Cortical Regions Activated by Spectrally Degraded Speech in Adults With Single Sided Deafness or Bilateral Normal Hearing.
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SUBMITTER: Burton H
PROVIDER: S-EPMC8058229 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:IntroductionCochlear implants (CIs) are the treatment of choice for severe to profound hearing loss. Variability in CI outcomes remains despite advances in technology and is attributed in part to differences in cortical processing. Studying these differences in CI users is technically challenging. Spectrally degraded stimuli presented to normal-hearing individuals approximate input to the central auditory system in CI users. This study used intracranial electroencephalography (iEEG) to investigate cortical processing of spectrally degraded speech.MethodsParticipants were adult neurosurgical epilepsy patients. Stimuli were utterances /aba/ and /ada/, spectrally degraded using a noise vocoder (1-4 bands) or presented without vocoding. The stimuli were presented in a two-alternative forced choice task. Cortical activity was recorded using depth and subdural iEEG electrodes. Electrode coverage included auditory core in posteromedial Heschl's gyrus (HGPM), superior temporal gyrus (STG), ventral and dorsal auditory-related areas, and prefrontal and sensorimotor cortex. Analysis focused on high gamma (70-150 Hz) power augmentation and alpha (8-14 Hz) suppression.ResultsChance task performance occurred with 1-2 spectral bands and was near-ceiling for clear stimuli. Performance was variable with 3-4 bands, permitting identification of good and poor performers. There was no relationship between task performance and participants demographic, audiometric, neuropsychological, or clinical profiles. Several response patterns were identified based on magnitude and differences between stimulus conditions. HGPM responded strongly to all stimuli. A preference for clear speech emerged within non-core auditory cortex. Good performers typically had strong responses to all stimuli along the dorsal stream, including posterior STG, supramarginal, and precentral gyrus; a minority of sites in STG and supramarginal gyrus had a preference for vocoded stimuli. In poor performers, responses were typically restricted to clear speech. Alpha suppression was more pronounced in good performers. In contrast, poor performers exhibited a greater involvement of posterior middle temporal gyrus when listening to clear speech.DiscussionResponses to noise-vocoded speech provide insights into potential factors underlying CI outcome variability. The results emphasize differences in the balance of neural processing along the dorsal and ventral stream between good and poor performers, identify specific cortical regions that may have diagnostic and prognostic utility, and suggest potential targets for neuromodulation-based CI rehabilitation strategies.
| S-EPMC10839784 | biostudies-literature
Project description:Cochlear implants provide good speech discrimination ability despite highly limited amount of information they transmit compared with normal cochlea. Noise vocoded speech, simulating cochlear implants in normal hearing listeners, have demonstrated that spectrally and temporally degraded speech contains sufficient cues to provide accurate speech discrimination. We hypothesized that neural activity patterns generated in the primary auditory cortex by spectrally and temporally degraded speech sounds will account for the robust behavioral discrimination of speech. We examined the behavioral discrimination of noise vocoded consonants and vowels by rats and recorded neural activity patterns from rat primary auditory cortex (A1) for the same sounds. We report the first evidence of behavioral discrimination of degraded speech sounds by an animal model. Our results show that rats are able to accurately discriminate both consonant and vowel sounds even after significant spectral and temporal degradation. The degree of degradation that rats can tolerate is comparable to human listeners. We observed that neural discrimination based on spatiotemporal patterns (spike timing) of A1 neurons is highly correlated with behavioral discrimination of consonants and that neural discrimination based on spatial activity patterns (spike count) of A1 neurons is highly correlated with behavioral discrimination of vowels. The results of the current study indicate that speech discrimination is resistant to degradation as long as the degraded sounds generate distinct patterns of neural activity.
