Listeners Benefit Research Articles

The perception and production of Mandarin-accented English: The role of degree of accentedness in the interlanguage speech intelligibility benefit for talkers and the interlanguage speech intelligibility benefit for listeners

The Interlanguage Speech Intelligibility Benefit for talkers (ISIB-T) claims non-native learners are better at understanding talkers with a shared L1 than they are at understanding native talkers, and the ISIB for listeners (ISIB-L) claims non-native learners are better at understanding talkers with a shared L1 than native speakers are (Hayes-Harb et al., 2008). In the present study, a lexical decision task (including words with shared phonemes in both Mandarin and English, as well as words with phonemes that only occur in English) was used, with accentedness ratings of talkers and listeners collected to investigate whether ISIB is manifested differently for listeners and speakers of different proficiency levels. Accuracy scores and reaction time measures were compared for both L1 (native English) and L2 (high proficiency, low proficiency) groups when listening to strongly Mandarin-accented, weakly Mandarin-accented, and native English speech. Amount of Mandarin-accented English input was also measured. Results showed some gradience in accuracy by degree of accentedness, with trends in the predicted direction suggestive of ISIB-T and ISIB-L effects. In addition, participants were more accurate when listening to words with phonemes shared in Mandarin and English than English-specific phoneme words, an advantage that increased as the strength of speaker accent increased.

Recognition of Accented Speech by Cochlear-Implant Listeners: Benefit of Audiovisual Cues.

When auditory and visual speech information are presented together, listeners obtain an audiovisual (AV) benefit or a speech understanding improvement compared with auditory-only (AO) or visual-only (VO) presentations. Cochlear-implant (CI) listeners, who receive degraded speech input and therefore understand speech using primarily temporal information, seem to readily use visual cues and can achieve a larger AV benefit than normal-hearing (NH) listeners. It is unclear, however, if the AV benefit remains relatively large for CI listeners when trying to understand foreign-accented speech when compared with unaccented speech. Accented speech can introduce changes to temporal auditory cues and visual cues, which could decrease the usefulness of AV information. Furthermore, we sought to determine if the AV benefit was relatively larger in CI compared with NH listeners for both unaccented and accented speech. AV benefit was investigated for unaccented and Spanish-accented speech by presenting English sentences in AO, VO, and AV conditions to 15 CI and 15 age- and performance-matched NH listeners. Performance matching between NH and CI listeners was achieved by varying the number of channels of a noise vocoder for the NH listeners. Because of the differences in age and hearing history of the CI listeners, the effects of listener-related variables on speech understanding performance and AV benefit were also examined. AV benefit was observed for both unaccented and accented conditions and for both CI and NH listeners. The two groups showed similar performance for the AO and AV conditions, and the normalized AV benefit was relatively smaller for the accented than the unaccented conditions. In the CI listeners, older age was associated with significantly poorer performance with the accented speaker compared with the unaccented speaker. The negative impact of age was somewhat reduced by a significant improvement in performance with access to AV information. When auditory speech information is degraded by CI sound processing, visual cues can be used to improve speech understanding, even in the presence of a Spanish accent. The AV benefit of the CI listeners closely matched that of the NH listeners presented with vocoded speech, which was unexpected given that CI listeners appear to rely more on visual information to communicate. This result is perhaps due to the one-to-one age and performance matching of the listeners. While aging decreased CI listener performance with the accented speaker, access to visual cues boosted performance and could partially overcome the age-related speech understanding deficits for the older CI listeners.

