Auditory steady-state responses and clinical applications

The auditory steady-state responses to single continuous tones modulated in amplitude have been proposed as an alternative to objective frequency-specific audiometry. The aim of this study was to compare thresholds obtained by pure-tone audiometry (PTA) and by auditory steady-state responses in normal hearing or affected by hearing loss in adults and in order to evaluate the applicability of this objective test in no collaborative hearing-impaired subjects. Eleven people, 6 normal hearing and 5 with hearing loss, underwent PTA and multiple frequency auditory steady-state responses; simultaneous carrier tones (0.5, 1, 2 and 4 KHz) modulated in amplitude at different rates (77–105 Hz) were presented monaurally (TDH 49 earphones) at variable intensities (110–20 dB SPL). The mean threshold difference between PTA and multiple frequency auditory steady-state responses was 28 dB (standard deviation=14.2) and R correlation value at 0.5-1-2-4 kHz was 0.71 (P=0.0012) at the Pearson’s test. These differences were significantly smaller considering the hearing-impaired separately (11.7 dB, standard deviation=2.9). The results of this study confirm previous reports showing that the multiple auditory steady-state response method is an accurate predictor of the behavioural audiogram in patients with sensory-neural hearing impairments and can be used as a valid support for behavioural evaluations.     

Prediction model for hearing outcome in patients with idiopathic sudden sensorineural hearing loss

The aim of this study is to develop a regression model for predicting hearing outcome in patients with idiopathic sudden sensorineural hearing loss (ISSNHL). A total of 174 consecutive patients with ISSNHL (average of the hearing levels at 250, 500, 1,000, 2,000, and 4,000 Hz was ≥40 dB; time from onset to treatment was ≤30 days) were retrospectively analyzed. They received steroid administration (400 mg/day of hydrocortisone sodium succinate followed by tapered doses) in combination with hyperbaric oxygen therapy. The hearing improvement rate compared to the unaffected contralateral ear was calculated. Correlations between the hearing improvement rate and four prognostic factors (patient’s age, days from onset to treatment, initial hearing level, and the presence of vertigo) were examined by simple and multiple regression analyses. In the simple regression analysis, significant correlations were observed between the hearing improvement rate and all four prognostic factors. In the multiple regression analysis, the correlation was significant for patient’s age, days from onset to treatment, and the presence of vertigo with partial correlation coefficients of −0.221, −0.324, and −0.329, respectively, but was not significant for the initial hearing level. We subsequently formulated a multiple regression equation for predicting the hearing improvement rate. The multiple correlation coefficient was 0.495 with a p value of 1.42 × 10⁻⁹. Using this regression model, the hearing improvement rate is still difficult to predict with 95% probability, but is predictable with 70% probability.     

Evaluation of the effects of nonlinear frequency compression on speech recognition and sound quality for adults with mild to moderate hearing loss

Objective: While potentially improving audibility for listeners with considerable high frequency hearing loss, the effects of implementing nonlinear frequency compression (NFC) for listeners with moderate high frequency hearing loss are unclear. The purpose of this study was to investigate the effects of activating NFC for listeners who are not traditionally considered candidates for this technology. Design: Participants wore study hearing aids with NFC activated for a 3–4 week trial period. After the trial period, they were tested with NFC and with conventional processing on measures of consonant discrimination threshold in quiet, consonant recognition in quiet, sentence recognition in noise, and acceptableness of sound quality of speech and music. Study sample: Seventeen adult listeners with symmetrical, mild to moderate sensorineural hearing loss participated. Better ear, high frequency pure-tone averages (4, 6, and 8 kHz) were 60 dB HL or better. Results: Activating NFC resulted in lower (better) thresholds for discrimination of /s/, whose spectral center was 9 kHz. There were no other significant effects of NFC compared to conventional processing. Conclusion: These data suggest that the benefits, and detriments, of activating NFC may be limited for this population.     

