Modified T2 Statistics for Improved Detection of Aided Cortical Auditory Evoked Potentials in Hearing-Impaired Infants.

The cortical auditory evoked potential (CAEP) is a change in neural activity in response to sound, and is of interest for audiological assessment of infants, especially those who use hearing aids. Within this population, CAEP waveforms are known to vary substantially across individuals, which makes detecting the CAEP through visual inspection a challenging task. It also means that some of the best automated CAEP detection methods used in adults are probably not suitable for this population. This study therefore evaluates and optimizes the performance of new and existing methods for aided (i.e., the stimuli are presented through subjects' hearing aid(s)) CAEP detection in infants with hearing loss. Methods include the conventional Hotellings T2 test, various modified q-sample statistics, and two novel variants of T2 statistics, which were designed to exploit the correlation structure underlying the data. Various additional methods from the literature were also evaluated, including the previously best-performing methods for adult CAEP detection. Data for the assessment consisted of aided CAEPs recorded from 59 infant hearing aid users with mild to profound bilateral hearing loss, and simulated signals. The highest test sensitivities were observed for the modified T2 statistics, followed by the modified q-sample statistics, and lastly by the conventional Hotelling's T2 test, which showed low detection rates for ensemble sizes <80 epochs. The high test sensitivities at small ensemble sizes observed for the modified T2 and q-sample statistics are especially relevant for infant testing, as the time available for data collection tends to be limited in this population.

Extended high-frequency bone conduction audiometry Calibration of bone conductor transducers in the conventional and extended high-frequency range.

OBJECTIVE: To monitor ototoxicity, air conduction (AC) extended high frequency (EHF) thresholds can be measured up to 16 kHz. However, conductive hearing loss might influence these results. This is unfortunate because the EHF thresholds are important to follow the impact of ototoxic medication during therapy. Therefore a suitable bone conduction (BC) transducer and norm values for EHF BC measurements are needed. DESIGN: In this study three different BC transducers were used: the B71 (Radioear), the KH70 (Präcitronic), and the KLH96 (Westra). Hearing thresholds were measured from 0.125 to 16 kHz using AC transducers (Telephonics TDH39, Sennheiser HDA200), and BC thresholds from 0.25 to 8 kHz with the B71, and from 0.25 to 16 kHz with the KLH96 and KH70. STUDY SAMPLE: 60 ears of 30 normal hearing subjects were measured. RESULTS: The KLH96 showed the highest output for the high frequencies, and distortion measurements were similar to the KH70. The results show that EHF measurements are possible using the KLH96 and KH70 bone conductors. CONCLUSION: EHF BC measurements are reliable when using the KLH96 and KH70 bone conductors. The extended force sensitivity of the used artificial mastoid should be determined for a proper EHF BC calibration.

Distortion Product Otoacoustic Emission (DPOAE) Growth in Aging Ears with Clinically Normal Behavioral Thresholds.

Age-related hearing loss (ARHL) is a devastating public health issue. To successfully address ARHL using existing and future treatments, it is imperative to detect the earliest signs of age-related auditory decline and understand the mechanisms driving it. Here, we explore early signs of age-related auditory decline by characterizing cochlear function in 199 ears aged 10-65 years, all of which had clinically defined normal hearing (i.e., behavioral thresholds ≤ 25 dB HL from .25 to 8 kHz bilaterally) and no history of noise exposure. We characterized cochlear function by measuring behavioral thresholds in two paradigms (traditional audiometric thresholds from .25 to 8 kHz and Békésy tracking thresholds from .125 to 20 kHz) and distortion product otoacoustic emission (DPOAE) growth functions at f2 = 2, 4, and 8 kHz. Behavioral thresholds through a standard clinical frequency range (up to 8 kHz) showed statistically, but not clinically, significant declines across increasing decades of life. In contrast, DPOAE growth measured in the same frequency range showed clear declines as early 30 years of age, particularly across moderate stimulus levels (L2 = 25-45 dB SPL). These substantial declines in DPOAE growth were not fully explained by differences in behavioral thresholds measured in the same frequency region. Additionally, high-frequency Békésy tracking thresholds above ~11.2 kHz showed frank declines with increasing age. Collectively, these results suggest that early age-related cochlear decline (1) begins as early as the third or fourth decade of life, (2) is greatest in the cochlear base but apparent through the length of the cochlear partition, (3) cannot be detected fully by traditional clinical measures, and (4) is likely due to a complex mix of etiologies.