| S-EPMC3387312 | biostudies-literature
Project description:Understanding cortical processing of spectrally degraded speech in normal-hearing subjects may provide insights into how sound information is processed by cochlear implant (CI) users. This study investigated electrocorticographic (ECoG) responses to noise-vocoded speech and related these responses to behavioral performance in a phonemic identification task. Subjects were neurosurgical patients undergoing chronic invasive monitoring for medically refractory epilepsy. Stimuli were utterances /aba/ and /ada/, spectrally degraded using a noise vocoder (1-4 bands). ECoG responses were obtained from Heschl's gyrus (HG) and superior temporal gyrus (STG), and were examined within the high gamma frequency range (70-150 Hz). All subjects performed at chance accuracy with speech degraded to 1 and 2 spectral bands, and at or near ceiling for clear speech. Inter-subject variability was observed in the 3- and 4-band conditions. High gamma responses in posteromedial HG (auditory core cortex) were similar for all vocoded conditions and clear speech. A progressive preference for clear speech emerged in anterolateral segments of HG, regardless of behavioral performance. On the lateral STG, responses to all vocoded stimuli were larger in subjects with better task performance. In contrast, both behavioral and neural responses to clear speech were comparable across subjects regardless of their ability to identify degraded stimuli. Findings highlight differences in representation of spectrally degraded speech across cortical areas and their relationship to perception. The results are in agreement with prior non-invasive results. The data provide insight into the neural mechanisms associated with variability in perception of degraded speech and potentially into sources of such variability in CI users.
| S-EPMC6309487 | biostudies-literature
Project description:The measurement of pupil dilation has become a common way to assess listening effort. Pupillometry data are subject to artifacts, requiring highly contaminated data to be discarded from analysis. It is unknown how trial exclusion criteria impact experimental results. The present study examined the effect of a common exclusion criterion, percentage of blinks, on speech intelligibility and pupil dilation measures in 9 participants with single-sided deafness (SSD) and 20 participants with normal hearing. Participants listened to and repeated sentences in quiet or with speech maskers. Pupillometry trials were processed using three levels of blink exclusion criteria: 15%, 30%, and 45%. These percentages reflect a threshold for missing data points in a trial, where trials that exceed the threshold are excluded from analysis. Results indicated that pupil dilation was significantly greater and intelligibility was significantly lower in the masker compared with the quiet condition for both groups. Across-group comparisons revealed that speech intelligibility in the SSD group decreased significantly more than the normal hearing group from quiet to masker conditions, but the change in pupil dilation was similar for both groups. There was no effect of blink criteria on speech intelligibility or pupil dilation results for either group. However, the total percentage of blinks in the masker condition was significantly greater than in the quiet condition for the SSD group, which is consistent with previous studies that have found a relationship between blinking and task difficulty. This association should be carefully considered in future experiments using pupillometry to gauge listening effort.
| S-EPMC8150669 | biostudies-literature
Project description:OBJECTIVES:Visual information from talkers facilitates speech intelligibility for listeners when audibility is challenged by environmental noise and hearing loss. Less is known about how listeners actively process and attend to visual information from different talkers in complex multi-talker environments. This study tracked looking behavior in children with normal hearing (NH), mild bilateral hearing loss (MBHL), and unilateral hearing loss (UHL) in a complex multi-talker environment to examine the extent to which children look at talkers and whether looking patterns relate to performance on a speech-understanding task. It was hypothesized that performance would decrease as perceptual complexity increased and that children with hearing loss would perform more poorly than their peers with NH. Children with MBHL or UHL were expected to demonstrate greater attention to individual talkers during multi-talker exchanges, indicating that they were more likely to attempt to use visual information from talkers to assist in speech understanding in adverse acoustics. It also was of interest to examine whether MBHL, versus UHL, would differentially affect performance and looking behavior. DESIGN:Eighteen children with NH, eight children with MBHL, and 10 children with UHL participated (8-12 years). They followed audiovisual instructions for placing objects on a mat under three conditions: a single talker providing instructions via a video monitor, four possible talkers alternately providing instructions on separate monitors in front of the listener, and the same four talkers providing both target and nontarget information. Multi-talker background noise was presented at a 5 dB signal-to-noise ratio during testing. An eye tracker monitored looking behavior while children performed the experimental task. RESULTS:Behavioral task performance was higher for children with NH than for either group of children with hearing loss. There were no differences in performance between children with UHL and children with MBHL. Eye-tracker analysis revealed that children with NH looked more at the screens overall than did children with MBHL or UHL, though individual differences were greater in the groups with hearing loss. Listeners in all groups spent a small proportion of time looking at relevant screens as talkers spoke. Although looking was distributed across all screens, there was a bias toward the right side of the display. There was no relationship between overall looking behavior and performance on the task. CONCLUSIONS:The present study examined the processing of audiovisual speech in the context of a naturalistic task. Results demonstrated that children distributed their looking to a variety of sources during the task, but that children with NH were more likely to look at screens than were those with MBHL/UHL. However, all groups looked at the relevant talkers as they were speaking only a small proportion of the time. Despite variability in looking behavior, listeners were able to follow the audiovisual instructions and children with NH demonstrated better performance than children with MBHL/UHL. These results suggest that performance on some challenging multi-talker audiovisual tasks is not dependent on visual fixation to relevant talkers for children with NH or with MBHL/UHL.