Wegener’s granulomatosis presenting with bilateral facial nerve palsy

Primary manifestation of Wegener’s granulomatosis in the mucosa of the middle ear is rather rare, and has been reported as presenting with serous otitis media, chronic otitis media, sensorineural hearing loss, and, in rare instances, unilateral facial palsy. Bilateral facial palsy has never been reported. This last fact constitutes the interest in our report of a 23-year-old female patient who presented with symptoms of recurrent bilateral otitis media, eventually developing sensorineural hearing loss and bilateral facial palsy. Soon thereafter neurological symptoms appeared and lung extension was noted. Histological examination of repeated biopsies taken from the nasal and middle ear mucosa was not conclusive for the suspected disease, and c-ANCA titers were also initially repeatedly negative. Eventually, positive lung biopsy and elevated c-ANCA titers when the patient had developed pulmonary granulomas confirmed the diagnosis of Wegener’s granulomatosis. Mastoid surgery with facial nerve decompression of the most severely afflicted side did not result in the recovery of facial nerve function. Medical therapy with corticosteroids and cyclophosphamide improved the clinical picture but were ineffective in improving the bilateral sensorineural hearing loss and the facial paralysis on the operated side. We would contribute to the literature a unique case of bilateral facial nerve palsy due to Wegener’s granulomatosis. Received: 13 December 2000 / Accepted: 5 February 2001     

Influence of a 6–8 kHz audiometric notch on transient evoked otoacoustic emissions

Thirty-eight patients with known unilateral cochlear hearing loss at 6 and/or 8 kHz were examined for transient evoked otoacoustic emisssions (TEOAEs). These findings were compared with those of the contralateral “normal hearing” ear. Statistically significant lower values of echo reproducibility and amplitude were recorded in hearing-impaired ears, together with a more narrow TEOAE spectrum. In addition to these findings, a globally reduced amplitude of the cochlear response was found that was unrelated to the frequency impaired in pure-tone audiometry (6, 8, or 6–8 kHz). Since patients’ audiometric thresholds at such frequencies could influence test results, findings could possibly be due to an altered echo travelling wave across the most basal part of the cochlea or to coexisting damage in the rest of Corti’s organ that were undetectable with standard audiometry. A significant overlap was found between the results from hearing-impaired ears and those from normally hearing ones. Although TEOAEs were not helpful in the present study in identifying patients with a unilateral hearing loss at 6 and/ or 8 kHz when compared to normal contralateral ears, they are still considered to play an important role in the follow-up of subjects at risk for hearing damage. Received: 22 December 1997 / Accepted: 14 May 1998     

Safety and patient selection of totally implantable hearing aid surgery: Envoy system,Esteem

Patient’s low compliance of conventional hearing aids has lead to innovation of totally implantable hearing devices such as Esteem, Envoy system. This study was designed to evaluate safety of device implantation, patient’s hearing gain, importance of anatomic landmarks, and to describe suitable criteria for patient selection. Via a non-randomized controlled clinical trial, ten patients with moderate-to-severe sensorineural hearing loss were implanted from 2007 to 2009. Mean follow-up period was 29.4 months. Correlation of pre-operative temporal bone CT scan anatomy with postoperative outcome was evaluated. Except one, all other implanted devices are active and patients’ overall average hearing gain are similar to conventional hearing aids (10–22 dB), but patients reported relatively better subjective sound quality compared with their pre-operative conventional hearing aids. One implanted device was explanted in a patient due to facial weakness and low-hearing gain. Revision surgery was done successfully in another patient secondary to excessive bone growth. Totally implantable hearing device surgery seems to be relatively safe and correct patient selection could lead to good outcomes. Lateral location of facial nerve, sclerotic mastoid air cells and narrow facial recess space seems to be related to postoperative complications.     