Neurophysiological correlates of residual inhibition in tinnitus: Hints for trait-like EEG power spectra.

OBJECTIVE: To investigate oscillatory brain activity changes following acoustic stimulation in tinnitus and whether these changes are associated with behavioral measures of tinnitus loudness. Moreover, differences in ongoing brain activity between individuals with and without residual inhibition (RI) are examined (responders vs. non-responders). METHODS: Three different types of noise stimuli were administered for acoustic stimulation in 45 tinnitus patients. Subjects resting state brain activity was recorded before and after stimulation via EEG alongside with subjective measurements of tinnitus loudness. RESULTS: Delta, theta and gamma band power increased, whereas alpha and beta power decreased from pre to post stimulation. Acoustic stimulation responders exhibited reduced gamma and a trend for enhanced alpha activity with the latter localized in the right inferior temporal gyrus. Post stimulation, individuals experiencing RI showed higher theta, alpha and beta power with a peak power difference in the alpha band localized in the right superior temporal gyrus. Neither correlations with behavioral tinnitus measures nor stimulus-specific changes in EEG activity were present. CONCLUSIONS: Our observations might be indicative of trait-specific forms of oscillatory signatures in different subsets of the tinnitus population related to acoustic tinnitus suppression. SIGNIFICANCE: Results and insights are not only useful to understand basic neural mechanisms behind RI but are also valuable for general neural models of tinnitus.

Effect of hyperbaric oxygen therapy and corticosteroid therapy in military personnel with acute acoustic trauma.

INTRODUCTION: Acute acoustic trauma (AAT) is a sensorineural hearing impairment due to exposure to an intense impulse noise which causes cochlear hypoxia. Hyperbaric oxygen therapy (HBO) could provide an adequate oxygen supply. The aim was to investigate the effectiveness of early treatment with combined HBO and corticosteroid therapy in patients with AAT compared with corticosteroid monotherapy. METHODS: A retrospective study was performed on military personnel diagnosed with AAT between November 2012 and December 2017. Inclusion criteria for HBO therapy were hearing loss of 30 dB or greater on at least one, 25 dB or more on at least two, or 20 dB or more on three or more frequencies as compared with the contralateral ear. RESULTS: Absolute hearing improvements showed significant differences (independent t-test) between patients receiving HBO and the control group at 500 Hz (p=0.014), 3000 Hz (p=0.023), 4000 Hz (p=0.001) and 6000 Hz (p=0.01) and at the mean of all frequencies (p=0.002). Relative hearing improvements were significantly different (independent t-test) at 4000 Hz (p=0.046) and 6000 Hz (p=0.013) and at all frequencies combined (p=0.005). Furthermore, the percentage of patients with recovery to the functional level required by the Dutch Armed Forces (clinical outcome score) was higher in the HBO group. CONCLUSIONS: Early-stage combination therapy for patients with AAT was associated with better audiometric results at higher frequencies and better clinical outcome score.

High Altitude Performance of Loudspeakers and Potential Impact on Audiometric Findings.

BACKGROUND: The evaluation of how air rarefaction can affect a loudspeaker performance at altitude implies the need for characterization of earphones during hypobaric conditions. The aim of this study was phonometric analysis at different altitudes of the acoustic output of a widely used earphone model, along with its consequences on audiological investigations conducted under such environmental conditions.METHODS: The transfer function of a TDH-39P earphone was analyzed with an artificial ear under nine different altitude levels, from sea level up to 35,000 ft, inside a hypobaric chamber. A specific phonometric system not sensitive to environmental pressure changes was used. Other potentially confounding factors, such as environmental temperature and humidity, were continuously monitored.RESULTS: No relevant temperature or humidity changes were detected. The sound pressure level generated by the earphone under hypobaric conditions was found considerably affected by air density changes. These data produced a correction table aiming at recalibrating the earphone's output at each audiometric octave test frequency within the 250-8000 Hz range. Quite different characteristics of response were observed at different audiometric frequencies. Such findings were particularly evident for altitudes exceeding 12,000 ft.DISCUSSION: The development of a frequency-selective and altitude-related correction factor for acoustic stimuli is an essential aspect when hearing threshold measurements in hypobaric environments are performed.Lucertini M, Botti T, Sanjust F, Cerini L, Autore A, Lucertini L, Sisto R. High altitude performance of loudspeakers and potential impact on audiometric findings. Aerosp Med Hum Perform. 2019; 90(7):655-659.

