Audiometric predictions using stimulus-frequency otoacoustic emissions and middle ear measurements

OBJECTIVE: The goals of the study are to determine how well stimulus-frequency otoacoustic emissions (SFOAEs) identify hearing loss, classify hearing loss as mild or moderate-severe, and correlate with pure-tone thresholds in a population of adults with normal middle ear function. Other goals are to determine if middle ear function as assessed by wideband acoustic transfer function (ATF) measurements in the ear canal account for the variability in normal thresholds, and if the inclusion of ATFs improves the ability of SFOAEs to identify hearing loss and predict pure-tone thresholds. DESIGN: The total suppressed SFOAE signal and its corresponding noise were recorded in 85 ears (22 normal ears and 63 ears with sensorineural hearing loss) at octave frequencies from 0.5 to 8 kHz, using a nonlinear residual method. SFOAEs were recorded a second time in three impaired ears to assess repeatability. Ambient-pressure ATFs were obtained in all but one of these 85 ears and were also obtained from an additional 31 normal-hearing subjects in whom SFOAE data were not obtained. Pure-tone air and bone conduction thresholds and 226-Hz tympanograms were obtained on all subjects. Normal tympanometry and the absence of air-bone gaps were used to screen subjects for normal middle ear function. Clinical decision theory was used to assess the performance of SFOAE and ATF predictors in classifying ears as normal or impaired, and linear regression analysis was used to test the ability of SFOAE and ATF variables to predict the air conduction audiogram. RESULTS: The ability of SFOAEs to classify ears as normal or hearing impaired was significant at all test frequencies. The ability of SFOAEs to classify impaired ears as either mild or moderate-severe was significant at test frequencies from 0.5 to 4 kHz. SFOAEs were present in cases of severe hearing loss. SFOAEs were also significantly correlated with air conduction thresholds from 0.5 to 8 kHz. The best performance occurred with the use of the SFOAE signal-to-noise ratio as the predictor, and the overall best performance was at 2 kHz. The SFOAE signal-to-noise measures were repeatable to within 3.5 dB in impaired ears. The ATF measures explained up to 25% of the variance in the normal audiogram; however, ATF measures did not improve SFOAEs predictors of hearing loss except at 4 kHz. CONCLUSIONS: In common with other OAE types, SFOAEs are capable of identifying the presence of hearing loss. In particular, SFOAEs performed better than distortion-product and click-evoked OAEs in predicting auditory status at 0.5 kHz; SFOAE performance was similar to that of other OAE types at higher frequencies except for a slight performance reduction at 4 kHz. Because SFOAEs were detected in ears with mild to severe cases of hearing loss, they may also provide an estimate of the classification of hearing loss. Although SFOAEs were significantly correlated with hearing threshold, they do not appear to have clinical utility in predicting a specific behavioral threshold. Information on middle ear status as assessed by ATF measures offered minimal improvement in SFOAE predictions of auditory status in a population of normal and impaired ears with normal middle ear function. However, ATF variables did explain a significant fraction of the variability in the audiograms of normal ears, suggesting that audiometric thresholds in normal ears are partially constrained by middle ear function as assessed by ATF tests.     

Long-term measurement of binaural intensity matches and pitch matches. I. Normal hearing

Changes in pitch perception and hearing thresholds over time have been observed in subjects with monaural fluctuating low-frequency hearing loss and Ménière's disease. Long-term suprathreshold audiometry and binaural pitch matches could provide information of these changes. Ten normal subjects were tested for stability of binaural intensity and pitch matches during 9–22 days in their homes with newly developed portable test equipment. Binaural pitch matches were measured using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear. The results showed stable binaural intensity matches (individual inter-quartile ranges, IQRs, 1.2 to 5.7 dB), but binaural pitch matches varied greatly (IQR ?0.6 to 5.3% at 0.25 kHz; IQR ?1.6 to 7.9% at 1 kHz). Binaural pitch-matching was much better in subjects who could define pitch precisely during monaural pitch matching. It was concluded that in future long-term evaluations of patients with fluctuating inner-ear function, binaural intensity matches could be suitable for all, but binaural pitch matching only for selected patients.     

