Frequency detection, frequency discrimination, and spectro-temporal pattern perception in older and younger typically hearing adults.

Elderly adults often experience difficulties in speech understanding, possibly due to age-related deficits in frequency perception. It is unclear whether age-related deficits in frequency perception differ between the apical or basal regions of the cochlea. It is also unclear how aging might differently affect frequency discrimination or detection of a change in frequency within a stimulus. In the present study, pure-tone frequency thresholds were measured in 19 older (61-74 years) and 20 younger (22-28 years) typically hearing adults. Participants were asked to discriminate between reference and probe frequencies or to detect changes in frequency within a probe stimulus. Broadband spectro-temporal pattern perception was also measured using the spectro-temporal modulated ripple test (SMRT). Frequency thresholds were significantly poorer in the basal than in the apical region of the cochlea; the deficit in the basal region was 2 times larger for the older than for the younger group. Frequency thresholds were significantly poorer in the older group, especially in the basal region where frequency detection thresholds were 3.9 times poorer for the older than for the younger group. SMRT thresholds were 1.5 times better for the younger than for the older group. Significant age effects were observed for SMRT thresholds and for frequency thresholds only in the basal region. SMRT thresholds were significantly correlated with frequency thresholds only in the older group. The poorer frequency and spectro-temporal pattern perception may contribute to age-related deficits in speech perception, even when audiometric thresholds are nearly normal.

Acoustic analysis of tone production in Mandarin-speaking bimodal cochlear implant users.

The benefit of using a hearing aid with a cochlear implant (bimodal hearing) has been demonstrated for tone perception under certain conditions. The present study evaluated bimodal effects for tone production by comparing performance between a bimodal and a unimodal implant group. Results showed that acoustic differentiation of tones produced by the bimodal group was better than the unimodal implant group, and performance was dependent on the subject's acoustic thresholds but not related to implant experience or age at implantation. The findings support the use of amplified acoustic hearing in conjunction with the implant for better development of pitch production.

The P300 Auditory Event-Related Potential May Predict Segregation of Competing Speech by Bimodal Cochlear Implant Listeners.

Compared to normal-hearing (NH) listeners, cochlear implant (CI) listeners have greater difficulty segregating competing speech. Neurophysiological studies have largely investigated the neural foundations for CI listeners' speech recognition in quiet, mainly using the P300 component of event-related potentials (ERPs). P300 is closely related to cognitive processes involving auditory discrimination, selective attention, and working memory. Different from speech perception in quiet, little is known about the neurophysiological foundations for segregation of competing speech by CI listeners. In this study, ERPs were measured for a 1 vs. 2 kHz contrast in 11 Mandarin-speaking bimodal CI listeners and 11 NH listeners. Speech reception thresholds (SRTs) for a male target talker were measured in steady noise or with a male or female masker. Results showed that P300 amplitudes were significantly larger and latencies were significantly shorter for the NH than for the CI group. Similarly, SRTs were significantly better for the NH than for the CI group. Across all participants, P300 amplitude was significantly correlated with SRTs in steady noise (r = -0.65, p = 0.001) and with the competing male (r = -0.62, p = 0.002) and female maskers (r = -0.60, p = 0.003). Within the CI group, there was a significant correlation between P300 amplitude and SRTs with the male masker (r = -0.78, p = 0.005), which produced the most informational masking. The results suggest that P300 amplitude may be a clinically useful neural correlate of central auditory processing capabilities (e.g., susceptibility to informational masking) in bimodal CI patients.

Effect of Ipsilateral, Contralateral or Bilateral Repetitive Transcranial Magnetic Stimulation in Patients with Lateralized Tinnitus: A Placebo-Controlled Randomized Study.

The relative benefit of ipsilateral, contralateral, and bilateral repetitive transcranial magnetic stimulation (rTMS) for tinnitus treatment remains unclear, especially for patients with lateralized tinnitus. In this study, we compared outcomes after 10 sessions of 1-Hz rTMS at 110% of resting motor threshold over a two-week period. In total, 104 right-handed patients with lateralized subjective tinnitus were randomly divided into four groups according to rTMS treatment: Left (n = 29), Right (n = 23), Bilateral (n = 30), and Sham stimulation (n = 22). Outcomes included estimates of tinnitus severity, psychological state, and psychoacoustic measures. Patients with left- or right-sided tinnitus were similarly distributed across treatment groups. There were no significant changes in outcome measures for the Right or Sham treatment groups. For the Left and Bilateral groups, tinnitus severity was significantly lower after treatment (p < 0.05). The reduction in tinnitus severity was largest for ipsilateral treatment in the Left group. The overall response rate was 56.1% for the Left group, 46.7% for the Bilateral group, 8.3% for the Right group, and 8.3% for the Sham group. For the Left and Bilateral groups, the response rate was larger for patients with left- than right-sided tinnitus. Changes in tinnitus severity were best predicted by changes in anxiety, depression, and the loudness of the tinnitus. The results suggests that rTMS on the left temporoparietal cortex is more effective for patients with left-sided than with right-sided tinnitus.