A Comparison of Behavioral Methods for Indexing the Auditory Processing of Temporal Fine Structure Cues.

Purpose Growing evidence supports the inclusion of perceptual tests that quantify the processing of temporal fine structure (TFS) in clinical hearing assessment. Many tasks have been used to evaluate TFS in the laboratory that vary greatly in the stimuli used and whether the judgments require monaural or binaural comparisons of TFS. The purpose of this study was to compare laboratory measures of TFS for inclusion in a battery of suprathreshold auditory tests. A subset of available TFS tasks were selected on the basis of potential clinical utility and were evaluated using metrics that focus on characteristics important for clinical use. Method TFS measures were implemented in replication of studies that demonstrated clinical utility. Monaural, diotic, and dichotic measures were evaluated in 11 young listeners with normal hearing. Measures included frequency modulation (FM) tasks, harmonic frequency shift detection, interaural phase difference (TFS-low frequency), interaural time difference (ITD), monaural gap duration discrimination, and tone detection in noise with and without a difference in interaural phase (N0S0, N0Sπ). Data were compared with published results and evaluated with metrics of consistency and efficiency. Results Thresholds obtained were consistent with published data. There was no evidence of predictive relationships among the measures consistent with a homogenous group. The most stable tasks across repeated testing were TFS-low frequency, diotic and dichotic FM, and N0Sπ. Monaural and diotic FM had the lowest normalized variance and were the most efficient accounting for differences in total test duration, followed by ITD. Conclusions Despite a long stimulus duration, FM tasks dominated comparisons of consistency and efficiency. Small differences separated the dichotic tasks FM, ITD, and N0Sπ. Future comparisons following procedural optimization of the tasks will evaluate clinical efficiency in populations with impairment.

Unpleasantness of Amplified Environmental Sound Used in Tinnitus Sound Therapy: A Preliminary Study of Clinical Assessment.

OBJECTIVES: In this study, our aim was to use environmental sounds amplified in the frequency region corresponding to the tinnitus frequency of individual patients and apply them as sound therapy in tinnitus retraining therapy (TRT). In this pilot study, we 1) investigated the unpleasantness of processed environmental sounds using the amplification, attenuation, and removal in different frequency regions; 2) compared the unpleasantness of processed sounds for older and younger groups of participants; and 3) determined the amplification level appropriate for a clinical test. MATERIALS AND METHODS: We processed the sound of a river with three types of modification (amplified, attenuated, and notched) at a one-octave width of seven central frequencies, in the range 250-8000 Hz. Amplified and attenuated sounds were processed with five positive gains (+6, +12, +15.6, +18, and +20 dB) and two negative gains (-6 and -12 dB). Twenty-three older participants and 23 younger participants rated the unpleasantness of sounds using a visual analog scale. RESULTS: We found that, in the older group, there was no difference in unpleasantness among the three modifications. Older participants rated the level of unpleasantness as lower than younger participants for processed sounds in the high-frequency region. There were no marked differences among the amplification levels in the group of older participants. CONCLUSION: Based on the results, we decided that our clinical study would target older patients who had a tinnitus frequency over 4000 Hz and would compare the effect of an amplified sound with a 20 dB gain at the frequency corresponding to individual tinnitus with notched sound.

Binaural advantages in using a cochlear implant for adults with profound unilateral hearing loss.

BACKGROUND: Recent studies of cochlear implants (CIs) in profound unilateral hearing loss (UHL) patients have demonstrated a restoration of some binaural hearing. AIMS/OBJECTIVES: The objective was to evaluate three possible advantages of binaural hearing in CIs adult users with UHL including single-side deafness (SSD) and asymmetric hearing loss (AHL) subgroups. MATERIAL AND METHODS: A prospective study was conducted that included 70 sequentially implanted patients. Subgroups of these subjects included 64 with a postlingual onset of a profound hearing loss on the implanted side and 6 with a prelingual onset of that loss. Three binaural effects - redundancy, head shadow, and squelch - were evaluated. RESULTS: Significant differences between the 'CI on' and 'CI off' conditions were found for all three binaural effects for the study group as a whole and for the postlingual subgroup. However, results for the subjects in the prelingual subgroup did not demonstrate any of the binaural advantages. CONCLUSION AND SIGNIFICANCE: Patients with a postlingual onset of a profound hearing loss in one ear and normal hearing or only a moderate loss in the other ear are able to make the effective use of a CI in the profound-loss ear in conjunction with acoustic stimulation of the other ear.