| S-EPMC6003828 | biostudies-literature
Project description:BackgroundAdults with single sided deafness (SSD) have lost binaural function, which limits sound source localization, speech understanding in noise, and quality of life. For SSD patients, restoration of bilateral auditory input is possible only with a cochlear implant (CI). In this study, cortical auditory evoked potentials (CAEPs) and behavioral performance were measured in left-implanted (SSD-CI-L) and right-implanted (SSD-CI-R) patients before and after cochlear implantation. We hypothesized that improvements in behavioral performance would be accompanied by changes in CAEPs after cochlear implantation.DesignProspective longitudinal study.SettingTertiary referral center.MethodNine right-handed adult SSD CI patients participated in the study. CAEPs were recorded before cochlear implantation and at 6 and 12 months post-implantation. CAEPs were elicited using speech stimuli (/ba/) delivered in sound field at 70 dBA. Global field power (GFP) latency and amplitude were calculated for P1, N1 and P2 peaks at each test session. CAEP were analyzed at frontocentral (Cz) and temporal (P7, P8, T7 and T8) and mastoid electrodes (M1 and M2) contralateral to the CI ear. Behavioral measures (sentence recognition in noise, with and without spatial cues) were collected at the same test sessions as for CAEPs. Speech performance and CAEPs were also measured in a control group of normal-hearing (NH) subjects.ResultsWhile increased N1 amplitude was observed in the scalp potential maps for GFP and Cz for SSD-CI-L patients after implantation, the changes were not statistically significant. Peak CAEP amplitude at electrodes to contralateral to the CI ear increased after cochlear implantation for all SSD-CI patients, but significant increases were observed only for mastoid sites. Peak latencies for some components at temporal and mastoid sites remained significantly longer than for the NH control group, even after cochlear implantation. For SSD-CI-R patients, P2 peak amplitude for baseline GFP and Cz was significantly lower than for the NH control group. A significant improvement for speech understanding in noise was observed at 12 months post-implantation when speech was presented to the CI ear and noise to the non-implanted ear.ConclusionAfter cochlear implantation, speech understanding significantly improved when speech and noise were spatially separated. The increased N1 amplitude for SSD-CI-L patients and the increased bilateral activation for all SSD-CI patients may reflect cortical reorganization and restoration of binaural function after one year of experience with the CI. However, because of the limited number of SSD patients, significant changes in cortical activity after cochlear implantation were often difficult to observe.
