited a robust rightward asymmetry at temporal electrode sites (T8 > T7) across stimulus conditions. Regardless of language group, direct comparison of brainstem and cortical responses revealed similar magnitude of change in response amplitude with increasing reverberation. These findings suggest that experience-dependent brainstem and cortical pitch mechanisms provide an enhanced and stable neural representation of pitch-relevant information that is maintained even in the presence of reverberation. Relatively greater degradative effects of reverberation on brainstem (FFR) compared to cortical (NaPb) responses suggest relatively stronger top-down influences on CPRs.

A Matrixed Speech-in-Noise Test to Discriminate Favorable Listening Conditions by Means of Intelligibility and Response Time Results.

The primary aim of this study was to develop and examine the potentials of a new speech-in-noise test in discriminating the favorable listening conditions targeted in the acoustical design of communication spaces. The test is based on the recognition and recall of disyllabic word sequences. A secondary aim was to compare the test with current speech-in-noise tests, assessing its benefits and limitations. Young adults (19-40 years old), self-reporting normal hearing, were presented with the newly developed Words Sequence Test (WST; 16 participants, Experiment 1) and with a consonant confusion test and a sentence recognition test (Experiment 2, 36 participants randomly assigned to the 2 tests). Participants performing the WST were presented with word sequences of different lengths (from 2 up to 6 words). Two listening conditions were selected: (a) no noise and no reverberation, and (b) reverberant, steady-state noise (Speech Transmission Index: 0.47). The tests were presented in a closed-set format; data on the number of words correctly recognized (speech intelligibility, IS) and the response times (RTs) were collected (onset RT, single words' RT). It was found that a sequence composed of 4 disyllabic words ensured both the full recognition score in quiet conditions and a significant decrease in IS results when noise and reverberation degraded the speech signal. RTs increased with the worsening of the listening conditions and the number of words of the sequence. The greatest onset RT variation was found when using a sequence of 4 words. In the comparison with current speech-in-noise tests, it was found that the WST maximized the IS difference between the selected listening conditions as well as the RT increase. Overall, the results suggest that the new speech-in-noise test has good potentials in discriminating conditions with near-ceiling accuracy. As compared with current speech-in-noise tests, it appears that the WST with a 4-word sequence allows for a finer mapping of the acoustical design target conditions of public spaces through accuracy and onset RT data.

Language experience-dependent advantage in pitch representation in the auditory cortex is limited to favorable signal-to-noise ratios

Long-term experience enhances neural representation of temporal attributes of pitch in the brainstem and auditory cortex in favorable listening conditions. Herein we examine whether cortical pitch mechanisms shaped by language experience are more resilient to degradation in background noise, and exhibit greater binaural release from masking (BRM). Cortical pitch responses (CPR) were recorded from Mandarin- and English-speaking natives using a Mandarin word exhibiting a high rising pitch (/yi2/). Stimuli were presented diotically in Quiet, and in noise at +5, and 0 dB SNR. CPRs were also recorded in binaural conditions, SONO (where signal and noise were in phase at both ears); or S0Nπ (where signal was in phase and noise 180° out of phase at each ear), using 0 dB SNR. At Fz, both groups showed increase in CPR peak latency and decrease in amplitude with increasing noise level. A language-dependent enhancement of Na–Pb amplitude (Chinese > English) was restricted to Quiet and +5 dB SNR conditions. At T7/T8 electrode sites, Chinese natives exhibited a rightward asymmetry for both CPR components. A language-dependent effect (Chinese > English) was restricted to T8. Regarding BRM, both CPR components showed greater response amplitude for the S0Nπ condition compared to S0N0 across groups. Rightward asymmetry for BRM in the Chinese group indicates experience-dependent recruitment of right auditory cortex. Restriction of the advantage in pitch representation to the quiet and +5 SNR conditions, and the absence of group differences in the binaural release from masking, suggest that language experience affords limited advantage in the neural representation of pitch-relevant information in the auditory cortex under adverse listening conditions.

Perception of Consonants in Speech-Shaped Noise among Young and Middle-Aged Adults.

The present study was carried out to compare the consonant perception of young and middle-aged adults in quiet and noisy listening conditions. Twenty-nine adults aged between 18 and 55 years old participated in the study, and were separated into two groups based on their age: Group I, comprising 15 young adults aged between 18 and 40 years old, and Group II, comprising 14 middle-aged adults aged between 41 and 55 years old. All the participants had normal hearing sensitivity in both ears. Consonant perception was better in favorable listening conditions for both young and middle-aged adults. Comparison of the consonant identification scores of young and middle-aged adults showed significantly poorer scores among middle-aged adults in both quiet and noisy listening conditions. The findings of the present study reveal that middle-aged adults have small but significant consonant perception difficulties compared to younger adults in quiet and noisy listening conditions.

On the color of speech: The effect of speaking styles on speech recognition by cochlear-implant users

Speaking styles are a common source of real-life variability that may affect cochlear implant (CI) speech communication. Speech transmitted via a CI is heavily degraded in acoustic-phonetic cues. Therefore, the extent to which (and for what conditions) individual CI users benefit from carefully articulated speech (or are hindered by casually articulated/reduced speech) is unclear. First, we examined the impact of speaking styles on CI speech recognition in favorable listening conditions. CI users and normal-hearing (NH) listeners tested with 8- and 4-channel acoustic CI simulations completed a sentence recognition task with casual and careful sentences (with similar lexical and semantic content) in the quiet. Second, we explored individual performance on this task and its relation with standard speech recognition scores and self-reported real-life hearing abilities. Listeners were overall more accurate on careful sentences than the casual sentences, but casual sentences were disproportionately more diffic...