Vestibular evoked myogenic potentials in Behcet’s disease

The aim of this study was to investigate vestibular evoked myogenic potentials (VEMPs) and their clinical significance in Behcet’s disease. Twenty-six patients with Behcet’s disease and 25 healthy volunteers were evaluated for pure tone audiometry, caloric response, and VEMPs. Sensorineural hearing loss was found in 53.8% of patients with Behcet’s disease, which was significantly higher than controls. Four patients had canal paresis, but no controls; this difference was not significant. Although VEMP recordings were elicited in all study subjects, mean p13 and n23 latencies were prolonged in Behcet’s patients compared with controls. Seven patients had delayed VEMP responses. There were no correlations regarding p13 values and age, duration or activity of disease, vertigo, or sensorineural hearing loss. The results of this preliminary study suggest an association between delayed VEMP responses and Behcet’s disease. Further research with large samples is needed to confirm that VEMP testing is useful to diagnose and follow vestibular dysfunction in Behcet’s disease. This study has been presented at the XXIX. National Otolaryngology Head and Neck Surgery Congress, Antalya, Turkey, May 26–31, 2007. This study was supported by a Baskent University Research Foundation grant (Project No. KA04/188).     

Phase-Locked Responses to Tones of Chinchilla Auditory Nerve Fibers: Implications for Apical Cochlear Mechanics

Responses to tones with frequency ≤ 5 kHz were recorded from auditory nerve fibers (ANFs) of anesthetized chinchillas. With increasing stimulus level, discharge rate–frequency functions shift toward higher and lower frequencies, respectively, for ANFs with characteristic frequencies (CFs) lower and higher than ∼0.9 kHz. With increasing frequency separation from CF, rate–level functions are less steep and/or saturate at lower rates than at CF, indicating a CF-specific nonlinearity. The strength of phase locking has lower high-frequency cutoffs for CFs >4 kHz than for CFs < 3 kHz. Phase–frequency functions of ANFs with CFs lower and higher than ∼0.9 kHz have inflections, respectively, at frequencies higher and lower than CF. For CFs >2 kHz, the inflections coincide with the tip-tail transitions of threshold tuning curves. ANF responses to CF tones exhibit cumulative phase lags of 1.5 periods for CFs 0.7–3 kHz and lesser amounts for lower CFs. With increases of stimulus level, responses increasingly lag (lead) lower-level responses at frequencies lower (higher) than CF, so that group delays are maximal at, or slightly above, CF. The CF-specific magnitude and phase nonlinearities of ANFs with CFs < 2.5 kHz span their entire response bandwidths. Several properties of ANFs undergo sharp transitions in the cochlear region with CFs 2–5 kHz. Overall, the responses of chinchilla ANFs resemble those in other mammalian species but contrast with available measurements of apical cochlear vibrations in chinchilla, implying that either the latter are flawed or that a nonlinear “second filter” is interposed between vibrations and ANF excitation.     

Bimodal benefits in Mandarin-speaking cochlear implant users with contralateral residual acoustic hearing

Abstract

Objective: The present study aimed to measure bimodal benefits and probe their underlying mechanisms in Mandarin-speaking cochlear implant (CI) subjects who had contralateral residual acoustic hearing. Design: The subjects recognised words or phonemes from the Mandarin Lexical Neighborhood Test in noise at a 10-dB signal-to-noise ratio (SNR) with acoustic stimulation, electric stimulation or the combined bimodal stimulation. Study sample: Thirteen Mandarin-speaking subjects wore a CI in one ear and had residual acoustic hearing in the contralateral ear. Six of the subjects (5.2–13.0 years) had pre-lingual onset of severe hearing loss, and seven of them (8.6–45.8 years) had post-lingual onset of severe hearing loss. Results: Both groups of subjects produced a significant bimodal benefit in word recognition in noise. Consonants and tones accounted for the bimodal benefit. The bimodal integration efficiency was negatively correlated with the duration of deafness in the implanted ear for vowel recognition but positively correlated with CI or bimodal experience for consonant recognition. Conclusions: The present results support preservation of residual acoustic hearing, early cochlear implantation and continuous use of bimodal hearing for subjects who have significant residual hearing in the non-implanted ear.     