| S-EPMC6152998 | biostudies-literature
Project description:ObjectivesNormally-hearing (NH) listeners rely more on prosodic cues than on lexical-semantic cues for emotion perception in speech. In everyday spoken communication, the ability to decipher conflicting information between prosodic and lexical-semantic cues to emotion can be important: for example, in identifying sarcasm or irony. Speech degradation in cochlear implants (CIs) can be sufficiently overcome to identify lexical-semantic cues, but the distortion of voice pitch cues makes it particularly challenging to hear prosody with CIs. The purpose of this study was to examine changes in relative reliance on prosodic and lexical-semantic cues in NH adults listening to spectrally degraded speech and adult CI users. We hypothesized that, compared with NH counterparts, CI users would show increased reliance on lexical-semantic cues and reduced reliance on prosodic cues for emotion perception. We predicted that NH listeners would show a similar pattern when listening to CI-simulated versions of emotional speech.DesignSixteen NH adults and 8 postlingually deafened adult CI users participated in the study. Sentences were created to convey five lexical-semantic emotions (angry, happy, neutral, sad, and scared), with five sentences expressing each category of emotion. Each of these 25 sentences was then recorded with the 5 (angry, happy, neutral, sad, and scared) prosodic emotions by 2 adult female talkers. The resulting stimulus set included 125 recordings (25 Sentences × 5 Prosodic Emotions) per talker, of which 25 were congruent (consistent lexical-semantic and prosodic cues to emotion) and the remaining 100 were incongruent (conflicting lexical-semantic and prosodic cues to emotion). The recordings were processed to have 3 levels of spectral degradation: full-spectrum, CI-simulated (noise-vocoded) to have 8 channels and 16 channels of spectral information, respectively. Twenty-five recordings (one sentence per lexical-semantic emotion recorded in all five prosodies) were used for a practice run in the full-spectrum condition. The remaining 100 recordings were used as test stimuli. For each talker and condition of spectral degradation, listeners indicated the emotion associated with each recording in a single-interval, five-alternative forced-choice task. The responses were scored as proportion correct, where "correct" responses corresponded to the lexical-semantic emotion. CI users heard only the full-spectrum condition.ResultsThe results showed a significant interaction between hearing status (NH, CI) and congruency in identifying the lexical-semantic emotion associated with the stimuli. This interaction was as predicted, that is, CI users showed increased reliance on lexical-semantic cues in the incongruent conditions, while NH listeners showed increased reliance on the prosodic cues in the incongruent conditions. As predicted, NH listeners showed increased reliance on lexical-semantic cues to emotion when the stimuli were spectrally degraded.ConclusionsThe present study confirmed previous findings of prosodic dominance for emotion perception by NH listeners in the full-spectrum condition. Further, novel findings with CI patients and NH listeners in the CI-simulated conditions showed reduced reliance on prosodic cues and increased reliance on lexical-semantic cues to emotion. These results have implications for CI listeners' ability to perceive conflicts between prosodic and lexical-semantic cues, with repercussions for their identification of sarcasm and humor. Understanding instances of sarcasm or humor can impact a person's ability to develop relationships, follow conversation, understand vocal emotion and intended message of a speaker, following jokes, and everyday communication in general.
| S-EPMC8545870 | biostudies-literature
Project description:PurposeThis study investigated neuroplastic changes induced by postlingual single-sided deafness (SSD) and the effects of a cochlear implantation for the deaf ear. Neural processing of acoustic signals from the normal hearing ear to the brain was studied before and after implantation using a positron emission tomography (PET)/CT scanner.MethodsEight patients with postlingual SSD received a cochlear implant (CI) in a prospective clinical trial. Dynamic imaging was performed in a PET/CT scanner using radioactively labeled water ([15O]H2O) to localize changes in the regional cerebral blood flow (rCBF) with and without an auditory task of logatomes containing speech-like elements without meaningful context. The normal hearing ear was stimulated before implantation and after the use of the cochlear implant for at least 8 months (mean 13.5, range 8.1-26.6). Eight age- and gender-matched subjects with normal hearing on both sides served as healthy control subjects (HCS).ResultsWhen the normal hearing ear of SSD patients was stimulated before CI implantation, the [15O]H2O-PET showed a more symmetrical rCBF in the auditory regions of both hemispheres in comparison to the HCS. The use of CI increased the asymmetry index (AI) in six of eight patients indicating an increase of activity of the contralateral hemisphere. Non-parametric statistics revealed a significant difference in the AI between patients before CI implantation and HCS (p < .01), which disappeared after CI implantation (p = .195).ConclusionThe functional neuroimaging data showed a tendency towards normalization of neuronal activity after CI implantation, which supports the effectiveness of CI in SSD patients.Trial registrationClinicalTrials.gov Identifier: NCT01749592, December 13, 2012.