The effect of synchronized linked band selection on speech intelligibility of bilateral cochlear implant users

Normal-hearing (NH) listeners have the ability to combine the audio input perceived by each ear to extract target information in challenging listening scenarios. Bilateral cochlear implant (BiCI) users, however, do not benefit as much as NH listeners do from a bilateral input. In this study, we investigate the effect that bilaterally synchronized electrical stimulation, bilaterally linked band selection, and ideal binary masks (IdBMs) have on the ability of 10 BiCIs to understand speech in background noise. The performance was assessed through a sentence-based speech intelligibility test, in a scenario where the speech signal was presented from the front and the interfering noise from one side. The linked band selection relies on the most favorable signal-to-noise-ratio (SNR) ear, which will select the bands to be stimulated for both CIs.Speech perception results show that BiCI listeners benefit from adding a second CI to the better-SNR side, obtaining the largest benefit when using bilaterally linked band selection and bilaterally synchronized electrical stimulation. Furthermore, synchronized linked band selection leads to an improvement in speech intelligibility scores when compared to standard clinical BiCI setups. Finally, we observe that by also applying IdBMs, subjects achieve speech intelligibility scores similar to the ones without background noise.

Rhetorical Peculiarities in the chapter of Zakat of Al-Sihah-al-Sithah

Rhetoric and Eloquence is the “Miracle of speech” The art of Rhetoric is aimed at the strong persuation and attractive oration.
 Like other realms, Religion needs to have prophetic Eloquence to persuade the receivers. The last Holy Prophet Hazrath Muhammad (SAW) had the sense of rhetorical speaking and often used to convince via eloquail strategies. 
 His Ahadees are regarded as landmarks so far artistic and eloquent speech is concerned.
 In this research Article, the researcher has tried to mark out some rhetorical aspects of his impressive oration especially with in the “kitabul Zakat” in al Sihah-al-Sithah. Keeping in view the Arabic classic and modern rhetoric embellishments, various utterances of Rasoolullah (SAW) are scrutinized rhetorically to show its eloquail peculiarity for benefit of Readers, listeners and researchers.

Performing pain: Sindhi Sufi music, affect, and Hindu-Muslim relations in western India

ABSTRACT This article examines the affective enactment of the Sufi emotional concept of the pain of separation by Muslim singers in Kachchh, Gujarat, a border region in western India adjacent to Sindh, Pakistan. In a discussion of two musical genres that feature the Sufi poetry of Shāh ‘Abdul Lat̤īf Bhiṭā’ī (1689–1752 CE) – kāfī and shāh jo rāg̈ – I argue that the musical performance of pain is ethically efficacious as well as politically salient. Drawing on eighteen months of fieldwork in Kachchh in 2014–2018, the article traces the ways in which poetry performers and enthusiasts conceive of musico-poetic pain as a form of Islamic worship that has ethical benefits for performers and listeners, such as tranquility and the purification of one’s heart. It thus demonstrates how Sindhi Sufi music functions as an affective, embodied, gendered and vernacular means of engagement with the Islamic discursive tradition. The latter portion of the article widens the focus, taking the pain of separation as a lens through which to examine Hindu-Muslim relations in Kachchh, where Hindu nationalism and Islamic reform have contributed to socio-religious polarisation since the 1980s. Drawing on examples from local musical history, I explore the political salience of the pain of separation by showing how the musical performance of Shāh Bhiṭā’ī’s female-voice poetry historically facilitated interreligious forms of male sociality in Kachchh.

Psychobiological Responses Reveal Audiovisual Noise Differentially Challenges Speech Recognition

In noisy environments, listeners benefit from both hearing and seeing a talker, demonstrating audiovisual (AV) cues enhance speech-in-noise (SIN) recognition. Here, we examined the relative contribution of auditory and visual cues to SIN perception and the strategies used by listeners to decipher speech in noise interference(s). Normal-hearing listeners (n = 22) performed an open-set speech recognition task while viewing audiovisual TIMIT sentences presented under different combinations of signal degradation including visual (AVn), audio (AnV), or multimodal (AnVn) noise. Acoustic and visual noises were matched in physical signal-to-noise ratio. Eyetracking monitored participants' gaze to different parts of a talker's face during SIN perception. As expected, behavioral performance for clean sentence recognition was better for A-only and AV compared to V-only speech. Similarly, with noise in the auditory channel (AnV and AnVn speech), performance was aided by the addition of visual cues of the talker regardless of whether the visual channel contained noise, confirming a multimodal benefit to SIN recognition. The addition of visual noise (AVn) obscuring the talker's face had little effect on speech recognition by itself. Listeners' eye gaze fixations were biased toward the eyes (decreased at the mouth) whenever the auditory channel was compromised. Fixating on the eyes was negatively associated with SIN recognition performance. Eye gazes on the mouth versus eyes of the face also depended on the gender of the talker. Collectively, results suggest listeners (1) depend heavily on the auditory over visual channel when seeing and hearing speech and (2) alter their visual strategy from viewing the mouth to viewing the eyes of a talker with signal degradations, which negatively affects speech perception.