Brain stem auditory evoked response—A study in parameters

Brain stem audiory evoked response (BAER) audiometry is a non-invasive and objective measure of a subject’s auditory function. The present paper attempts to establish normative data in Indian subjects. It was found that the BAER can detect asymptomatic high frequency hearing losses. Wave V’s threshold, latency and amplitude, along with comparisons between the auditory (subjective) and BAER threshold, are useful parameters in testing for organic and non-organic hearing disorders.     

Cochlear implant in Cogan’s syndrome

Post-lingual deafness is a stressful condition which is rendered even more painful by the sudden emotional isolation that the patient suffers. Cogan’s syndrome is a rare autoimmune cause for post-lingual deafness characterized by non-syphilitic interstitial keratitis, bilateral audio vestibular deficiencies and systemic vasculitis. World over very few cases of Cogan’s syndrome have been reported. Cochlear implant surgery in such a patient is a challenging but highly satisfactory experience due to the multitude of clinical problems the patient faces. This demands a proper work up, meticulous surgery and stringent post-operative follow-up. Here we present a patient with atypical Cogan’s syndrome, diabetes mellitus and hypothyroidism. She went into a major depression with suicidal tendency following the complete loss of hearing. We performed cochlear implant surgery in this patient, but not before facing several clinical obstacles, helped by a dedicated team consisting of a rheumatologist, endocrinologist, neurophysician, psychiatrist, anaesthetists and audiologist. The results are extremely satisfying for the patient and all the people involved. This case underlines the prime importance of hearing in maintaining the psychological well being of a human being.     

Impact of frequency compression on music perception

Objective: To determine the effects of frequency compression on music perception, and the impact of previous music training and hearing status. It was hypothesized that lesser amounts of compression would be preferred, and that this pattern of preference would be more evident in the musically trained groups. Design: A paired-comparison paradigm was used. Subjects listened to pairs of musical passages as processed by a hearing aid with different frequency-compression settings. Subjects indicated their preferred passage and the strength of their preference. Study sample: Fifty-seven subjects divided in four groups, according to hearing status (normal hearing, mild-to-moderate hearing loss), and previous music experience (trained, not trained). Results: Subjects generally preferred the conditions with the lesser amount of compression. Listeners in the group with previous music training showed stronger preference for less compression than those without training, as did listeners with normal hearing when compared to subjects with hearing loss. Conclusions: Although less frequency compression was in general preferred, there was more variability in the comparisons involving the default settings for a 50-dB hearing loss (i.e. start frequency 4000 Hz, compression ratio 2.5:1) and no compression, suggesting that mild amounts of compression may not be detrimental to perceived sound quality.     

Dexamethasone base conserves hearing from electrode trauma-induced hearing loss

Objective/Hypothesis: Local treatment of the cochlea after electrode insertion trauma with dexamethasone base conserves hearing against trauma‐induced loss. Study Design: Laboratory animal study. Methods: A guinea pig model of electron insertion trauma (EIT)‐induced hearing loss (HL) used 44 guinea pigs sub‐divided into four groups: 1) unoperated, controls (Controls, n = 44); 2) EIT, untreated (EIT, n = 15); 3) EIT plus artificial perilymph (EIT + AP, n = 15); and 4) EIT plus dexamethasone base (EIT + DXMb, n = 14). Cochleae that received EIT were randomly selected with contralateral, unoperated cochleae as internal controls. Auditory brainstem responses (ABRs) in response to 0.5 to 16 kHz pure tones were obtained before surgery, immediately after surgery (0 day), and on post‐EIT days 3, 7, 14, and 30. Hair cell counts were obtained from stained organ of Corti specimens from all four groups (n = 3/group). Data were analyzed using analysis of variance and a Tukey‐Kramer honestly significant difference post hoc test with significance alpha set at <0.05 (hearing) and <0.001 (hair cells). Results: There were significant differences (<0.05) between the ABR thresholds of unoperated (control) and contralateral operated (experimental) ears of EIT and of EIT + AP groups for all tested frequencies. There was no statistical difference (>0.05) in ABR thresholds in the EIT + DXMb versus control groups for 0.5 to 4 kHz tones. DXMb treatment protected hair cells from EIT‐induced damage and loss while AP treatment did not. Conclusion: The absence of significant differences in hearing thresholds between the EIT + DXMb group and control ears in response to 0.5 to 4 kHz tones demonstrates that DXMb is as effective as the aqueous form of dexamethasone in conserving hearing against EIT‐induced loss.     