| S-EPMC10907329 | biostudies-literature
Project description:BACKGROUND:Cochlear implantation for single-sided deafness (SSD) is the only treatment option with the potential to restore binaural hearing cues. Significant binaural benefit has been measured in adults by speech in noise and localisation tests, who receive a cochlear implant for SSD, however, little is known on the cortical changes that help provide this benefit. In the present study, detection of sound in the auditory cortex, speech testing and localisation was used to investigate the ability of a cochlear implant (CI) to restore auditory cortical latencies and improve binaural benefit in the adult SSD population. METHODS:Twenty-nine adults with acquired single-sided deafness who received a CI in adulthood were studied. Speech perception in noise was tested using the Bamford-Kowal-Bench speech-in-noise test, localisation ability was measured using the auditory speech sounds evaluation (AδE) localisation test and cortical auditory evoked responses, comparing N1-P2 latencies recorded from the normal hearing ear and cochlear implant were used to investigate the synchrony of the cortical pathway from the CI and normal hearing ear (NHe) with binaural hearing function. RESULTS:There was a significant improvement in speech perception in noise in all spatial configurations S0/N0 (Z = -3.066, p<0.002), S0/NHE (Z = -4.031, p<0.001), SCI/NHE (Z = -3.851, p<0.001). Localization significantly improved when tested with the cochlear implant on (p<0.001) with a shorter duration of deafness correlating to a greater improvement in localisation ability F(1:18) = 6.854; p = 0.017). There was no significant difference in N1-P2 latency recorded from the normal hearing ear and the CI. CONCLUSION:Cortical auditory evoked response latencies recorded from the CI and NHe showed no significant difference, indicating that the detection of sound in the auditory cortex occurred simultaneously, providing the cortex with auditory information for binaural hearing.
| S-EPMC6959557 | biostudies-literature
Project description:BackgroundThis systematic review aimed to identify, compare and contrast outcome domains and outcome instruments reported in studies investigating interventions that seek to restore bilateral (two-sided) and/or binaural (both ears) hearing in adults with single-sided deafness (SSD). Findings can inform the development of evidence-based guidance to facilitate design decisions for confirmatory trials.MethodsRecords were identified by searching MEDLINE, EMBASE, PubMed, CINAHL, ClinicalTrials.gov, ISRCTN, CENTRAL, WHO ICTRP and the NIHR UK clinical trials gateway. The search included records published from 1946 to March 2020. Included studies were those as follows: (a) recruiting adults aged 18 years or older diagnosed with SSD of average threshold severity worse than 70 dB HL in the worse-hearing ear and normal (or near-normal) hearing in the better-hearing ear, (b) evaluating interventions to restore bilateral and/or binaural hearing and (c) enrolling those adults in a controlled trial, before-and-after study or cross-over study. Studies that fell just short of the participant eligibility criteria were included in a separate sensitivity analysis.ResultsNinety-six studies were included (72 full inclusion, 24 sensitivity analysis). For fully included studies, 37 exclusively evaluated interventions to re-establish bilateral hearing and 29 exclusively evaluated interventions to restore binaural hearing. Overall, 520 outcome domains were identified (350 primary and 170 secondary). Speech-related outcome domains were the most common (74% of studies), followed by spatial-related domains (60% of studies). A total of 344 unique outcome instruments were reported. Speech-related outcome domains were measured by 73 different instruments and spatial-related domains by 43 different instruments. There was considerable variability in duration of follow-up, ranging from acute (baseline) testing to 10 years after the intervention. The sensitivity analysis identified no additional outcome domains.ConclusionsThis review identified large variability in the reporting of outcome domains and instruments in studies evaluating the therapeutic benefits and harms of SSD interventions. Reports frequently omitted information on what domains the study intended to assess, and on what instruments were used to measure which domains.Trial registrationThe systematic review protocol is registered on PROSPERO (International Prospective Register of Systematic Reviews): Registration Number CRD42018084274 . Registered on 13 March 2018, last revised on 7th of May 2019.
| S-EPMC7981927 | biostudies-literature