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.

Individual Aided Speech-Recognition Performance and Predictions of Benefit for Listeners With Impaired Hearing Employing FADE.

The benefit in speech-recognition performance due to the compensation of a hearing loss can vary between listeners, even if unaided performance and hearing thresholds are similar. To accurately predict the individual performance benefit due to a specific hearing device, a prediction model is proposed which takes into account hearing thresholds and a frequency-dependent suprathreshold component of impaired hearing. To test the model, the German matrix sentence test was performed in unaided and individually aided conditions in quiet and in noise by 18 listeners with different degrees of hearing loss. The outcomes were predicted by an individualized automatic speech-recognition system where the individualization parameter for the suprathreshold component of hearing loss was inferred from tone-in-noise detection thresholds. The suprathreshold component was implemented as a frequency-dependent multiplicative noise (mimicking level uncertainty) in the feature-extraction stage of the automatic speech-recognition system. Its inclusion improved the root-mean-square prediction error of individual speech-recognition thresholds (SRTs) from 6.3 dB to 4.2 dB and of individual benefits in SRT due to common compensation strategies from 5.1 dB to 3.4 dB. The outcome predictions are highly correlated with both the corresponding observed SRTs (R2 = .94) and the benefits in SRT (R2 = .89) and hence might help to better understand—and eventually mitigate—the perceptual consequences of as yet unexplained hearing problems, also discussed in the context of hidden hearing loss.

The fluctuating masker benefit for normal-hearing and hearing-impaired listeners with equal audibility at a fixed signal-to-noise ratio.

Normal-hearing (NH) listeners can extract and integrate speech fragments from momentary dips in the level of a fluctuating masker, yielding a fluctuating-masker benefit (FMB) for speech understanding relative to a stationary-noise masker. Hearing-impaired (HI) listeners generally show less FMB, suggesting a dip-listening deficit attributable to suprathreshold spectral or temporal distortion. However, reduced FMB might instead result from different test signal-to-noise ratios (SNRs), reduced absolute audibility of otherwise unmasked speech segments, or age differences. This study examined the FMB for nine age-matched NH-HI listener pairs, while simultaneously equalizing audibility, SNR, and percentage-correct performance in stationary noise. Nonsense syllables were masked by stationary noise, 4- or 32-Hz sinusoidally amplitude-modulated noise (SAMN), or an opposite-gender interfering talker. Stationary-noise performance was equalized by adjusting the response-set size. Audibility was equalized by removing stimulus components falling below the HI absolute threshold. HI listeners showed a clear 4.5-dB reduction in FMB for 32-Hz SAMN, a similar FMB to NH listeners for 4-Hz SAMN, and a non-significant trend toward a 2-dB reduction in FMB for an interfering talker. These results suggest that HI listeners do not exhibit a general dip-listening deficit for all fluctuating maskers, but rather a specific temporal-resolution deficit affecting performance for high-rate modulated maskers.