High frequency transient-evoked otoacoustic emission measurements using chirp and click stimuli.

Transient-evoked otoacoustic emissions (TEOAEs) at high frequencies are a non-invasive physiological test of basilar membrane mechanics at the basal end, and have clinical potential to detect risk of hearing loss related to outer-hair-cell dysfunction. Using stimuli with constant incident pressure across frequency, TEOAEs were measured in experiment 1 at low frequencies (0.7-8 kHz) and high frequencies (7.1-14.7 kHz) in adults with normal hearing up to 8 kHz and varying hearing levels from 9 to 16 kHz. In combination with click stimuli, chirp stimuli were used with slow, medium and fast sweep rates for which the local frequency increased or decreased with time. Chirp TEOAEs were transformed into equivalent click TEOAEs by inverse filtering out chirp stimulus phase, and analyzed similarly to click TEOAEs. To improve detection above 8 kHz, TEOAEs were measured in experiment 2 with higher-level stimuli and longer averaging times. These changes increased the TEOAE signal-to-noise ratio (SNR) by 10 dB. Slower sweep rates were investigated but the elicited TEOAEs were detected in fewer ears compared to faster rates. Data were acquired in adults and children (age 11-17 y), including children with cystic fibrosis (CF) treated with ototoxic antibiotics. Test-retest measurements revealed satisfactory repeatability of high-frequency TEOAE SNR (median of 1.3 dB) and coherence synchrony measure, despite small test-retest differences related to changes in forward and reverse transmission in the ear canal. The results suggest the potential use of such tests to screen for sensorineural hearing loss, including ototoxic loss. Experiment 2 was a feasibility study to explore TEOAE test parameters that might be used in a full-scale study to screen CF patients for risk of ototoxic hearing loss.

Objective Binaural Loudness Balancing Based on 40-Hz Auditory Steady-State Responses. Part II: Asymmetric and Bimodal Hearing.

In Part I, we investigated 40-Hz auditory steady-state response (ASSR) amplitudes for the use of objective loudness balancing across the ears for normal-hearing participants and found median across-ear ratios in ASSR amplitudes close to 1. In this part, we further investigated whether the ASSR can be used to estimate binaural loudness balance for listeners with asymmetric hearing, for whom binaural loudness balancing is of particular interest. We tested participants with asymmetric hearing and participants with bimodal hearing, who hear with electrical stimulation through a cochlear implant (CI) in one ear and with acoustical stimulation in the other ear. Behavioral loudness balancing was performed at different percentages of the dynamic range. Acoustical carrier frequencies were 500, 1000, or 2000 Hz, and CI channels were stimulated in apical or middle regions in the cochlea. For both groups, the ASSR amplitudes at balanced loudness levels were similar for the two ears, with median ratios between left and right ear stimulation close to 1. However, individual variability was observed. For participants with asymmetric hearing loss, the difference between the behavioral balanced levels and the ASSR-predicted balanced levels was smaller than 10 dB in 50% and 56% of cases, for 500 Hz and 2000 Hz, respectively. For bimodal listeners, these percentages were 89% and 60%. Apical CI channels yielded significantly better results (median difference near 0 dB) than middle CI channels, which had a median difference of -7.25 dB.

Exploring Optimal Stimulus Frequency Ratio for Measurement of the Quadratic f2-f1 Distortion Product Otoacoustic Emission in Humans.

Purpose: Distortion product otoacoustic emissions (DPOAEs) are a by-product of active cochlear processes that lead to the compressive nonlinearity of healthy ears. The most commonly studied emission is at the frequency 2f1-f2, but there has been recent interest in using the quadratic distortion product at the frequency f2-f1 to detect cochleopathies including endolymphatic hydrops. Before the DPOAE at f2-f1 can be applied clinically in any capacity, optimal stimulus parameters for its elicitation must be established. Method: We investigated stimulus parameters for the DPOAEs at f2-f1 and 2f1-f2 in 23 adults with normal hearing. Logarithmically swept tones between approximately 0.6 and 20 kHz (L1 = L2 = 70 dB SPL) served as the higher frequency stimulus (f2). DPOAEs were measured for 6 f2/f1 ratios: 1.14, 1.18, 1.22, 1.30, 1.32, and 1.36. Results: Both DPOAEs were consistently measurable. In line with previous investigations, the highest levels of the DPOAE at 2f1-f2 were generated between f2/f1 ratios of 1.14-1.22, with a peak in the level ratio function at 1.22. In contrast, f2-f1 was less influenced by ratio, although the narrowest ratio (1.14) produced slightly higher levels across frequency. Conclusion: The DPOAE at f2-f1 is measurable in individuals with normal hearing up to f2 of 20 kHz at narrow f2/f1 ratios. Measurements at additional stimulus levels and in subjects with hearing impairment will be needed before clinical implementation.

