The P300 auditory event-related potential as a method to assess the benefit of contralateral hearing aid use in bimodal listeners: a proof-of-concept.

Objective: Bimodal listeners vary in the amount of benefit they receive from wearing the contralateral hearing aid. This may partially depend on the listener's auditory processing capacities. The current study explores whether the P300 event-related potential can provide insight into the mechanisms underlying the benefits of wearing a contralateral hearing aid.Design: P300s were recorded using an oddball paradigm with 500 and 250 Hz tone-bursts as standard and deviant stimuli, respectively. Subjects counted the number of deviants - a measure of performance. N2b latencies, P300 latencies, N2b-P300 amplitudes, and performance were assessed during CI-only and bimodal listening.Study sample: Five bimodal listeners.Results: P300s were present in four subjects. Amplitudes were larger during bimodal listening (bimodal: 22.3 ± 4.83 µV, CI-only: 13.1 ± 3.86 µV). Both N2b and P300 latencies were shorter during bimodal (N2b: 265 ± 20.0 ms, P300: 551 ± 129.4 ms) than CI-only listening (N2b: 326 ± 42.2 ms, P300: 402 ± 38.4 ms). While performance often reached ceiling level, the difference between the standard and deviant was generally more salient during bimodal listening.Conclusions: This study provides a proof-of-concept, suggesting that P300s may provide insight into benefits that are not always measurable with behavioural tasks.

Age-Related Changes in Binaural Interaction at Brainstem Level.

OBJECTIVES: Age-related hearing loss hampers the ability to understand speech in adverse listening conditions. This is attributed to a complex interaction of changes in the peripheral and central auditory system. One aspect that may deteriorate across the lifespan is binaural interaction. The present study investigates binaural interaction at the level of the auditory brainstem. It is hypothesized that brainstem binaural interaction deteriorates with advancing age. DESIGN: Forty-two subjects of various age participated in the study. Auditory brainstem responses (ABRs) were recorded using clicks and 500 Hz tone-bursts. ABRs were elicited by monaural right, monaural left, and binaural stimulation. Binaural interaction was investigated in two ways. First, grand averages of the binaural interaction component were computed for each age group. Second, wave V characteristics of the binaural ABR were compared with those of the summed left and right ABRs. RESULTS: Binaural interaction in the click ABR was demonstrated by shorter latencies and smaller amplitudes in the binaural compared with the summed monaural responses. For 500 Hz tone-burst ABR, no latency differences were found. However, amplitudes were significantly smaller in the binaural than summed monaural condition. An age-effect was found for 500 Hz tone-burst, but not for click ABR. CONCLUSIONS: Brainstem binaural interaction seems to decline with age. Interestingly, these changes seem to be stimulus-dependent.

Binaural interaction in the auditory brainstem response: a normative study.

OBJECTIVE: Binaural interaction can be investigated using auditory evoked potentials. A binaural interaction component can be derived from the auditory brainstem response (ABR-BIC) and is considered evidence for binaural interaction at the level of the brainstem. Although click ABR-BIC has been investigated thoroughly, data on 500 Hz tone-burst (TB) ABR-BICs are scarce. In this study, characteristics of click and 500 Hz TB ABR-BICs are described. Furthermore, reliability of both click and 500 Hz TB ABR-BIC are investigated. METHODS: Eighteen normal hearing young adults (eight women, ten men) were included. ABRs were recorded in response to clicks and 500 Hz TBs. ABR-BICs were derived by subtracting the binaural response from the sum of the monaural responses measured in opposite ears. RESULTS: Good inter-rater reliability is obtained for both click and 500 Hz TB ABR-BICs. The most reliable peak in click ABR-BIC occurs at a mean latency of 6.06 ms (SD 0.354 ms). Reliable 500 Hz TB ABR-BIC are obtained with a mean latency of 9.47 ms (SD 0.678 ms). Amplitudes are larger for 500 Hz TB ABR-BIC than for clicks. CONCLUSION: The most reliable peak in click ABR-BIC occurs at the downslope of wave V. Five hundred Hertz TB ABR-BIC is characterized by a broad positivity occurring at the level of wave V. SIGNIFICANCE: The ABR-BIC is a useful technique to investigate binaural interaction in certain populations. Examples are bilateral hearing aid users, bilateral cochlear implant users and bimodal listeners. The latter refers to the combination of unilateral cochlear implantation and contralateral residual hearing. The majority of these patients have residual hearing in the low frequencies. The current study suggests that 500 Hz TB ABR-BIC may be a suitable technique to assess binaural interaction in this specific population of cochlear implant users.