Impact of room acoustic parameters on speech and music perception among participants with cochlear implants

ObjectivesBesides numerous other factors, listening experience with cochlear implants is substantially impaired by room acoustics. Even for persons without hearing impairment, the perception of auditory scenes, for example, concerning speech intelligibility, acoustic quality or audibility, is considerably influenced by room acoustics. For CI users, complex listening environments are usually associated with heavy losses.The aim of the present study was to determine room acoustic criteria that particularly influence speech pleasantness for CI users. DesignAccordingly, speech material of the Oldenburg Sentence Test (Oldenburger Satztest, OLSA) as well as basic music material (major and minor triads) were auralized using the software Auratorium which allows auralization of simulated rooms. The constructed rooms for speech stimuli were based on the standard DIN 18041:2016–03 concerning acoustic quality in rooms, the binding standard referred to by room acoustic consultants in Germany, which also includes specifications for inclusive applications in schools. For the music perception tests, two typical concert halls of different sizes were modelled. The auralized test stimuli were unilaterally presented to 10 CI users via their auxiliary input as well as to 18 participants with typical hearing via headphones (control group). Speech pleasantness was evaluated using modified MUSHRA tests. Concerning music perception, chord discrimination was tested using paired comparisons. ResultsA strong preference of small source to listener distances by CI users was found, but no significant preference for room acoustic attenuation which exceeded the recommended for inclusive applications in schools. The analyses of the energy-time-structures suggested that a dense concentration of early reflections makes a beneficial impact on CI listeners’ pleasantness ratings. Music materials were distinguished more consistently without any room acoustic impact, while any room acoustic impact led to performance close to chance level. This effect is probably due to spectral smearing effects caused by reverberation. ConclusionsThese results suggest that in terms of pleasantness of speech, for CI-users, source-to-listener distance is the more influential parameter than room attenuation which goes beyond the German standard recommendation. Reflections from which CI users can benefit seem to occur much earlier than those from which NH listeners benefit. Future studies on chord discrimination concerning room acoustics are needed.

Talker-familiarity benefit in non-native recognition memory and word identification: The role of listening conditions and proficiency.

Native listeners benefit from talker familiarity in recognition memory and word identification, especially in adverse listening conditions. The present study addresses the talker familiarity benefit in non-native listening, and the role of listening conditions and listeners' lexical proficiency in the emergence of this benefit. Dutch non-native listeners of English were trained to identify four English talkers over 4 days. Talker familiarity benefit in recognition memory was investigated using a recognition memory task with "old" and "new" words produced by familiar and unfamiliar talkers presented either in the clear or in noise. Talker familiarity benefit in word identification was investigated by comparing non-native listeners' performances on the first and the last day in identifying words in different noise levels, produced by either a trained (included in the voice recognition training) or by an untrained talker (not included in the voice recognition training). Non-native listeners demonstrated a talker familiarity benefit in recognition memory, which was modulated by listening conditions and proficiency in the non-native language. No talker familiarity benefit was found in word identification. These results suggest that, similar to native listening, both linguistic and indexical (talker-specific) information influence non-native speech perception. However, this is dependent on the task and type of speech recognition process involved.

Effects of age, modulation rate, and modulation depth on sentence recognition in speech-modulated noise

Speech is often heard in amplitude modulated backgrounds when speech is glimpsed during momentary masker dips. Increased masker modulation depth provides more improvement in the signal-to-noise ratio of glimpsed speech, but also improves noise modulation detection for potentially greater modulation masking. Mechanisms of modulation masking and glimpsing may also depend on the overlap of the modulation spectra of the speech and noise. This study employed modulation filtering and noise amplitude compression to investigate the combined effects of noise modulation depth and modulation rate on speech recognition. Younger normal-hearing (YNH), older normal-hearing (ONH), and older hearing-impaired (OHI) adults listened to sentences in noise that were spectrally shaped to control for individual hearing thresholds. A second YNH group listened to sentences with the same spectral shaping as OHI listeners. Sentence recognition generally improved with greater noise modulation depth, especially at higher modulation rates. Results suggest that speech recognition for all groups is maximized when speech modulations <8 Hz are preserved, when noise modulation occurs at rates higher than this range, and with greater noise modulation depth. OHI listeners benefit similarly from these conditions, but their poorer overall performance may be due to reduced sensation levels. [Work supported by NIH/NIDCD.]