Development of a method for determining binaural sensitivity to temporal fine structure.

OBJECTIVE: To develop and evaluate a test of the ability to process binaural temporal-fine-structure (TFS) information. The test was intended to provide a graded measure of TFS sensitivity for all listeners. DESIGN: Sensitivity to TFS was assessed at a sensation level of 30 dB using the established TFS-LF test at centre frequencies of 250, 500 and 750 Hz, and using the new TFS-AF test, in which the interaural phase difference (IPD) was fixed and the frequency was adaptively varied. IPDs varied from 30 to 180°. STUDY SAMPLE: Nine young (19-25 years) and 23 older (47-84 years) listeners with normal hearing over the tested frequency range. RESULTS: For the young listeners, thresholds on the TFS-AF test did not improve significantly with repeated testing. The rank-ordering of performance across listeners was independent of the size of the IPD, and moderate-to-strong correlations were observed between scores for the TFS-LF and TFS-AF tests. Older listeners who were unable to complete the TFS-LF test were all able to complete the TFS-AF test. CONCLUSIONS: No practice effects and strong correlations with an established test of binaural TFS sensitivity make the TFS-AF test a good candidate for the assessment of supra-threshold binaural processing.

Hearing loss and speech perception in noise difficulties in Fanconi anemia.

OBJECTIVES/HYPOTHESIS: Fanconi anemia is a hereditary chromosomal instability disorder. Hearing loss and ear abnormalities are among the many manifestations reported in this disorder. In addition, Fanconi anemia patients often complain about hearing difficulties in situations with background noise (speech perception in noise difficulties). Our study aimed to describe the prevalence of hearing loss and speech perception in noise difficulties in Dutch Fanconi anemia patients. STUDY DESIGN: Retrospective chart review. METHODS: A retrospective chart review was conducted at a Dutch tertiary care center. All patients with Fanconi anemia at clinical follow-up in our hospital were included. Medical files were reviewed to collect data on hearing loss and speech perception in noise difficulties. RESULTS: In total, 49 Fanconi anemia patients were included. Audiograms were available in 29 patients and showed hearing loss in 16 patients (55%). Conductive hearing loss was present in 24.1%, sensorineural in 20.7%, and mixed in 10.3%. A speech in noise test was performed in 17 patients; speech perception in noise was subnormal in nine patients (52.9%) and abnormal in two patients (11.7%). CONCLUSIONS: Hearing loss and speech perception in noise abnormalities are common in Fanconi anemia. Therefore, pure tone audiograms and speech in noise tests should be performed, preferably already at a young age, because hearing aids or assistive listening devices could be very valuable in developing language and communication skills. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:2358-2361, 2017.

Pitch Matching between Electrical Stimulation of a Cochlear Implant and Acoustic Stimuli Presented to a Contralateral Ear with Residual Hearing.

BACKGROUND: Cochlear implants (CIs) successfully restore hearing in postlingually deaf adults, but in doing so impose a frequency-position function in the cochlea that may differ from the physiological one. PURPOSE: The CI-imposed frequency-position function is determined by the frequency allocation table programmed into the listener's speech processor and by the location of the electrode array along the cochlea. To what extent can postlingually deaf CI users successfully adapt to the difference between physiological and CI-imposed frequency-position functions? RESEARCH DESIGN: We attempt to answer the question by combining behavioral measures of electroacoustic pitch matching (PM) and measures of electrode location within the cochlea. STUDY SAMPLE: The participants in this study were 16 adult CI users with residual hearing who could match the pitch of acoustic pure tones presented to their unimplanted ears to the pitch resulting from stimulation of different CI electrodes. DATA COLLECTION AND ANALYSIS: We obtained data for four to eight apical electrodes from 16 participants with CIs (most of whom were long-term users), and estimated electrode insertion angle for 12 of these participants. PM functions in this group were compared with the two frequency-position functions discussed above. RESULTS: Taken together, the findings were consistent with the possibility that adaptation to the frequency-position function imposed by CIs does happen, but it is not always complete. CONCLUSIONS: Some electrodes continue to be perceived as higher pitched than the acoustic frequencies with which they are associated despite years of listening experience after cochlear implantation.