Multicentre investigation on electrically evoked compound action potential and stapedius reflex: how do these objective measures relate to implant programming parameters?

OBJECTIVES: The aims of this study were to collect data on electrically evoked compound action potential (eCAP) and electrically evoked stapedius reflex thresholds (eSRT) in HiResolution(TM) cochlear implant (CI) users, and to explore the relationships between these objective measures and behavioural measures of comfort levels (M-levels). METHODS: A prospective study on newly implanted subjects was designed. The eCAP was measured intra-operatively and at first fitting through neural response imaging (NRI), using the SoundWave(TM) fitting software. The eSRT was measured intra-operatively by visual monitoring of the stapes, using both single-electrode stimulation and speech bursts (four electrodes stimulated at the same time). Measures of M-levels were performed according to standard clinical practice and collected at first fitting, 3 and 6 months of CI use. RESULTS: One hundred seventeen subjects from 14 centres, all implanted unilaterally with a HiResolution CII Bionic Ear(®) or HiRes 90K(®), were included in the study. Speech burst stimulation elicited a significantly higher eSRT success rate than single-electrode stimulation, 84 vs. 64% respectively. The NRI success rate was 81% intra-operatively, significantly increasing to 96% after 6 months. Fitting guidelines were defined on the basis of a single NRI measurement. Correlations, analysis of variance, and multiple regression analysis were applied to generate a predictive model for the M-levels. DISCUSSION: Useful insights were produced into the behaviour of objective measures according to time, electrode location, and fitting parameters. They may usefully assist in programming the CI when no reliable feedback is obtained through standard behavioural procedures.

Characteristics and determinants of music appreciation in adult CI users.

The main objective of this study was to assess the associations between self-reported listening habits and perception of music and speech perception outcomes in quiet and noise for both unilateral cochlear implant (CI) users and bimodal (CI in one ear, hearing aid in contra-lateral ear) users. Information concerning music appreciation was gathered by means of a newly developed questionnaire. Moreover, audiological data (pure-tone audiometry, speech tests in noise and quiet) were gathered and the relationship between speech perception and music appreciation is studied. Bimodal users enjoy listening to music more in comparison with unilateral CI users. Also, music training within rehabilitation is still uncommon, while CI recipients believe that music training might be helpful to maximize their potential with current CI technology. Music training should not be exclusively reserved for the good speech performers. Therefore, a music training program (MTP) that consists of different difficulty levels should be developed. Hopefully, early implementation of MTP in rehabilitation programs can enable adult CI users to enjoy and appreciate music and to maximize their potential with commercially available technology. Furthermore, because bimodal users consider the bimodal stimulation to be the most enjoyable way to listen to music, CI users with residual hearing in the contra-lateral ear should be encouraged to continue wearing their hearing aid in that ear.

Impact of newborn hearing screening: comparing outcomes in pediatric cochlear implant users.

OBJECTIVES/HYPOTHESIS: To evaluate the impact of a newborn hearing screening program on the management and outcome of deaf children and to identify underlying factors that may be responsible for the differences between high and low performing implanted children. STUDY DESIGN: Retrospective cohort study of 391 implanted children in Flanders (Belgium). METHODS: First, implanted children were sorted into two groups on account of screening age (early screened, n = 195 vs. late screened, n = 196). Both groups were compared with respect to several variables. Second, outcome of cochlear implantation was measured in terms of the child's speech perception and production skills (n = 355). A subgroup of high performing cochlear implant (CI) users was compared with low performing CI users with regard to several variables. RESULTS: Early screened children differ significantly from late screened children with respect to age of hearing loss detection and age at cochlear implantation. Furthermore, early screening and implantation is associated with better auditory receptive skills and speech intelligibility. Additional impairments negatively influence both receptive and productive skills. In addition, children who communicate orally and wear bilateral cochlear implants perform better on speech production, whereas a better speech perception was found in children who became progressively deaf as opposed to congenitally deaf children. CONCLUSIONS: The results of this extensive study of profoundly deaf children with CIs in Flanders indicate that a newborn hearing screening program results in earlier intervention in deaf children, which beneficially influences the auditory receptive skills and speech intelligibility.