Segregation of competing speech in adults and children with normal hearing and in children with cochlear implants.

Children with normal hearing (CNH) have greater difficulty segregating competing speech than do adults with normal hearing (ANH). Children with cochlear implants (CCI) have greater difficulty segregating competing speech than do CNH. In the present study, speech reception thresholds (SRTs) in competing speech were measured in Chinese Mandarin-speaking ANH, CNH, and CCIs. Target sentences were produced by a male Mandarin-speaking talker. Maskers were time-forward or -reversed sentences produced by a native Mandarin-speaking male (different from the target) or female or a non-native English-speaking male. The SRTs were lowest (best) for the ANH group, followed by the CNH and CCI groups. The masking release (MR) was comparable between the ANH and CNH group, but much poorer in the CCI group. The temporal properties differed between the native and non-native maskers and between forward and reversed speech. The temporal properties of the maskers were significantly associated with the SRTs for the CCI and CNH groups but not for the ANH group. Whereas the temporal properties of the maskers were significantly associated with the MR for all three groups, the association was stronger for the CCI and CNH groups than for the ANH group.

Effects of Monaural Asymmetry and Target-Masker Similarity on Binaural Advantage in Children and Adults With Normal Hearing.

Purpose For colocated targets and maskers, binaural listening typically offers a small but significant advantage over monaural listening. This study investigated how monaural asymmetry and target-masker similarity may limit binaural advantage in adults and children. Method Ten Mandarin-speaking Chinese adults (aged 22-27 years) and 12 children (aged 7-14 years) with normal hearing participated in the study. Monaural and binaural speech recognition thresholds (SRTs) were adaptively measured for colocated competing speech. The target-masker sex was the same or different. Performance was measured using headphones for three listening conditions: left ear, right ear, and both ears. Binaural advantage was calculated relative to the poorer or better ear. Results Mean SRTs were significantly lower for adults than children. When the target-masker sex was the same, SRTs were significantly lower with the better ear than with the poorer ear or both ears (p < .05). When the target-masker sex was different, SRTs were significantly lower with the better ear or both ears than with the poorer ear (p < .05). Children and adults similarly benefitted from target-masker sex differences. Substantial monaural asymmetry was observed, but the effects of asymmetry on binaural advantage were similar between adults and children. Monaural asymmetry was significantly correlated with binaural advantage relative to the poorer ear (p = .004), but not to the better ear (p = .056). Conclusions Binaural listening may offer little advantage (or even a disadvantage) over monaural listening with the better ear, especially when competing talkers have similar vocal characteristics. Monaural asymmetry appears to limit binaural advantage in listeners with normal hearing, similar to observations in listeners with hearing impairment. While language development may limit perception of competing speech, it does not appear to limit the effects of monaural asymmetry or target-masker sex on binaural advantage.

Factors Affecting Bimodal Benefit in Pediatric Mandarin-Speaking Chinese Cochlear Implant Users.