Dialectal Effects on a Clinical Spanish Word Recognition Test

American Spanish dialects have substantial phonetic and lexical differences. This study investigated how dialectal differences affect Spanish/English bilingual individuals’ performance on a clinical Spanish word recognition test. Forty Spanish/English bilinguals participated in the study—20 dominant in Spanish and 20 in English.Within each group, 10 listeners spoke the Highland dialect, and 10 spoke the Caribbean/Coastal dialect. Participants were maximally matched between the 2 dialectal groups regarding their demographic and linguistic background. Listeners were randomly presented 4 lists of Auditec Spanish bisyllabic words at 40 dB SL re: pure-tone average. Each list was randomly assigned with a signal-to-noise ratio (SNR) of quiet, +6, +3, and 0 dB, in the presence of speech-spectrum noise. Listeners responded orally and in writing. Dialect and language dominance both significantly affected listener performance on the word recognition test. Higher performance levels were obtained with Highland than Caribbean/Coastal listeners and with Spanish-dominant than English-dominant listeners. The dialectal difference was particularly evident in favorable listening conditions (i.e., quiet and +6 dB SNR) and could not be explained by listeners’ familiarity with the test words. Dialects significantly affect the clinical assessment of Spanish-speaking clients’ word recognition. Clinicians are advised to consider the phonetic features of the dialect when scoring a client’s performance.

Benefits of Combined Acoustic and Electric Hearing for Music and Pitch Perception

The total number of cochlear implant (CI) recipients worldwide is now approaching 200,000. Most current CI users attain an adequate ability to understand speech using the implant alone, despite having had at least severe to profound hearing impairment in both ears preoperatively. The satisfactory technical performance of modern CI systems, at least in favorable listening conditions, has resulted in an increasing proportion of CI recipients having usable acoustic hearing postoperatively in one ear, or even in both ears. Many studies have confirmed that, in general, the simultaneous use of acoustic and electric hearing can provide perceptual benefits in comparison to the use of a CI alone. An especially important advantage conferred by the use of acoustic hearing is the potentially improved ability of CI recipients to perceive musical sounds. In particular, the perception of pitch, which is usually not provided adequately by today's CI systems, can be enhanced when sounds are heard acoustically by CI users with sufficient hearing sensitivity.

Music and Cochlear Implants

Music and Cochlear Implants

Perception of Dialect Variation in Noise: Intelligibility and Classification

Listeners can explicitly categorize unfamiliar talkers by regional dialect with above-chance performance under ideal listening conditions. However, the extent to which this important source of variation affects speech processing is largely unknown. In a series of four experiments, we examined the effects of dialect variation on speech intelligibility in noise and the effects of noise on perceptual dialect classification. Results revealed that, on the one hand, dialect-specific differences in speech intelligibility were more pronounced at harder signal-to-noise ratios, but were attenuated under more favorable listening conditions. Listener dialect did not interact with talker dialect; for all listeners, at a range of noise levels, the General American talkers were the most intelligible and the Mid-Atlantic talkers were the least intelligible. Dialect classification performance, on the other hand, was poor even with only moderate amounts of noise. These findings suggest that at moderate noise levels, listeners are able to adapt to dialect variation in the acoustic signal such that some cross-dialect intelligibility differences are neutralized, despite relatively poor explicit dialect classification performance. However, at more difficult noise levels, participants cannot effectively adapt to dialect variation in the acoustic signal and cross-dialect differences in intelligibility emerge for all listeners, regardless of their dialect.

Music Perception with Cochlear Implants: A Review

The acceptance of cochlear implantation as an effective and safe treatment for deafness has increased steadily over the past quarter century. The earliest devices were the first implanted prostheses found to be successful in compensating partially for lost sensory function by direct electrical stimulation of nerves. Initially, the main intention was to provide limited auditory sensations to people with profound or total sensorineural hearing impairment in both ears. Although the first cochlear implants aimed to provide patients with little more than awareness of environmental sounds and some cues to assist visual speech-reading, the technology has advanced rapidly. Currently, most people with modern cochlear implant systems can understand speech using the device alone, at least in favorable listening conditions. In recent years, an increasing research effort has been directed towards implant users' perception of nonspeech sounds, especially music. This paper reviews that research, discusses the published experimental results in terms of both psychophysical observations and device function, and concludes with some practical suggestions about how perception of music might be enhanced for implant recipients in the future. The most significant findings of past research are: (1) On average, implant users perceive rhythm about as well as listeners with normal hearing; (2) Even with technically sophisticated multiple-channel sound processors, recognition of melodies, especially without rhythmic or verbal cues, is poor, with performance at little better than chance levels for many implant users; (3) Perception of timbre, which is usually evaluated by experimental procedures that require subjects to identify musical instrument sounds, is generally unsatisfactory; (4) Implant users tend to rate the quality of musical sounds as less pleasant than listeners with normal hearing; (5) Auditory training programs that have been devised specifically to provide implant users with structured musical listening experience may improve the subjective acceptability of music that is heard through a prosthesis; (6) Pitch perception might be improved by designing innovative sound processors that use both temporal and spatial patterns of electric stimulation more effectively and precisely to overcome the inherent limitations of signal coding in existing implant systems; (7) For the growing population of implant recipients who have usable acoustic hearing, at least for low-frequency sounds, perception of music is likely to be much better with combined acoustic and electric stimulation than is typical for deaf people who rely solely on the hearing provided by their prostheses.

Speech perception in older adults: the importance of speech-specific cognitive abilities.

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.