Improvement In Speech Discrimination Research Articles

Infants’ vowel discrimination in modulated and unmodulated noise.

Adults detect and discriminate masked sounds better in temporally modulated maskers than in unmodulated maskers. It is not known whether the same is true of infants. In this study, 7–9-month-olds learned to respond when a repeated vowel changed from /a/ to /i/ or from /i/ to /a/ in speech spectrum noise. Discrimination was assessed using an observer-based procedure. In one condition the noise was unmodulated. In the other, the noise was modulated with the envelope of single talker speech. The level of the noise was 60-dB SPL. For infants in group 1, the level of the vowel in both conditions was set so that d′=1 was achieved in the unmodulated noise; discrimination in modulated noise was the second condition tested. For infants in group 2, the level of the vowel was fixed at the average level used to test the infants in group 1; discrimination in modulated noise was tested first. In both groups, d′ in the modulated noise condition averaged only 0.5. Thus, infants were unable to take advantage of masker modulation to improve speech discrimination. Their speech discrimination was poorer in modulated than in unmodulated noise. [Work supported by NIH R01 DC00396 and P30 DC04661.]

Chirurgische Technik der Kochleaimplantation

The cochlear implant (CI) has become a standard option for treating prelingually deaf children. But postlingual late deafness in adults is becoming increasingly common. In addition, hybrid implantation with a CI and a hearing aid in the same ear has come into focus, which demands a soft insertion technique that spares the apical parts of the cochlea. Also, the chorda tympani should be saved, especially in bilateral implantations, which are gaining importance because improved speech discrimination in noisy conditions is seen as proven today. Control of the electrode position intraoperatively with intraoperative computed tomography can further increase the safety and reliability of the position. The position and length of the skin incision is a more aesthetic issue. Future developments will include fully implantable CIs and navigation-assisted, minimally invasive drilling of a hole from the surface of the skull into the cochlea. Bioactive, neurotrophic-drug-releasing electrode designs for improved and sustainable connectivity to the neurons may become applicable.

Benefits from a mobile telephone adapter in Combi40+ cochlear implant users

Conclusions. Telephone adapters can help cochlear implanted patients to enhance their telephonic conversations. However, these devices should be further developed to be useful for daily life. Objectives. To test a mobile telephone adapter to improve speech discrimination by mobile telephone in Combi40+ users. To evaluate the influence of the mobile telephone in communication. Subjects and methods. Seventeen Combi40+ implantees were tested with bisyllabic words presented through mobile telephones with and without a telephone adapter in quiet and noisy environments. Speech audiometries in open field were obtained for every patient. Results. Mean speech discrimination without the adapter in a quiet environment was 51.2%. In a noisy environment, mean discrimination increased significantly with the adapter from 30.3% to 42.9%. No statistically significant difference was found between speech discrimination in the quiet environment without the adapter and speech discrimination in the noisy environment with the adapter. When comparing speech discrimination in open field without lip-reading with equivalent telephonic conditions a statistically significant difference was found in favour of the open field.

Perceptual Training of Phoneme Identification for Hearing Loss

Synaptic connections in the auditory system change throughout life in response to the changing acoustic environment. These changes help to compensate for sensorineural hearing loss (SNHL) and the consequent impairment of high-frequency hearing by enhancing the efficiency of synaptic transmission of low-frequency signals. They also help to compensate for the inevitable deterioration in the central auditory system that occurs with normal aging even without clinically significant hearing loss. However, in many cases the neuroplastic changes are insufficient to maintain optimal speech comprehension. Indeed, the enhanced transmission of low-frequency phonetic cues that occurs with longstanding SNHL may interfere with a patient's ability to use the high-frequency phonetic cues that are restored by hearing aids. Adaptive perceptual training using tasks that require high-frequency phonetic cue processing can drive neuroplastic change in auditory cortex to improve speech discrimination. The authors tested the benefits of at-home personal computer-based phoneme identification training in new hearing aid (HA) users and found that it produced significant benefit in phoneme identification by reducing phonetic confusions and enhancing the patient's abilities to identify previously difficult syllables. Perceptual training is a promising and cost-effective tool for enhancing speech perception in HA users who have difficulty in understanding everyday speech.