Potential Benefits of an Integrated Electric-Acoustic Sound Processor with Children: A Preliminary Report.

BACKGROUND: A number of published studies have demonstrated the benefits of electric-acoustic stimulation (EAS) over conventional electric stimulation for adults with functional low-frequency acoustic hearing and severe-to-profound high-frequency hearing loss. These benefits potentially include better speech recognition in quiet and in noise, better localization, improvements in sound quality, better music appreciation and aptitude, and better pitch recognition. There is, however, a paucity of published reports describing the potential benefits and limitations of EAS for children with functional low-frequency acoustic hearing and severe-to-profound high-frequency hearing loss. PURPOSE: The objective of this study was to explore the potential benefits of EAS for children. RESEARCH DESIGN: A repeated measures design was used to evaluate performance differences obtained with EAS stimulation versus acoustic- and electric-only stimulation. STUDY SAMPLE: Seven users of Cochlear Nucleus Hybrid, Nucleus 24 Freedom, CI512, and CI422 implants were included in the study. DATA COLLECTION AND ANALYSIS: Sentence recognition (assayed using the pediatric version of the AzBio sentence recognition test) was evaluated in quiet and at three fixed signal-to-noise ratios (SNR) (0, +5, and +10 dB). Functional hearing performance was also evaluated with the use of questionnaires, including the comparative version of the Speech, Spatial, and Qualities, the Listening Inventory for Education Revised, and the Children's Home Inventory for Listening Difficulties. RESULTS: Speech recognition in noise was typically better with EAS compared to participants' performance with acoustic- and electric-only stimulation, particularly when evaluated at the less favorable SNR. Additionally, in real-world situations, children generally preferred to use EAS compared to electric-only stimulation. Also, the participants' classroom teachers observed better hearing performance in the classroom with the use of EAS. CONCLUSIONS: Use of EAS provided better speech recognition in quiet and in noise when compared to performance obtained with use of acoustic- and electric-only stimulation, and children responded favorably to the use of EAS implemented in an integrated sound processor for real-world use.

Inner Ear Excitation in Normal and Postmastoidectomy Participants by Fluid Stimulation in the Absence of Air- and Bone-Conduction Mechanisms.

BACKGROUND: Hearing can be induced not only by airborne sounds (air conduction [AC]) and by the induction of skull vibrations by a bone vibrator (osseous bone conduction [BC]), but also by inducing vibrations of the soft tissues of the head, neck, and thorax. This hearing mode is called soft tissue conduction (STC) or nonosseous BC. PURPOSE: This study was designed to gain insight into the mechanism of STC auditory stimulation. RESEARCH DESIGN: Fluid was applied to the external auditory canal in normal participants and to the mastoidectomy common cavity in post-radical mastoidectomy patients. A rod coupled to a clinical bone vibrator, immersed in the fluid, delivered auditory frequency vibratory stimuli to the fluid. The stimulating rod was in contact with the fluid only. Thresholds were assessed in response to the fluid stimulation. STUDY SAMPLE: Eight ears in eight normal participants and eight ears in seven post-radical mastoidectomy patients were studied. DATA COLLECTION AND ANALYSIS: Thresholds to AC, BC, and fluid stimulation were assessed. The postmastoidectomy patients were older than the normal participants, with underlying sensorineural hearing loss (SNHL). Therefore, the thresholds to the fluid stimulation in each participant were corrected by subtracting his BC threshold, which expresses any underlying SNHL. RESULTS: Hearing thresholds were obtained in each participant, in both groups in response to the fluid stimulation at 1.0 and 2.0 kHz. The fluid thresholds, corrected by subtracting the BC thresholds, did not differ between the groups at 1.0 kHz. However, at 2.0 kHz the corrected fluid thresholds in the mastoidectomy patients were 10 dB lower (better) than in the normal participants. CONCLUSIONS: Since the corrected fluid thresholds at 1.0 kHz did not differ between the groups, the response to fluid stimulation in the normal participants at least at 1.0 kHz was probably not due to vibrations of the tympanic membrane and of the ossicular chain induced by the fluid stimulation, since these structures were absent in the mastoidectomy patients. In addition, the fluid in the external canal (normal participants) and the absence of the tympanic membrane and the ossicular chain (mastoidectomy patients) induced a conductive hearing loss (threshold elevation to air-conducted sounds coming from the bone vibrator), so that AC mechanisms were probably not involved in the thresholds to the fluid stimulation. In addition, as a result of the acoustic impedance mismatch between the fluid and skull bone, the audio-frequency vibrations induced in the fluid at threshold would probably not lead to vibrations of the bony wall of the meatus, so that hearing by osseous BC is not likely. Therefore, it seems that the thresholds to the fluid stimulation, in the absence of AC and of osseous BC, represent an example of STC, which is an additional mode of auditory stimulation in which the cochlea is activated by fluid pressures transmitted along a series of soft tissues, reaching and exciting the inner ear directly. STC can explain the mechanism of several auditory phenomena.