OBJECTIVES: While fundamental frequency (F0) cues are important to both lexical tone perception and multitalker segregation, F0 cues are poorly perceived by cochlear implant (CI) users. Adding low-frequency acoustic hearing via a hearing aid in the contralateral ear may improve CI users' F0 perception. For English-speaking CI users, contralateral acoustic hearing has been shown to improve perception of target speech in noise and in competing talkers. For tonal languages such as Mandarin Chinese, F0 information is lexically meaningful. Given competing F0 information from multiple talkers and lexical tones, contralateral acoustic hearing may be especially beneficial for Mandarin-speaking CI users' perception of competing speech. DESIGN: Bimodal benefit (CI+hearing aid - CI-only) was evaluated in 11 pediatric Mandarin-speaking Chinese CI users. In experiment 1, speech recognition thresholds (SRTs) were adaptively measured using a modified coordinated response measure test; subjects were required to correctly identify 2 keywords from among 10 choices in each category. SRTs were measured with CI-only or bimodal listening in the presence of steady state noise (SSN) or competing speech with the same (M+M) or different voice gender (M+F). Unaided thresholds in the non-CI ear and demographic factors were compared with speech performance. In experiment 2, SRTs were adaptively measured in SSN for recognition of 5 keywords, a more difficult listening task than the 2-keyword recognition task in experiment 1. RESULTS: In experiment 1, SRTs were significantly lower for SSN than for competing speech in both the CI-only and bimodal listening conditions. There was no significant difference between CI-only and bimodal listening for SSN and M+F (p > 0.05); SRTs were significantly lower for CI-only than for bimodal listening for M+M (p < 0.05), suggesting bimodal interference. Subjects were able to make use of voice gender differences for bimodal listening (p < 0.05) but not for CI-only listening (p > 0.05). Unaided thresholds in the non-CI ear were positively correlated with bimodal SRTs for M+M (p < 0.006) but not for SSN or M+F. No significant correlations were observed between any demographic variables and SRTs (p > 0.05 in all cases). In experiment 2, SRTs were significantly lower with two than with five keywords (p < 0.05). A significant bimodal benefit was observed only for the 5-keyword condition (p < 0.05). CONCLUSIONS: With the CI alone, subjects experienced greater interference with competing speech than with SSN and were unable to use voice gender difference to segregate talkers. For the coordinated response measure task, subjects experienced no bimodal benefit and even bimodal interference when competing talkers were the same voice gender. A bimodal benefit in SSN was observed for the five-keyword condition but not for the two-keyword condition, suggesting that bimodal listening may be more beneficial as the difficulty of the listening task increased. The present data suggest that bimodal benefit may depend on the type of masker and/or the difficulty of the listening task.

Effects of age and duration of deafness on Mandarin speech understanding in competing speech by normal-hearing and cochlear implant children.

Due to poor perception of fundamental frequency (F0) cues that are important for lexical tone perception and talker segregation, pediatric Chinese cochlear implant (CI) users may be especially susceptible to informational masking. Here, speech recognition thresholds (SRTs) were measured in steady noise or competing speech in Mandarin-speaking CI and normal-hearing (NH) children. CI children were more susceptible to informational masking and were unable to use F0 cues to segregate talkers. SRTs were significantly correlated with chronological age in NH children and with duration of deafness in CI children, suggesting that auditory deprivation may limit developmental processes important for talker segregation.

Music Training Can Improve Music and Speech Perception in Pediatric Mandarin-Speaking Cochlear Implant Users.

Due to limited spectral resolution, cochlear implants (CIs) do not convey pitch information very well. Pitch cues are important for perception of music and tonal language; it is possible that music training may improve performance in both listening tasks. In this study, we investigated music training outcomes in terms of perception of music, lexical tones, and sentences in 22 young (4.8 to 9.3 years old), prelingually deaf Mandarin-speaking CI users. Music perception was measured using a melodic contour identification (MCI) task. Speech perception was measured for lexical tones and sentences presented in quiet. Subjects received 8 weeks of MCI training using pitch ranges not used for testing. Music and speech perception were measured at 2, 4, and 8 weeks after training was begun; follow-up measures were made 4 weeks after training was stopped. Mean baseline performance was 33.2%, 76.9%, and 45.8% correct for MCI, lexical tone recognition, and sentence recognition, respectively. After 8 weeks of MCI training, mean performance significantly improved by 22.9, 14.4, and 14.5 percentage points for MCI, lexical tone recognition, and sentence recognition, respectively ( p < .05 in all cases). Four weeks after training was stopped, there was no significant change in posttraining music and speech performance. The results suggest that music training can significantly improve pediatric Mandarin-speaking CI users' music and speech perception.

Bilaterally Combined Electric and Acoustic Hearing in Mandarin-Speaking Listeners: The Population With Poor Residual Hearing.

The hearing loss criterion for cochlear implant candidacy in mainland China is extremely stringent (bilateral severe to profound hearing loss), resulting in few patients with substantial residual hearing in the nonimplanted ear. The main objective of the current study was to examine the benefit of bimodal hearing in typical Mandarin-speaking implant users who have poorer residual hearing in the nonimplanted ear relative to those used in the English-speaking studies. Seventeen Mandarin-speaking bimodal users with pure-tone averages of ∼80 dB HL participated in the study. Sentence recognition in quiet and in noise as well as tone and word recognition in quiet were measured in monaural and bilateral conditions. There was no significant bimodal effect for word and sentence recognition in quiet. Small bimodal effects were observed for sentence recognition in noise (6%) and tone recognition (4%). The magnitude of both effects was correlated with unaided thresholds at frequencies near voice fundamental frequencies (F0s). A weak correlation between the bimodal effect for word recognition and unaided thresholds at frequencies higher than F0s was identified. These results were consistent with previous findings that showed more robust bimodal benefits for speech recognition tasks that require higher spectral resolution than speech recognition in quiet. The significant but small F0-related bimodal benefit was also consistent with the limited acoustic hearing in the nonimplanted ear of the current subject sample, who are representative of the bimodal users in mainland China. These results advocate for a more relaxed implant candidacy criterion to be used in mainland China.