Unilateral Deafness After Acoustic Neuroma Surgery

To evaluate the subjective hearing handicap in patients with unilateral deafness after acoustic neuroma surgery and the effect of the Bone-anchored Hearing Aid (BAHA) on test band. Fifty-nine consecutive patients with unilateral deafness after translabyrintine removal of an acoustic neuroma, treated in Denmark in 2001 and 2002, were included. The patients were asked to complete a questionnaire, which addressed the subjective handicap of unilateral deafness; 90% responded. These patients were invited to test the BAHA on test band, and the subjective and objective effects were recorded. Eighty percent of the patients thought that they had a subjective hearing handicap of some significance. However, only 50% accepted the invitation to test the BAHA. The overall subjective effect was positive, and a significant improvement in speech discrimination in noise with the BAHA was demonstrated. After the test, however, only about 50%, that is, 25% of all patients wished implantation for BAHA treatment. This study shows that unilateral deafness after acoustic neuroma surgery is thought as a handicap in most of the patients and confirms that treatment with the BAHA has positive subjective effects and improves speech discrimination in noise. However, only 25% of the patients wished implantation for BAHA treatment. The implications of these findings are discussed. Data from centers that perform simultaneous acoustic neuroma surgery and implantation for BAHA are necessary for firm conclusions.

Cross-modal reorganization and speech perception in cochlear implant users

Recent work suggests that once the auditory cortex of deaf persons has been reorganized by cross-modal plasticity, it can no longer respond to signals from a cochlear implant (CI) installed subsequently. To further examine this issue, we compared the evoked potentials involved in the processing of visual stimuli between CI users and hearing controls. The stimuli were concentric circles replaced by a different overlapping shape, inducing a shape transformation, known to activate the ventral visual pathway in human adults. All CI users had their device implanted for >1 year, but obtained different levels of auditory performance following training to establish language comprehension. Seven of the 13 patients showed good capacities for speech recognition with the CI (good performers) while the six others demonstrated poor speech recognition abilities (poor performers). The evoked potentials of all patients showed larger amplitudes, with different distributions of scalp activations between the two groups. The poor performers exhibited broader, anteriorly distributed, high P2 amplitudes over the cortex whereas the good performers showed significantly higher P2 amplitudes over visual occipital areas. These results suggest the existence of a profound cross-modal reorganization in the poor performers and an intramodal reorganization in the good performers. We interpret these data on the basis of enhanced audiovisual coupling as the key to a long-term functional improvement in speech discrimination in CI users.

Revision Cochlear Implantation for Facial Nerve Stimulation in Otosclerosis

To find if patients experiencing postsurgical facial nerve stimulation caused by underlying disease process (ie, otosclerosis) can improve their hearing performance with their cochlear implant by reimplantation and by an optimal programming strategy. Retrospective analysis. Academic tertiary referral center. Two cochlear otosclerosis patients with resistant facial nerve stimulation (FNS). Both patients were initially implanted with Nucleus 22 devices (Cochlear Corporation, Englewood, Colo) and they developed FNS after a period of use. Owing to the decreasing number of active electrodes, concurrent decreases in speech understanding occurred. Various programming approaches were used to address the FNS. Both subjects ultimately received Nucleus 24 devices. One was reimplanted in the same ear, and the other was implanted in the opposite ear. Both have been followed up for 8 months following the reimplantation. Cochlear implant programming levels, cochlear implant performance, and facial nerve stimulation. The FNS was managed for more than 3 years through optimized programming. However, the FNS progressed until performance dropped below acceptable levels. Reimplantation was believed to be the only option for improvement. After reimplantation and programming, both subjects showed immediate improvement in speech discrimination. One user increased his consonant-nucleus-consonant word score from 12% preoperatively to 42%, and the other's performance increased from 0% to 86%. Our results suggest that having more programming options with newer devices is critical in otosclerotic or ossified users who experience FNS. Also, reimplantation may be a useful tool to improve performance.