Long-term measurement of binaural intensity matches and pitch matches. I. Normal hearing

Changes in pitch perception and hearing thresholds over time have been observed in subjects with monaural fluctuating low-frequency hearing loss and Ménière's disease. Long-term suprathreshold audiometry and binaural pitch matches could provide information of these changes. Ten normal subjects were tested for stability of binaural intensity and pitch matches during 9-22 days in their homes with newly developed portable test equipment. Binaural pitch matches were measured using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear. The results showed stable binaural intensity matches (individual inter-quartile ranges, IQRs, 1.2 to 5.7 dB), but binaural pitch matches varied greatly (IQR -0.6 to 5.3% at 0.25 kHz; IQR -1.6 to 7.9% at 1 kHz). Binaural pitch-matching was much better in subjects who could define pitch precisely during monaural pitch matching. It was concluded that in future long-term evaluations of patients with fluctuating inner-ear function, binaural intensity matches could be suitable for all, but binaural pitch matching only for selected patients.     

正常听力耳鸣患者听尼特TM检测及高刺激率听觉脑干反应结果及分析

目的 观察正常听力耳鸣患者的耳鸣音调、响度、掩蔽曲线及高刺激率听觉脑干反应(ABR)检测结果，探讨耳鸣的临床特征及发病机制。方法 选取162例正常听力耳鸣患者，对其进行耳鸣音调、响度匹配，同时选取其中140例单侧耳鸣患者，对140患耳与对侧140健耳，分别进行高、低刺激率ABR检测，比较不同刺激率下PL差值(△PL)、IPL差值(△IPL)。结果 听力正常耳鸣的耳鸣音调分布从125～8000Hz，以4000～8000Hz高频为主；耳鸣响度从0～20dB，5～10dB最多；佛德曼曲线以汇聚型为主；患耳与健侧耳高、低刺激率ABR Ⅰ～Ⅴ △IPL差值＞0.28ms的耳数分别为16耳及12耳，差值无显著意义(P＞0.05)。结论 总结162例听力正常耳鸣患者的临床特征，为进一步的临床诊疗提供依据；耳鸣起源于内耳微循环障碍的理论不适用于解释正常听力耳鸣患者，耳鸣产生的机制可能不能用单一的理论解释。     

Functional hearing loss and its relationship to resolved hearing levels

The nature of functional hearing loss was retrospectively studied with respect to hearing sensitivity after resolution of the nonorganic components in 63 adults with bilateral exaggerated losses (126 ears). The configuration of the functional components (difference between the functional and resolved thresholds) was found to be related to that of the resolved hearing levels. The size of the functional overlay was essentially the same across the audiometric frequency range when the hearing was actually normal or if there was only mild loss. In cases of precipitously sloping high-frequency losses, the magnitude of the functional overlay became dramatically smaller for the impaired frequencies than for lower frequencies where hearing was normal or only mildly impaired. Moderate and severe losses represented a transitional situation, in which the functional components became gradually smaller with increasing frequency. Subjects with different resolved hearing in each ear (e.g., mild loss in one ear and a precipitous loss in the other) demonstrated nonorganic overlays that were consistent with the actual hearing levels for each respective ear. The findings suggest the use of an internalized, loudness level-based anchor by subjects with functional losses: the test signal must sound as loud as the anchor at each frequency in order for an exaggerated threshold response to be volunteered at that respective frequency. The pure-tone audiometric configuration and amount of functional loss at least in bilateral cases is thus consistently accounted for on the basis of known and explainable auditory factors.     