The development and validation of the Closed-set Mandarin Sentence (CMS) test.

Matrix-styled sentence tests offer a closed-set paradigm that may be useful when evaluating speech intelligibility. Ideally, sentence test materials should reflect the distribution of phonemes within the target language. We developed and validated the Closed-set Mandarin Sentence (CMS) test to assess Mandarin speech intelligibility in noise. CMS test materials were selected to be familiar words and to represent the natural distribution of vowels, consonants, and lexical tones found in Mandarin Chinese. Ten key words in each of five categories (Name, Verb, Number, Color, and Fruit) were produced by a native Mandarin talker, resulting in a total of 50 words that could be combined to produce 100,000 unique sentences. Normative data were collected in 10 normal-hearing, adult Mandarin-speaking Chinese listeners using a closed-set test paradigm. Two test runs were conducted for each subject, and 20 sentences per run were randomly generated while ensuring that each word was presented only twice in each run. First, the level of the words in each category were adjusted to produce equal intelligibility in noise. Test-retest reliability for word-in-sentence recognition was excellent according to Cronbach's alpha (0.952). After the category level adjustments, speech reception thresholds (SRTs) for sentences in noise, defined as the signal-to-noise ratio (SNR) that produced 50% correct whole sentence recognition, were adaptively measured by adjusting the SNR according to the correctness of response. The mean SRT was -7.9 (SE=0.41) and -8.1 (SE=0.34) dB for runs 1 and 2, respectively. The mean standard deviation across runs was 0.93 dB, and paired t-tests showed no significant difference between runs 1 and 2 (p=0.74) despite random sentences being generated for each run and each subject. The results suggest that the CMS provides large stimulus set with which to repeatedly and reliably measure Mandarin-speaking listeners' speech understanding in noise using a closed-set paradigm.

Effect of spatial separation and noise type on sentence recognition by Mandarin-speaking cochlear implant users.

OBJECTIVES: To investigate the effects of spatial separation and noise type on sentence recognition by unilateral Mandarin-speaking cochlear implant (CI) users and normal-hearing (NH) listeners. METHOD: Twenty-two unilateral Mandarin-speaking CI users and six NH listeners participated in this study. Speech reception thresholds were measured for three noise types (steady state noise, speech babble, and music). Sentences from the Mandarin Speech Perception test were presented directly in front of the listener (0°). Noise was presented from one of the five speaker locations: -90°, -45°, 0°, +45°, and +90°. RESULTS: Overall, CI performance was significantly poorer than NH performance for all spatial separation and noise type conditions. NH listeners performed best with music and poorest with steady noise. CI users performed best with steady noise, and poorest with babble. Performance was significantly affected by noise location and noise type. There was no significant difference in head shadow effects among the different noise types for CI users. CONCLUSIONS: Performance was much poorer in CI than in NH listeners for all noise types and spatial separations. Noise type differently affected unilateral CI users and NH listeners. The limited spectral resolution in CI users did not appear to affect head shadow.

[Effects of cochlear implantation on ipsilateral tinnitus].

OBJECTIVE: Cochlear implantation is the current standard of care in patients with significant sensorineural hearing loss. The purpose of this study was to assess the effects of cochlear implantation on ipsilateral tinnitus. METHODS: With standard assessment table and standard testing program, 48 postlingual hearing-impaired adults aged 18 - 62 years (mean age at implantation: 35.0) were operated at 5 clinical centers from June 2009 to March 2010. There were 23 males (47.9%) and 25 females (52.1%). We evaluated the pre- and post-implantation degrees of tinnitus, performed free sound field audiometry and scored speech perception during different periods. Secondary analyses were conducted to examine the correlation between the effects of implantation on tinnitus and hearing or speech perception rehabilitation. RESULTS: Before implantation, there were 16 cases with ipsilateral tinnitus and 32 cases without tinnitus. After implantation, among 16 cases, the outcomes were recovery (n = 6), tinnitus suppression (n = 1) and no change in symptoms (n = 9). The total effective rate was 43.8%. Among another 32 cases without preoperative tinnitus, 2 cases developed tinnitus after implantation. The effects of cochlear implantation on tinnitus were negatively correlated with the course of tinnitus. There was no more correlation with other factors. CONCLUSION: Cochlear implants have significant therapeutic effects on tinnitus in 43.8% of implant users. Better efficacies are correlated with a shorter course of tinnitus. However, tinnitus suppression using electrical stimulation via cochlear implantation for deafness needs to be further evaluated.