Hearing benefit in middle ear reconstructive surgery: A comparative study of the current methods

The objective of this prospective study was to compare two methods of predicting the level of hearing benefit following reconstructive middle ear surgery, namely Glasgow benefit plot and Belfast rule of thumb. The correlation of hearing benefit as measured by using these methods was also compared with patient’s self-assessment of his/her hearing status. Sixty patients undergoing middle ear reconstructive surgery were studied. Hearing status was assessed pre and post operatively by pure tone audiometry and self-assessment by patient with a questionnaire. The accuracy of predictability of hearing benefit by the two methods was compared with the patient’s own assessment. Relevant literature on the subject is reviewed.     

Sensorineural hearing loss in patients with chronic otitis media

Chronic otitis media is generally associated with some degree of hearing loss, which is often the patient’s chief complaint. This hearing loss is usually conductive, resulting from tympanic membrane rupture and/or changes in the ossicular chain due to fixation or erosion caused by the chronic inflammatory process. When cholesteatoma or granulation tissue is present in the middle ear cleft, the degree of ossicular destruction is even greater. An issue that has recently gained attention is additional sensorineural hearing loss due to chronic otitis media. While the conductive loss can be minimized through surgery, sensorineural hearing loss constitutes a permanent after effect, attenuated only through the use of a hearing aid. However, a few groups have reported a decrease in sensorineural function in these patients as well. This survey study performed at a referral center evaluates the occurrence of sensorineural hearing loss in ambulatory patients with this disease. We reviewed the files of patients with unilateral chronic otitis media. One hundred and fifty patients met the inclusion criteria: normal otoscopy and normal hearing in the contralateral ear. Main outcome measure: bone-conduction threshold averages were calculated for frequencies of 500, 1,000, 2,000, 3,000 and 4,000 Hz, with comparison between the normal ear and the ear with chronic otitis media. Thresholds were examined separately for each frequency. The bone-conduction threshold averages for the normal side were lower than those for the ear with chronic otitis media. The threshold shift was statistically significant for each frequency (P < 0.0001, Student’s t test). There were differences between the groups when analyzed for age (500 and 1,000 Hz) or the presence of cholesteatoma (1,000 Hz). This study shows that chronic otitis media is associated with a decrease in cochlear function.     

Personality and experimentally simulated hearing loss

Previous studies have suggested that personality factors may affect responses of the normally hearing and those with organic or non-organic hearing losses in audiological assessments. Audiometrically naive (n = 15) and sophisticated (n = 15) subjects who took part in a study of experimentally simulated hearing loss completed the Eysenck Personality Inventory in order that the relationship between personality dimensions and responses on audiometric tests could be investigated for all subjects and for males and females separately. The finding that more anxious males were less able to match pure tone losses with losses for speech suggests that differences in responses of male and female subjects to audiometric tests should be investigated, particularly in view of the preponderance of male subjects in studies of nonorganic hearing loss. A relationship between extraversion and correct speech responses on retest for the sophisticated subjects was thought to reflect abandonment of their strategies in the difficult task of matching hearing loss for speech with that for pure tones. No discernible trends were evident from the remaining analyses.     

