Hearing in Noise With Unilateral Versus Bilateral Bone Conduction Hearing Aids in Adults With Pseudo-conductive Hearing Loss.

OBJECTIVE: The role of bilateral bone conduction amplification in patients with bilateral conductive hearing loss is unclear because cranial attenuation is usually considered negligible, and both cochleae can be stimulated with similar efficacy by each device. The aim of the study was to determine if bilateral bone-conduction hearing aids can improve hearing in noise in a homogeneous group of normal-hearing subjects with bilateral pseudo-conductive hearing loss. STUDY DESIGN: Prospective, comparative. SETTING: Department of Communication Sciences and Disorders in University of Haifa, Israel. SUBJECTS: Department of Communication Sciences and Disorders in University of Haifa, Israel. INTERVENTIONS: Induction of bilateral pseudo-conductive hearing loss of more than 35 dB using earplugs and earmuffs. MAIN OUTCOME MEASURES: Hearing quality on blinded comparison of unilateral versus bilateral amplification with bone-conduction hearing aids under different locations of noise. RESULTS: Unilateral and bilateral amplification had similar efficacy when both signal and noise were presented from the front. However, bilateral amplification was significantly better when signals were presented from the front and noise was presented from both sides (SNR -10: 92% vs. 84%, p = 0.001; SNR -15: 84% vs. 78%, p = 0.005). Analysis of subject responses on blinded questionnaires revealed that 81% found hearing easier with bilateral amplification. Noise was reported to be more disturbing with unilateral amplification by 55% of the subjects and with bilateral amplification, by 9%. CONCLUSIONS: Bilateral amplification with bone conduction devices can improve understanding in noise in the binaural squelch setting. Subjective improvements with bilateral bone-conduction aids included better sound quality and reduced noise disturbance. These findings are consistent with the binaural mechanism of spectral release from masking.

Otoacoustic emissions in the prediction of sudden sensorineural hearing loss outcome.

OBJECTIVE: To evaluate the role of otoacoustic emissions (OAEs) in the prediction of idiopathic sudden sensorineural hearing loss (ISSNHL) outcome. STUDY DESIGN: Open-label prospective study. SETTING: Tertiary referral medical center. PATIENTS: Fifteen ISSNHL patients (age: 57.6 ± 16.2 years) were prospectively followed 7 days, 14 days, and 3 months post-presentation and the commencement of treatment. INTERVENTION: Pure-tone audiometry, TEOAEs (Transient Evoked OAEs), and DPOAEs (Distortion Product OAEs) testing. MAIN OUTCOME MEASURES: The pure-tone threshold averages of the three most affected frequencies, detectability, and the signal-to-noise ratios (SNRs) values of the TEOAEs and DPOAEs were calculated. The main outcome measures were pure-tone hearing improvement, sensitivity, and specificity of the OAEs measures towards ISSNHL outcome. RESULTS: Patients having detectable TEOAEs on the first follow-up evaluation had average hearing improvement of 62 ± 41% whereas those with no response improved only by 11 ± 15% (P < 0.001). For the DPOAEs hearing improvement, results were 71 ± 37% and 10 ± 14%, respectively (P < 0.001). The sensitivity of recordable TEOAEs on the seventh day of follow-up towards the prediction of significant hearing improvement reached 71% and the specificity 100%. For the DPOAEs, the corresponding values were 83% and 100%. Univariate analysis showed significant contribution for the variance in hearing improvement by both TEOAEs and DPOAEs and their interaction (P values of 0.043, 0.005, and 0.009, respectively). CONCLUSION: The results suggest potential role of TEOAEs and DPOAEs evaluation in the early stage of treatment in the prediction of ISSNHL outcome.

Air-bone gap component of inner-ear origin in audiograms of cochlear implant candidates.

BACKGROUND: Experimental studies have shown that creating a window in the bony cover of the cochlea and vestibular parts of the inner ear, with preservation of membranous and middle-ear functions, induces an air-bone gap (ABG). This study sought to determine if a similar mechanism explains the ABG frequently observed in audiograms of cochlear implant candidates. METHOD: The study group included 47 candidates for a cochlear implant (94 ears) attending a university-affiliated tertiary medical center who had an ABG component in the audiogram in the absence of external or middle-ear abnormalities. Air- and bone-conduction thresholds on pure-tone audiometry were analyzed for 250 to 8,000 Hz and 250 to 4,000 Hz, respectively. In the 25 patients operated on during the study period, differences in the ABG and in cerebrospinal fluid (CSF) leak were compared between those with and without anomalies on computed tomography. RESULTS: Imaging revealed an abnormal inner-ear structure in 46% of cases, mostly a large vestibular aqueduct, alone or combined with other cochlear or vestibular malformations. ABG was evident over high and low frequencies and was significantly larger at low frequencies and in ears with structural anomalies. A high rate of CSF leak was observed in patients with an ABG and structural anomalies imaging as well as in those with an ABG and normal imaging findings. CONCLUSION: In cochlear implant candidates, the presence of a third window could cause an ABG because of stapes motion-induced shunting of acoustic energy outside the cochlear duct in response to air-conducted stimuli while bone conduction is preserved.