[Efficacy of ossicular chain reconstruction using titanium implants in single-stage tympanoplasty].

OBJECTIVE: To explore the efficacy of total and partial ossicular chain reconstruction using titanium implants. METHODS: Total of 106 patients (107 ears) underwent ossiculoplasty using titanium from June 2008 to January 2011. Eighty-six ears had partial ossicular replacement prosthesis (PORP) and 21 ears had total ossicular replacement prosthesis (TORP). Patient data were collected retrospectively from the database of surgical cases. Patients were assessed during 6 to 30 months postoperatively to establish middle- and long-term hearing results. Average postoperative air-conduction gain and air-bone gap (ABG) were measured at four frequencies: 0.5, 1, 2, and 4 kHz. RESULTS: Postoperative air-bone gap of 20 dB or less than 20 dB was obtained in 83.7% of PORP cases versus 71.4% of TORP cases. All the cases obtained significant postoperative air-conduction gains. The change in air-bone gap (defined as the difference between the means of preoperative and postoperative ABG) was 12.5 dB for PORP patients and 12.9 dB for the TORP patients. There was no statistically significant difference between the TORP and PORP groups. Prosthesis exclusion was observed in one case (0.9%). CONCLUSION: Prostheses using titanium type could give good functional results and stability with low exclusion rate to patients presenting chronic otitis media.

[Tone recognition of REZ-1 multi-channel unilateral cochlear implants for profoundly postlingual deaf adults].

OBJECTIVE: To assess the tone recognition of cochlear-implant subjects by a REZ-1 device. METHODS: Speech recognition experiments were conducted to measure the tone recognition with standard assessment table and standard testing program. A total of 34 postlingual hearing-impaired adults who were native speakers of Mandarin undergoing operations from June to October, 2009 were tested and scored both preoperatively and postoperatively (1, 2, 3, 6, 12 months post-implantation) for speech recognition. RESULTS: All patient scores of speech recognition (initials, finals, monosyllabic words & tones) decreased gradually during the postoperative follow-up period. Preoperative speech recognition scores were all 0. And after a 12-month training, their average scores were increased significantly [(70 ± 8)% ± (82 ± 8)%]. Significant statistical differences existed between pre- and post-implantation in each test (P < 0.01). CONCLUSION: REZ-1 cochlear implantation may improve the tone recognition of adults with severe-to-profound postlingual hearing loss in a quiet environment.

[Effect of REZ-I cochlear implantation on residual hearing in adult patients].

OBJECTIVE: To evaluate the effect of cochlear implantation with REZ-I straight electrodes on residual hearing of postlingually deafened adults, and to explore the audiologically safety and injury characteristics of cochlear implantation. METHODS: Sixteen unilateral REZ-I (22 channels) cochlear implantation recipients from September 2009 to December 2009 were picked out. Their pre-and post-implantation audiometry data including pure-tone audiometry (PTA), auditory steady-state responses (ASSR), auditory brainstem responses (ABR) and distortion product otoacoustic emissions (DPOAE) were retrospectively analyzed, in order to compare the change between pre- and post-implantation residual hearing. RESULTS: Among the 12 recipients who had some measurable residual hearing before implantation, 5 (41.6%) patients had conserved some measurable hearing but the other 7 (58.4%) recipients had lost all measurable hearing after implantation on the implanted side. The implanted ears had an average PTA threshold drop of 9.5 dB HL and a statistically significant difference between pre- and post-implantation (P < 0.05) PTA thresholds in the frequencies of 250 Hz, 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz. Compared to non-implanted ears, the drop in 500 Hz and 1kHz had a statistically significant difference between pre- and post-implantation PTA thresholds (P < 0.05). The ASSR residual hearing threshold elevation were statistically significant (P < 0.05) between pre- and post-implantation ASSR at 250 Hz and 500 Hz on the implanted side, while the The ASSR residual hearing threshold elevation were statistically significant (P < 0.05) at 500 Hz when compared to non-implanted side. The difference of residual hearing between pre- and post-implantation was not statistically significant for both DPOAE and ABR. CONCLUSION: There will be a certain degree of damage to residual hearing of the implanted side following REZ-I cochlear implantation.