Etanercept Treatment for Autoimmune Inner Ear Disease: Results of a Pilot Placebo-Controlled Study

Autoimmune Inner Ear Disease (AIED) is an idiopathic progressive, often bilateral, sensironeural hearing loss that occurs over weeks to months, generally resulting in significant auditory disability. Response to treatment with immunomodulators other than corticosteroids has been poor. Data from a guinea pig model of AIED and a recent open label trial of etanercept suggested potential treatment benefit. Based on these preliminary results, we conducted a pilot placebo controlled trial of etanercept in AIED patients. Twenty AIED patients were enrolled in a 12-week blinded placebo (PLA) controlled randomized clinical trial of etanercept (ETA) with 25 mg SC twice weekly. Patients received treatment for 8 weeks with a 4-week follow-up off-treatment. The primary study endpoint was an improvement in pure tone threshold (PTA) of 10 Db in two consecutive frequencies and/or improvement in speech discrimination of >12% at week 8. Patient demographics were similar for the ETA and PLA patients. Seventeen subjects (8 ETA, 9 PLA) completed the trial. The 3 dropouts were due to lack of efficacy. One ETA and 2 PLA subjects achieved the primary endpoint (p > 0.999). One ETA and 1 PLA pt demonstrated improved in hearing loss and vertigo severity by VAS and hearing disability. No safety issues were observed. The results of this pilot trial demonstrate that etanercept 25 mg twice weekly for 8 weeks was no better than placebo for treatment of AIED in this patient population.

Effect of peri-modiolar cochlear implant positioning on auditory nerve responses: A neural response telemetry study

Conclusions. There was no evidence that a reduction in current was needed for nerve stimulation as a result of modiolar placement of a cochlear implant. However, modiolus hugging did reduce the spread of excitation for the basal and apical electrodes. This improved stimulation selectivity may result in improved speech discrimination by implant users. Objective. To test the effect of modiolar placement of a cochlear implant on stimulation thresholds, and to confirm whether peri-modiolar electrode placement resulted in the hypothesized reduced spread of excitation. Material and methods. Auditory nerve responses were measured by means of neural response telemetry (NRT) in 14 subjects. All subjects received a Nucleus CI24R(CS) Contour implant. For each subject, the stimulation threshold and response growth rate were determined on all the odd-numbered electrodes, using a masker-and-probe paradigm. In addition, the spatial spread of excitation was measured on electrodes 1, 6, 11, 16 and 20, using a variable-masker paradigm. All NRT measurements were performed intra-operatively, both before and after peri-modular placement of the electrode by removal of surgical stylet. Results. Removal of the stylet had no significant effect on the threshold and growth rate of NRT responses. It caused a reduction in the spread of excitation for electrodes 1, 6 and 20, but not for electrodes 11 and 16.

Steroid Perfusion of the Inner Ear for Sudden Sensorineural Hearing Loss after Failure of Conventional Therapy: A Pilot Study

The aim of this study was to determine if high-dose delivery of methylprednisolone to the round window can improve hearing after the failure of conventional treatment for sudden sensorineural hearing loss (SSHL). In 6 patients with SSHL an Intraear® microcatheter was placed in the round window niche and methylprednisolone (62.5 mg/ml) was infused at a rate of 10 w l/h for 8-10 days. Audiometric assessments (including measurement of speech discrimination) were made at presentation, either every day or every other day during treatment and 5 days after the completion of perfusion. Perfusion of methylprednisolone was beneficial for all 6 patients, with a 16.25-25 dB improvement in hearing threshold. A dramatic improvement in speech discrimination was also noted in all patients. In conclusion, methylprednisolone perfused at the level of the round window membrane resulted in significant recovery of hearing function after the failure of standard treatment of SSHL.

Use of auditory field measurement in patients with otosclerosis

Middle ear surgery sometimes leads to unpleasant auditory impressions such as distortion or hyperacusis that cannot be detected by conventional audiometric testing. Sixty-one patients with conductive hearing loss caused by otosclerosis underwent audiological evaluation, which included a questionnaire followed by testing of the audiometric threshold, speech audiometry, and assessment and quantification of loudness perception with a commercial system (WESTRA). This investigation includes the postoperative measurement of hearing improvement and the patients' subjective impressions regarding hearing increase, distortion of speech, and hyperacusis. Hearing improved in 88% of the patients. A quantification of this hearing increase was possible with pure tone audiometry and the Freiburg speech discrimination test. Reduced hearing threshold and lack of improvement in speech discrimination was confirmed by conventional hearing measurements. However, the presence of hyperacusis and distortion of speech could be determined by conventional audiometry in only 50% of cases. It was interesting to note that the subjects who reported speech distortion and hyperacusis in the questionnaire were identified by their increased loudness perception using the categorical loudness scaling. Category loudness scaling appears to be a valuable additional clinical test to characterize postoperative phenomena as distortion of speech and hyperacusis in patients undergoing stapes surgery.