广东地区聋儿助听器验配情况分析

目的：探讨广东省内不同经济发展水平地区聋儿助听器验配特点与社会经济发展水平的相关性.方法：选取广东地区常住居民家庭中首次配戴助听器的聋儿,按其家庭常居住地的社会经济发展水平的差异,分为经济较为发达的珠江三角洲地区（包括广州、深圳、珠海、佛山、东莞、中山）和经济相对欠发达的广东其他地区两大组,分别比较其第1次助听器验配时的年龄及性别比例、耳聋程度和助听器种类（数码/模拟）的选择.结果：①广东地区第1次配戴助听器聋儿的平均年龄为3.82岁,男、女比例为1.47：1,地区间差异不明显;②珠江三角洲地区第1次配机时残余听力听性脑干诱发电位Ⅴ波阈值超过90dBnHL的聋儿比例为86.36%,广东其他地区为93.85%,远比珠江三角洲地区高;③珠江三角洲地区第1次配戴助听器时选择数码助听器的聋儿为75.57%,广东其他地区为65.38%.结论：聋儿助听器验配特点与当地的社会经济发展水平密切相关;广东地区配戴助听器聋儿的男、女性别比例存在巨大差异,有待进一步探讨.     

Binaural loudness summation in the hearing impaired

Binaural loudness summation was measured using three different paradigms with 10 normally hearing and 20 bilaterally symmetrical high-frequency sensorineural hearing loss subjects. An adaptive paradigm and a loudness matching procedure measured summation at the lower and upper level of comfortable loudness and the loudness discomfort level (LDL). Monaural and binaural LDLs also were obtained with a clinical procedure designed to select maximum output of hearing aids. Stimuli for all three tasks consisted of 500- and 4000-Hz pure tones and a speech spectrum noise. Binaural summation increased with presentation level using the loudness matching procedure, with values in the 6-10 dB range. Summation decreased with level using the adaptive paradigm, and no summation was present with the clinical LDL task. The hearing-impaired subjects demonstrated binaural summation that was not significantly different from the normally hearing subjects. The results suggest that a bilaterally symmetrical sensorineural hearing loss does not affect binaural loudness summation. The monaural and binaural dynamic range widths were similar, and the LDL results suggest that binaural loudness summation may not be an important factor in selecting maximum output of hearing aids.     

The CON-SOT-LOT test for nonorganic hearing loss

The efficacy of a screening procedure for detecting nonorganic hearing loss using standard audiometric instrumentation was examined. Thirty normal-hearing subjects' responses to continuous and standard and lengthened off-time pulsed tones, using an ascending-descending method, were compared. Subjects were asked to respond to test stimuli in normal-hearing and simulated hearing loss conditions. Data show that there are clinical and statistical differences between subjects' response patterns in the normal-hearing condition as compared to the feigned hearing loss condition. The procedure is offered as a simple method of screening for nonorganic hearing loss.     

Talker separation and sequential stream segregation in listeners with hearing loss: patterns associated with talker gender.

The purpose of this paper was to examine the relations between the ability to separate simultaneous sentences spoken by talkers of different gender and the ability to separate pitch patterns in a sequential stream segregation task. Simultaneous sentence pairs consisting of 1 sentence spoken by a male talker and 1 sentence spoken by a female talker were presented to 11 listeners with sensorineural hearing loss. Listeners were asked to repeat both sentences and were scored on the number of words repeated correctly. Separate scores were obtained for the male and female sentences. Sequential stream segregation was then measured using series of tones consisting of a fixed frequency (A) and a varying frequency tone (B). Tone series were presented in an ABA_ABA_... pattern starting at a varying frequency either below (ascending pattern) or above (descending pattern) the frequency of the fixed 1000 Hz tone. Fusion thresholds, defined as the frequency separation at which listeners could no longer perceptually separate the tones A and B, were obtained for both ascending and descending patterns. There was no significant difference between ascending and descending fusion thresholds based on the group data, but substantial individual differences were observed. Speech recognition scores for the male talker were strongly related to ascending fusion thresholds, but not descending thresholds. In contrast, speech recognition scores for the female talker were strongly related to the descending thresholds, but not the ascending thresholds. For both the male and female talkers, better recognition scores were associated with lower (nearer to normal) fusion thresholds. Results suggest that the importance of streaming in the perceptual separation of talkers may depend on the nature of the information provided by the changing pitch stream.