The vestibular evoked myogenic potential: a test-retest reliability study.

OBJECTIVE: The purpose of this study was to evaluate the reliability of the vestibular evoked myogenic potential (VEMP) response in a clinical setting when only a feedback mechanism is available for monitoring background EMG. METHODS: Sixty-one healthy subjects participated in the investigation of the within-session reliability, whereas fourteen of them were retested after one week for examination of the between-session reliability. VEMPs were recorded using 500 Hz tone bursts with the subjects in a sitting position and their heads turned away from the test ear to the contralateral shoulder, thereby pushing their chin against the inflatable cuff of a blood pressure manometer, serving as feedback method. RESULTS: The feedback method revealed latency and amplitude values comparable to other data in the literature where different test conditions were applied. Excellent reliability with ICC values ranging from 0.78 to 0.96 and CV(ME) values ranging from 4% to 36%, was achieved for P1 and N1 latency, threshold and interpeak amplitude. Good reliability with ICC values of 0.65 and 0.68 and CV(ME) values of 170% and 189%, was obtained for the asymmetry ratio. CONCLUSIONS: A unilateral muscle contraction controlled by a feedback mechanism resulted in reliable response parameters, comparable right to left and corresponding to literature data obtained in different test conditions. SIGNIFICANCE: The use of a blood pressure manometer as feedback mechanism combined with a meticulously controlled positioning of the head and contraction of the SCM muscle provides a reliable alternative in clinical settings, when the background muscle contraction cannot be measured or software related correction algorithms are not accessible.

Auditory steady-state responses in normal hearing adults: a test-retest reliability study.

The test-retest reliability of the auditory steady-state response (ASSR) has received limited attention. Therefore, the aim was to assess the test-retest reliability of an 80-Hz multiple-ASSR system in normal-hearing subjects by a comprehensive set of statistical methods. Twenty-nine participants (15 females) aged between 18 and 30 years contributed to two sessions (test-retest), and the ASSR thresholds were determined with a descending search protocol using a 10-dB precision. The test-retest reliability was assessed by a three-layered approach which consisted of Pearson product-moment correlation, analysis of variance (ANOVA), and standard error of measurement (SEM). The correlations for ASSR thresholds ranged from poor (0.34) for 500 Hz CF to moderate (0.55) for 1000, 2000, and 4000 Hz CF. A two-way ANOVA of the difference scores (ASSR threshold minus behavioral threshold) demonstrated no significant difference between test and retest. The SEM determined the normal tolerance for clinical error of repeated thresholds and the ASSR SEM values fell well within +/-10 dB HL. This investigation shows that the multiple ASSR-technique produces a clinically acceptable test-retest reliability for normal-hearing adults.

Normative data and test-retest reliability of the sinusoidal harmonic acceleration test, pseudorandom rotation test and velocity step test.

Rotational testing has been used in clinical practice to explore vestibular function. Frequently used stimulus algorithms include: sinusoidal harmonic acceleration test (SHAT), pseudorandom rotation test (PRRT), and velocity step test (VST). The aim of this study was to construct normative data as well as to evaluate the test-retest reliability of those rotational paradigms. One hundred and fifty subjects without vestibular history participated in the normative study. The SHAT was presented at 5 frequencies (0.01, 0.02, 0.05, 0.1, 0.2 Hz), whereas for the PRRT those frequencies were summed. The VST consisted of a rotation to the right and left and was administered twice. Thirty-two volunteers were retested to assess the test-retest reliability. Separate normative data were needed according to sex, stimulus type, and frequency for the SHAT and PRRT, and according to stimulus and direction for the VST. High reliability by means of the intraclass correlation coefficient (ICC) and the method error (ME) was obtained for the SHAT, PRRT, and VST gain, SHAT phase and asymmetry, and VST time constant parameters. The availability of data on the minimal detectable test-retest differences supports the evaluation of rotational responses on a retest session.

Auditory steady-state responses to MM and exponential envelope AM(2)/FM stimuli in normal-hearing adults.