Continued search for better prediction of aided speech understanding in multi-talker environments

To better understand issues of hearing-aid benefit during natural listening, this study examined the added demand placed by the goal of understanding speech over the more typically studied goal of simply recognizing speech sounds. The study compared hearing-aid benefit in two conditions, and examined factors that might account for the observed benefits. In the phonetic condition, listeners needed only identify the correct sound to make a correct response. In the semantic condition, listeners had to understand what they had heard to respond correctly, because the answer did not include any keywords from the spoken speech. Hearing aids provided significant benefit for listeners in the phonetic condition. In the semantic condition on the other hand, there were large inter-individual differences, with many listeners not experiencing any benefit of aiding. Neither a set of cognitive and linguistic tests, nor age, could explain this variability. Furthermore, analysis of psychometric functions showed that enhancement of the target speech fidelity through improvement of signal-to-noise ratio had a larger impact on listeners' performance in the phonetic condition than in the semantic condition. These results demonstrate the importance of incorporating naturalistic elements in the simulation of multi-talker listening for assessing the benefits of intervention in communication success.

The Effect of Interaural Mismatches on Contralateral Unmasking With Single-Sided Vocoders.

Cochlear-implant (CI) users with single-sided deafness (SSD)-that is, one normal-hearing (NH) ear and one CI ear-can obtain some unmasking benefits when a mixture of target and masking voices is presented to the NH ear and a copy of just the masking voices is presented to the CI ear. NH listeners show similar benefits in a simulation of SSD-CI listening, whereby a mixture of target and masking voices is presented to one ear and a vocoded copy of the masking voices is presented to the opposite ear. However, the magnitude of the benefit for SSD-CI listeners is highly variable across individuals and is on average less than for NH listeners presented with vocoded stimuli. One possible explanation for the limited benefit observed for some SSD-CI users is that temporal and spectral discrepancies between the acoustic and electric ears might interfere with contralateral unmasking. The present study presented vocoder simulations to NH participants to examine the effects of interaural temporal and spectral mismatches on contralateral unmasking. Speech-reception performance was measured in a competing-talker paradigm for NH listeners presented with vocoder simulations of SSD-CI listening. In the monaural condition, listeners identified target speech masked by two same-gender interferers, presented to the left ear. In the bilateral condition, the same stimuli were presented to the left ear, but the right ear was presented with a noise-vocoded copy of the interfering voices. This paradigm tested whether listeners could integrate the interfering voices across the ears to better hear the monaural target. Three common distortions inherent in CI processing were introduced to the vocoder processing: spectral shifts, temporal delays, and reduced frequency selectivity. In experiment 1, contralateral unmasking (i.e., the benefit from adding the vocoded maskers to the second ear) was impaired by spectral mismatches of four equivalent rectangular bandwidths or greater. This is equivalent to roughly a 3.6-mm mismatch between the cochlear places stimulated in the electric and acoustic ears, which is on the low end of the average expected mismatch for SSD-CI listeners. In experiment 2, performance was negatively affected by a temporal mismatch of 24 ms or greater, but not for mismatches in the 0 to 12 ms range expected for SSD-CI listeners. Experiment 3 showed an interaction between spectral shift and spectral resolution, with less effect of interaural spectral mismatches when the number of vocoder channels was reduced. Experiment 4 applied interaural spectral and temporal mismatches in combination. Performance was best when both frequency and timing were aligned, but in cases where a mismatch was present in one dimension (either frequency or latency), the addition of mismatch in the second dimension did not further disrupt performance. These results emphasize the need for interaural alignment-in timing and especially in frequency-to maximize contralateral unmasking for NH listeners presented with vocoder simulations of SSD-CI listening. Improved processing strategies that reduce mismatch between the electric and acoustic ears of SSD-CI listeners might improve their ability to obtain binaural benefits in multitalker environments.

