The Effects of Cochlear Dead Regions on Speech Recognition Ability in Patients with Sensorineural Hearing Loss / 听力学及言语疾病杂志

Objective To study the distribution of cochlear dead regions in the cochlea with sensorineural hearing loss (SNHL),and to investigate the effects of cochlear dead regions on speech recognition.Methods A total of 41 SNHL patients (81 ears) were divided into the cochlear dead region group (35 ears) and the group without cochlear dead regions (46 ears) by using threshold equalizing noise test (TEN test).Then we used speech recognition threshold (SRT) and speech discrimination score (SDS) tests to study the distribution of cochlear dead regions and to investigate the effects of cochlear dead regions on speech recognition.Results There were 41 cases (81 ears) sensorineural hearing loss patients and 43.21％ (35/81) were found to have the cochlear dead regions.The cochlear dead region detection rate for patients with mild SNHL was 0(0/11);in patients with moderate SNHL,the cochlear dead region detection rate was 24.1％ (7/29);in patients with severe SNHL the cochlear dead region detection rate was 66.7％ (24/36);the cochlear dead regions of profound SNHL patients were 80.0％ (4/5) respestively.The existence of the cochlear dead regions was significantly correlated with the degree of hearing loss (P＜0.05).The proportion of high frequency cochlear dead regions (16 ears)was much higher than that of the low frequency cochlear dead regions(8 ears).There was no significant reduction of SRT and SDS between high and low cochlear dead regions groups(P＞0.05).The SRT and SDS of the patients with cochlear dead regions were 61.63± 16.76 dB,86.35％±12.03％.The SRT and SDS of the patient with no cochlear dead regions were 75.54 ± 9.56 dB and 64.97％±20.84％.Theresults showed a significant (P＜0.05) reduction of SRT and SDS between the patient with cochlear dead regions and the patient with no cochlear dead regions.Conclusion The greater the degree of hearing loss is,the higher possibility of the existence of cochlear dead regions there is.Cochlear dead regions are common in high frequencies than in low frequencies.The speech recognition ability can be affected.

Early Experience of Non-Linear Frequency Compression Technology in Patients with High-Frequency Hearing Loss / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Consonants are uttered in the high frequency range in speech to bring out understanding of our language. As consonants convey most of the word information, listeners with high-frequency hearing loss find it hard to understand speech. Non-linear frequency compression (NLFC) technology compresses and moves higher frequencies into a lower frequency region where better residual hearing is present. The purpose of this study was to evaluate clinical effectiveness of NLFC technology in patients with high-frequency hearing loss. SUBJECTS AND METHOD: Twelve ears representing patients with sloping, high-frequency sensorineural hearing loss were involved in this study. Pure-tone audiometry and Threshold Equalizing Noise Test were conducted initially in all subjects. The subjects were tested in the counter-balanced order, and had two months of everyday experience with NLFC on/off before testing took place. A resting period intervened the two phases. Performance was repeatedly evaluated with Sound Field Audiometry, Word Recognition Score, Reception Threshold for Sentences and Korean version of International Outcome Inventory for Hearing Aids. RESULTS: Cochlear dead region was detected on 4 kHz of both ears in only one subject. Each subject showed diverse performance and satisfaction with active NLFC condition. Typically, audibility of high-frequency pure-tones improved with NLFC-on condition. However, speech perception both in quiet and noise was not much improved when compared with NLFC-off condition. CONCLUSION: The NLFC technology could improve audibility in high-frequency, but failed to demonstrate benefits regarding speech perception. Further research is needed to validate the effectiveness of the NLFC technology especially in terms of speech intelligibility.

Clinical Application of the Threshold Equalizing Noise Test in Patients with Hearing Loss of Various Etiologies: A Preliminary Study

BACKGROUND AND OBJECTIVES: We aimed to make a preliminary assessment of the prevalence of cochlear dead regions (DRs) and the factors affecting the results of the threshold-equalizing noise (TEN) test in patients with hearing loss of various etiologies. SUBJECTS AND METHODS: Between May and July 2014, 109 patients (191 ears) with hearing loss who visited our outpatient clinic were prospectively enrolled. Pure tone audiometry and TEN (HL) test were performed for all the patients. DR at each frequency was indicated by masked thresholds of > or =10 dB above the TEN level and > or =10 dB above the absolute threshold. RESULTS: DR was present in 15.7% (n=30) of the 191 ears. According to disease entity, 16.6% of patients with sensorineural hearing loss had a DR. However, DR was absent in patients with chronic otitis media. According to audiometric configurations, DR was most common in moderately severe, flat hearing loss. Significantly worse hearing thresholds for both mean hearing level and hearing threshold at each frequency were found in the presence of DR (p<0.001). Logistic regression analysis showed that only the mean hearing level (odds ratio: 1.053, 95% confidence interval: 1.021-1.085) affected the presence of DR. CONCLUSIONS: Although performance of the TEN test is limited by frequencies and hearing levels, it provides additional information regarding DRs and may therefore have the potential to be used as a prognostic tool for diverse diseases causing hearing loss.