The present study utilized a commercially available multiple auditory steady-state response (ASSR) system to test normal hearing adults (n=55). The primary objective was to evaluate the impact of the mixed modulation (MM) and the novel proposed exponential AM(2)/FM stimuli on the signal-to-noise ratio (SNR) and threshold estimation accuracy, through a within-subject comparison. The second aim was to establish a normative database for both stimulus types. The results demonstrated that the AM(2)/FM and MM stimulus had a similar effect on the SNR, whereas the ASSR threshold results revealed that the AM(2)/FM produced better thresholds than the MM stimulus for the 500, 1000, and 4000 Hz carrier frequency. The mean difference scores to tones of 500, 1000, 2000, and 4000 Hz were for the MM stimulus: 20+/-12, 14+/-9, 10+/-8, and 12+/-8 dB; and for the AM(2)/FM stimulus: 18+/-13, 12+/-8, 11+/-8, and 10+/-8 dB, respectively. The current research confirms that the AM(2)/FM stimulus can be used efficiently to test normal hearing adults.

Water irrigation versus air insufflation: a comparison of two caloric test protocols.

The aim of the present study was to construct and compare two caloric test protocols, one for water irrigation, and one for air insufflation. A set of reference data was constructed and tabulated as well as the intersubject variability. The effect of age, sex, ear, and temperature, as well as a possible priming effect and order effect were investigated. Forty-seven subjects (18-58 years) without otological or vestibular history participated. Four response parameters were investigated: slow component velocity (SCV), frequency, unilateral weakness (UW), and directional preponderance (DP). Statistically higher SCV values were obtained for water compared to air, with statistically higher standard deviations for SCV water values. No influences of age, sex, ear, or temperature could be demonstrated on any of the response parameters. The same applied for the presence of an order effect and a priming effect. Comparing the two protocols to one another led the present authors to favour water as the standard irrigation medium, and air only in situations where water is contra-indicated.

Distortion product otoacoustic emissions: an objective technique for the screening of hearing loss in children treated with platin derivatives.

In order to develop a sensitive audiometric protocol for identifying ototoxicity in children, a retrospective study of 16 children treated with cisplatin and/or carboplatin was performed. Audiometric testing was done by means of pure-tone threshold audiometry (PTA), high-frequency audiometry (HFA), and distortion product otoacoustic emissions (DPOAEs). Cisplatin caused a sensorineural high-frequency hearing loss in the study group compared to the controls (p < 0.01). Sixty-six percent of the cisplatin patients had a grade 2 or 3 ototoxicity. However, ototoxicity was not found in the patients treated with carboplatin. An excellent correlation was found between DPOAE levels and results obtained by audiometry (r = 0.82). Patients exposed to cisplatin are at significant risk for the development of drug-induced sensorineural hearing loss. Because of the several advantages of DPOAEs (noninvasive, objective, rapid, easy to use, sensitive) this method should be added in the audiological follow-up in infants and toddlers.

Comparison of the overall intelligibility, articulation, resonance, and voice characteristics between children using cochlear implants and those using bilateral hearing aids: a pilot study.

The purpose of this study was to determine and to compare the overall intelligibility, articulation, resonance, and voice characteristics in children using cochlear implants (CI) and children using conventional hearing aids (HA). Nine prelingually deaf children using CI and six children with a prelingual severe hearing loss using HA, were selected to participate. Objective (DSI, nasalance scores) as well as subjective assessment techniques (perceptual evaluations) were used. Both the CI and HA children demonstrated normal vocal quality and resonance but showed the presence of articulation disorders. In the CI children, intelligibility was significantly better compared to the HA children. Significantly more phonetic and phonological disorders were present in the HA children. The results of this study show a poorer intelligibility of the HA children in comparison with the CI children which is probably due to the occurrence of significantly more phonetic and phonological disorders. Future detailed analysis in a larger sample of CI and HA children may help further clarify the issue of speech and voice characteristics and may demonstrate an important prognostic value.

Cochlear implantation in a patient with superficial siderosis of the central nervous system.

OBJECTIVE: To perform an assessment of the viability of cochlear implantation in a patient with superficial siderosis of the brain. STUDY DESIGN: Case review. SETTING: Tertiary referral center. PATIENTS: Patient with superficial siderosis of the brain. INTERVENTION: Cochlear implantation. MAIN OUTCOME MEASURES: Electrically evoked auditory brainstem responses and fitting strategy for cochlear implant based on patient's subjective responses. RESULTS: After some time, C levels and T levels showed a pattern comparable with the evoked auditory brainstem responses. CONCLUSIONS: Bilateral profound hearing loss after superficial siderosis of the brain is no absolute contraindication for implantation. Furthermore, evoked auditory brainstem measurements can potentially guide the fitting process of the implant in difficult cases.