Visual Context Enhanced: The Joint Contribution of Iconic Gestures and Visible Speech to Degraded Speech Comprehension

This study investigated whether and to what extent iconic co-speech gestures contribute to information from visible speech to enhance degraded speech comprehension at different levels of noise-vocoding. Previous studies of the contributions of these 2 visual articulators to speech comprehension have only been performed separately. Twenty participants watched videos of an actress uttering an action verb and completed a free-recall task. The videos were presented in 3 speech conditions (2-band noise-vocoding, 6-band noise-vocoding, clear), 3 multimodal conditions (speech + lips blurred, speech + visible speech, speech + visible speech + gesture), and 2 visual-only conditions (visible speech, visible speech + gesture). Accuracy levels were higher when both visual articulators were present compared with 1 or none. The enhancement effects of (a) visible speech, (b) gestural information on top of visible speech, and (c) both visible speech and iconic gestures were larger in 6-band than 2-band noise-vocoding or visual-only conditions. Gestural enhancement in 2-band noise-vocoding did not differ from gestural enhancement in visual-only conditions. When perceiving degraded speech in a visual context, listeners benefit more from having both visual articulators present compared with 1. This benefit was larger at 6-band than 2-band noise-vocoding, where listeners can benefit from both phonological cues from visible speech and semantic cues from iconic gestures to disambiguate speech.

What the [bleep]? Enhanced absolute pitch memory for a 1000 Hz sine tone

Many individuals are able to perceive when the tuning of familiar stimuli, such as popular music recordings, has been altered. This suggests a kind of ubiquitous pitch memory, though it is unclear how this ability differs across individuals with and without absolute pitch (AP) and whether it plays any role in AP. In the present study, we take advantage of a salient single frequency – the 1000Hz sine tone used to censor taboo words in broadcast media – to assess the nature of this kind of pitch memory across individuals with and without AP. We show that non-AP participants are accurate at selecting the correct version of the censor tone among incorrect versions shifted by either one or two semitones, though their accuracy was still below that of an AP population (Experiment 1). This suggests a benefit for AP listeners that could be due to the use of explicit note categories or greater amounts of musical training. However, AP possessors still outperformed all non-AP participants when incorrect versions of the censor tone were shifted within a note category, even when controlling for musical experience (Experiment 2). Experiment 3 demonstrated that AP listeners did not appear to possess a category label for the censor tone that could have helped them differentiate the censor tones used in Experiment 2. Overall, these results suggest that AP possessors may have better pitch memory, even when divorced from pitch labeling (note categories). As such, these results have implications for how AP may develop and be maintained.

Effects of a consistent target or masker voice on target speech intelligibility in two- and three-talker mixtures.

When the spatial location or identity of a sound is held constant, it is not masked as effectively by competing sounds. This suggests that experience with a particular voice over time might facilitate perceptual organization in multitalker environments. The current study examines whether listeners benefit from experience with a voice only when it is the target, or also when it is a masker, using diotic presentation and a closed-set task (coordinate response measure). A reliable interaction was observed such that, in two-talker mixtures, consistency of masker or target voice over 3-7 trials significantly benefited target recognition performance, whereas in three-talker mixtures, target, but not masker, consistency was beneficial. Overall, this work suggests that voice consistency improves intelligibility, although somewhat differently when two talkers, compared to three talkers, are present, suggesting that consistent-voice information facilitates intelligibility in at least two different ways. Listeners can use a template-matching strategy to extract a known voice from a mixture when it is the target. However, consistent-voice information facilitates segregation only when two, but not three, talkers are present.