A multichannel computer-enabled microphone array for use with hearing-impaired children in classrooms.

Many investigations have shown that background noise is generally more deleterious to the hearing-impaired student than a normal listener. Classroom acoustics impart a nearly intolerable noise level, excessive reverberation, and talker variations in intensity for the impaired ear. A low signal-to-noise ratio (S/N) is detrimental to the hearing-impaired student’s understanding of the speech signals from speakers within the classroom, and therefore does not optimize discrimination. Improved S/N can be obtained through the use of a microprocessor based multichannel microphone system. Scanning 32 microphones, a computer-enable microphone system, provides an efficient way to minimize the amount of background noise received by the hearing-impaired students, and consequently improve speech discrimination skills. Technical considerations for attack and release times and adaptive processing of background noise will be presented. Data are shown, which indicate with hearing-impaired students, the expected gains in speech discrimination with this and conventional auditory training systems.

Improved information transfer of phoneme features with a multiple-electrode cochlear implant.

The spectral maxima sound processor (SMSP), recently developed at the University of Melbourne, has been shown to provide improved speech discrimination in quiet and in noise for subjects using the Mini System 22 cochlear implant when compared with commercially available speech processors, including the Mini Speech Processor (MSP) [C. M. McKay and H. J. McDermott, J. Acoust. Soc. Am. 89, 1959 (1991)]. The ability of five subjects to perceive phoneme features using the SMSP has been compared with their ability using the MSP. Information transfer analysis has been applied to the results of open-set CNC word tests and closed-set vowel and consonant recognition tests. Phoneme features studied were consonant manner and place of articulation and voicing, vowel duration, formant frequencies, and formant transitions. The results show an overall improvement in the perception of all phoneme features, with large improvements seen in perception of consonant place of articulation. This consonant feature has been perceived poorly relative to other consonant features with all previous speech processors used with this implant. Further development of the SMSP is being guided by the results of this analysis.

Hearing improvement after acoustic tumor removal

Hearing improvement after removal of an acoustic tumor is an uncommon occurrence. Hearing improvement was observed in 8.5% of acoustic tumor removals performed using the middle fossa approach in an attempt to preserve hearing. Improvement in speech discrimination occurred most frequently and was of greatest magnitude compared with changes in the speech reception threshold or pure-tone average. No preoperative factors were predictive of postoperative hearing improvement. Findings support the conclusion that candidates for hearing preservation surgery should be chosen on the merits of their existing preoperative hearing and not on the basis of anticipated improvement.

Perception of sentences, words, and speech features by profoundly hearing-impaired children using a multichannel electrotactile speech processor

Fourteen prelinguistically profoundly hearing-impaired children were fitted with the multichannel electrotactile speech processor (Tickle Talker) developed by Cochlear Pty. Ltd. and the University of Melbourne. Each child participated in an ongoing training and evaluation program, which included measures of speech perception and production. Results of speech perception testing demonstrate clear benefits for children fitted with the device. Thresholds for detection of pure tones were lower for the Tickle Talker than for hearing aids across the frequency range 250-4000 Hz, with the greatest tactual advantage in the high-frequency consonant range (above 2000 Hz). Individual and mean speech detection thresholds for the Ling 5-sound test confirmed that speech sounds were detected by the electrotactile device at levels consistent with normal conversational speech. Results for three speech feature tests showed significant improvement when the Tickle Talker was used in combination with hearing aids (TA) as compared with hearing aids along (A). Mean scores in the TA condition increased by 11% for vowel duration, 20% for vowel formant, and 25% for consonant manner as compared with hearing aids alone. Mean TA score on a closed-set word test (WIPI) was 48%, as compared with 32% for hearing aids alone. Similarly, mean WIPI score for the combination of Tickle Talker, lipreading, and hearing aids (TLA) increased by 6% as compared with combined lipreading and hearing aid (LA) scores. Mean scores on open-set sentences (BKB) showed a significant increase of 21% for the tactually aided condition (TLA) as compared with unaided (LA). These results indicate that, given sufficient training, children can utilize speech feature information provided through the Tickle Talker to improve discrimination of words and sentences. These results indicate that, given sufficient training, children can utilize speech feature information provided through the Tickle Talker to improve discrimination of words and sentences. These results are consistent with improvement in speech discrimination previously reported for normally hearing and hearing-impaired adults using the device. Anecdotal evidence also indicates some improvements in speech production for children fitted with the Tickle Talker.