Comparison of threshold estimation in infants with hearing loss or normal hearing using auditory steady-state response evoked by narrow band CE-chirps and auditory brainstem response evoked by tone pips.

OBJECTIVE: The objective of this study is to compare air-conduction thresholds obtained with ASSR evoked by narrow band (NB) CE-chirps and ABR evoked by tone pips (tpABR) in infants with various degrees of hearing loss. DESIGN: Thresholds were measured at 500, 1000, 2000 and 4000 Hz. Data on each participant were collected at the same day. STUDY SAMPLE: Sixty-seven infants aged 4 d to 22 months (median age = 96 days), resulting in 57, 52, 87 and 56 ears for 500, 1000, 2000 and 4000 Hz, respectively. RESULTS: Statistical analysis was performed for ears with hearing loss (HL) and showed a very strong correlation between tpABR and ASSR evoked by NB CE-chirps: 0.90 (n = 28), 0.90 (n = 28), 0.96 (n = 42) and 0.95 (n = 30) for 500, 1000, 2000 and 4000 Hz, respectively. At these frequencies, the mean difference between tpABR and ASSR was -3.6 dB (± 7.0), -5.2 dB (± 7.3), -3.9 dB (± 5.2) and -5.2 dB (± 4.7). Linear regression analysis indicated that the relationship was not influenced by the degree of hearing loss. CONCLUSION: We propose that dB nHL to dB eHL correction values for ASSR evoked by NB CE-chirps should be 5 dB lower than values used for tpABR.

La eficacia del tratamiento individual de los acúfenos subjetivos con terapia cognitiva-conductual / The efficacy of individual treatment of subjective tinnitus with cognitive behavioural therapy

Introducción: Los acúfenos subjetivos, a pesar del tiempo transcurrido desde que fueron descritos por primera vez, continúan sin tener un tratamiento con eficacia demostrada. El objetivo de este artículo es valorar la eficacia de la terapia cognitiva-conductual en el tratamiento de estos enfermos. Pacientes y métodos: Durante un periodo de tiempo de los años 2012-2013 se estudia a 310 enfermos que presentaban acúfenos subjetivos. De ellos, 267 fueron incluidos en un tratamiento basado en terapia cognitiva-conductual. El periodo de seguimiento fue de 18 meses y en 11 enfermos de 21 meses. Resultados: Considerando los enfermos que interrumpieron el tratamiento como fracasos, el porcentaje de curación fue de 95,7%. Conclusión: La terapia cognitiva-conductual debe estar siempre incluida en el tratamiento de los enfermos de acúfenos (AU)

Introduction: It has been a long time since subjective tinnitus cases were described for the first time but they still lack a treatment with proven effectiveness. The main goal of this study was to evaluate the effectiveness of cognitive behavioural therapy in these patients. Patients and method: Between 2012 and 2013, 310 patients that suffered from subjective tinnitus were studied. Of these, 267 were included in treatment based on cognitive behavioural therapy. The monitoring period lasted 18 months for most cases, while it lasted 21 months for 11 patients. Results: Considering patients that interrupted their treatment as failures, the percentage of recovery was 95.7%. Conclusion: Cognitive behavioural therapy should always be included in the treatment of people suffering from tinnitus (AU)