Effects of Reverberation on Sound Localization for Bilateral Cochlear Implant Users

The purpose of this study was to examine the effects of reverberation on the ability of listeners with bilateral cochlear implants (BCIs) to localize speech in anechoic and reverberant environments. Two specific research questions were addressed: (1) how do listeners with BCIs localize sounds in different environments compared to listeners with normal hearing (NH)? and (2) at what reverberation time (RT60) does localization performance begin to decline for both groups of subjects? Six adults with BCIs and ten with NH participated. All subjects completed a virtual localization test in simulated anechoic and reverberant environments (0.0, 0.2, 0.6, and 0.9 s RT60) in quiet. A three-word phrase was presented at 70 dBSPL from nine simulated source locations in the frontal-horizontal plane (± 900). Root-mean-square localization error (RMSLE) in degrees was calculated. Results revealed localization accuracy significantly decreased as reverberation time increased for both groups of subjects. Listeners with BCIs had significantly poorer localization accuracy than listeners with NH in all conditions. Their RMSLE changed from 320 in anechoic condition to 600 in RT60 0.9s condition, while corresponding change for listeners with NH was only from 170 to 220. In addition, localization performance of listeners with BCIs started to decrease at a shorter reverberation time (RT60 0.6s) compared to those with NH (RT60 0.9s). In conclusion, reverberation significantly degraded localization performance, with a greater influence on listeners with BCIs than listeners with NH. In addition, bilateral experience is likely to help listeners with BCIs achieve a better localization outcome over time. It is important to apply the information obtained in this study to optimize binaural benefit for listeners with BCIs in everyday listening situations.

Channel Interaction and Current Level Affect Across-Electrode Integration of Interaural Time Differences in Bilateral Cochlear-Implant Listeners.

Sensitivity to interaural time differences (ITDs) is important for sound localization. Normal-hearing listeners benefit from across-frequency processing, as seen with improved ITD thresholds when consistent ITD cues are presented over a range of frequency channels compared with when ITD information is only presented in a single frequency channel. This study aimed to clarify whether cochlear-implant (CI) listeners can make use of similar processing when being stimulated with multiple interaural electrode pairs transmitting consistent ITD information. ITD thresholds for unmodulated, 100-pulse-per-second pulse trains were measured in seven bilateral CI listeners using research interfaces. Consistent ITDs were presented at either one or two electrode pairs at different current levels, allowing for comparisons at either constant level per component electrode or equal overall loudness. Different tonotopic distances between the pairs were tested in order to clarify the potential influence of channel interaction. Comparison of ITD thresholds between double pairs and the respective single pairs revealed systematic effects of tonotopic separation and current level. At constant levels, performance with double-pair stimulation improved compared with single-pair stimulation but only for large tonotopic separation. Comparisons at equal overall loudness revealed no benefit from presenting ITD information at two electrode pairs for any tonotopic spacing. Irrespective of electrode-pair configuration, ITD sensitivity improved with increasing current level. Hence, the improved ITD sensitivity for double pairs found for a large tonotopic separation and constant current levels seems to be due to increased loudness. The overall data suggest that CI listeners can benefit from combining consistent ITD information across multiple electrodes, provided sufficient stimulus levels and that stimulating electrode pairs are widely spaced.

The effect of semantic cues on intelligibility: A comparison between spectrally sparse speech and natural speech in noise

Listeners are known to make use of contextual cues when perceiving speech. Using contextual information is even more important when listening to distorted or difficult speech signals. For example, listeners benefit from contextual cues to compensate for the absence of fine acoustic-phonetic information when listening to natural speech in noise. In the present investigation, the effect of context was compared between four- and eight-channel spectrally degraded speech (Shannon et al., 1995) versus natural speech-in-noise (0 dB SNR). Spectrally degraded speech simulates the primary information transmitted by cochlear implant devices. The results demonstrated that eight-band signals received benefit from context to the same extent as natural speech in noise. In contrast, four-band signals provided significantly less benefit from context than natural speech in noise. The most parsimonious explanation of this pattern of results is that listeners need a threshold amount of acoustic information to make use of context equally, regardless of the type of distortion. Alternatively, the results could be explained by assuming that listeners employ different strategies depending on the overall acoustic characteristics of the speech signal. Future experiments will distinguish between these alternatives.