The effects of hearing aids on speech discrimination in noise by normal-hearinglisteners

This investigation measured the degree to which hearing aids degrade speech discrimination in noise. Ten normal-hearing subjects were tested for speech reception thresholds (SRT) in noise. The tests were repeated under two aided conditions: one used binaural behind-the-ear (BTE) aids, the other an experimental binaural high-fidelity aid fitted with in-the-ear transducers. To assess the loss of any directional cues under aided conditions, a test environment producing directional cues in both horizontal and vertical planes was employed. Results indicated a 3 dB deterioration of speech-to-noise ratio for frontal speech with the BTE aids. Despite this, mean SRTs, when averaged over several listening directions, differed by less than 1 dB from unaided levels under both aided conditions. This suggests that improvements in hearing aid fidelity and directional performance beyond that available in current BTE aids will do little to improve speech discrimination in noise, although other benefits may accrue.

Speech perception studies using a multichannel electrotactile speech processor, residual hearing, and lipreading

Three studies are reported on the speech perception of normally hearing and hearing-impaired adults using combinations of visual, auditory, and tactile input. In study 1, mean scores for four normally hearing subjects showed that addition of tactile information, provided through the multichannel electrotactile speech processor, to either audition alone (300-Hz low-pass-filtered speech) or lipreading plus audition resulted in significant improvements in phoneme and word discrimination scores. Information transmission analyses demonstrated the effectiveness of the tactile aid in providing cues to duration, F1 and F2 features for vowels, and manner of articulation features for consonants, especially features requiring detection and discrimination of high-frequency information. In study 2, six different cutoff frequencies were used for a low-pass-filtered auditory signal. Mean scores for vowel and consonant identification were significantly higher with the addition of tactile input to audition alone at each cutoff frequency up to 1500 Hz. The mean speechtracking rate was also significantly increased by the additional tactile input up to 1500 Hz. Study 3 examined speech discrimination of three hearing-impaired adults. Additional information available through the tactile aid was shown to improve speech discrimination scores; however, the degree of increase was inversely related to the level of residual hearing. Results indicate that the electrotactile aid may be useful for patients with little residual hearing and for the severely to profoundly hearing impaired, who could benefit from the high-frequency information presented through the tactile modality, but unavailable through hearing aids.

Small fenestra stapedectomy: technique and advantages.

We discuss the rationale and advantages of the small fenestra technique (SFT) of stapedectomy. When results from conventional stapedectomy techniques are compared with those of SFT, the small fenestra technique shows improved hearing in the high frequencies of 2,000, 4,000, and 8,000 Hz, improved speech discrimination, reduced vestibular disturbance, and reduced iatrogenic trauma to the cochlea.

Experiences with ESR (endolymphatic sac revascularization) in cases of sensorineural hearing-loss.

Experience based on 14 cases of severe-to-total sensorineural deafness, treated with endolymphatic sac revascularization, operation, is presented. Changes seen in the endolymphatic sacs and lateral sinuses of these patients have been detailed. Irrespective of the degree and duration of deafness, significant hearing gain (with good improvement in speech discrimination) was obtained in nine out of 14 cases (64.28 per cent). There was no improvement at all in one out of 14 (7.14 per cent), and there was a relapse of the hearing-loss two months post-operatively in one case (7.14 per cent). Tinnitus disappeared in the operated ear in three out of five cases (60 per cent) and vertigo improved considerably in four out of six cases (66.66 per cent). The follow-up in this series has been up to two years.

Small fenestra stapedectomy technique: reducing risk and improving hearing.

During the past 25 years many variations have emerged in stapedectomy, most of which centered around either a change in the prosthesis itself or in the type of oval window seal. The small fenestra stapedectomy technique (SFT) represents a change in surgical procedure rather than in prosthetic design. This technique offers the opportunity to improve hearing results while reducing risks in stapedectomy surgery. Four areas of significant improvement are seen in patients in whom the SFT was used: (1) improved hearing in the high frequencies of 2000, 4000, and 8000 Hz, (2) improved speech discrimination scores, (3) a significant reduction in the number of reported vestibular complaints, and (4) a reduction in the number of serious postoperative sensorineural hearing losses.