Tinnitus loudness matchings in relation to annoyance and grading of severity

OBJECTIVE: To measure and compare different parameters of tinnitus loudness obtained via matching and to investigate their associations with self-reported severity of tinnitus. METHODS: From the audiology department 18 patients with unilateral tinnitus of sensorineural origin were selected. They underwent pure-tone audiometry, and in a matching paradigm their tinnitus pitch was estimated. Loudness was assessed at tinnitus frequency and at the frequency of best hearing and both were expressed in sensation level (SL) and hearing level (HL). Moreover, minimal masking level (MML) with white noise was assessed as well as thresholds for the tinnitus tone and a comparison tone in the contralateral ear when tinnitus was masked. RESULTS: Annoyance and grading of severity were associated with measures of loudness expressed in HL, MML, and pure-tone audiometry. Loudness in SL was not associated with self-reported severity. Tinnitus loudness, matched at the frequency of best hearing instead of the tinnitus frequency, appears to be less dependent on HL, while still being associated with distress and grading of severity. CONCLUSION: Severity of tinnitus is related to hearing thresholds, and loudness in SL provides little clinically useful information.     

Hearing impairment and tinnitus pitch in patients with unilateral tinnitus: comparison of sudden hearing loss and chronic tinnitus

OBJECTIVES: The objectives were to analyze the results of pitch-matching and loudness-balance testing in patients with unilateral tinnitus and to evaluate the relationship between audiological findings based on the tinnitus-affected and tinnitus-unaffected threshold differences and tinnitus pitch by using linear interpolation methods. In addition, the effects of the duration of the tinnitus on this relationship were investigated. Sudden sensorineural hearing loss with tinnitus was selected for the "acute tinnitus" group, and unilateral tinnitus with unknown disease and a duration of more than 3 months was selected for the "chronic tinnitus" group. STUDY DESIGN: Retrospective study of the clinical records of patients. METHODS: One hundred thirty-two patients with unilateral tinnitus (comprising 68 female [51.5%] and 64 male [48.5%] patients) were investigated as subjects. Their mean age was 50.4 years (SD = 15.8 y). All patients underwent otoneurological testing, including the pure-tone audiogram and pitch-matching and loudness-balance tests. RESULTS: The mean difference in the hearing threshold between the tinnitus-affected ear and the tinnitus-unaffected ear was largest near the tinnitus pitch in both the acute and the chronic tinnitus groups. However, the relationship between hearing impairments and tinnitus pitch was somewhat different in the two groups: It exhibited a single smooth peak in the acute tinnitus group but a bimodal peak in the chronic tinnitus group. CONCLUSION: The results suggest that tinnitus is related to hearing impairment in the same frequency region in patients with sudden sensorineural hearing loss with tinnitus or in patients with chronic tinnitus, whereas some instances of chronic tinnitus are caused by reorganization in cortical cells.     

听力宝A PP与纯音听力计测听结果的比较

目的 评估应用自我测试听力的听力宝APP测听的准确性及可行性.方法 43例(86耳)志愿者,年龄18～70岁,平均40.9±14.5岁,男22例,女21例,其中听力正常35耳,听力损失51耳.首先,每位受试者采用听力宝APP测试软件在噪声小于30 dB A的隔声室环境下自己进行0.125、0.25、0.5、1、2、4、...     

急性低频感音神经性聋镫骨肌声反射消失的病因及临床意义探讨

目的 探讨部分急性低频感音神经性聋(acute low-tone sensorineural hearing loss,ALHL)镫骨肌声反射(acoustic stapedius reflex,AR)消失的原因及临床意义.方法 分析21例(21耳)镫骨肌声反射消失的ALHL患者患耳的声顺值、共振频率、耳蜗电图、DPOAE及ABR的改变,与其健耳以及镫骨肌声反射正常的ALHL患者相应观察值进行对照,并比较患耳上述观察值治疗前后的变化.结果 ALHL镫骨肌声反射消失耳的病变在内耳,其共振频率略高于健耳及对照组,但无显著性差异.患耳耳蜗电图-SP/AP值高于健耳及对照组,差异显著.糖皮质激素及利尿剂治疗后,听力恢复正常16耳,其中仅4耳AR可引出,12耳仍不能引出;其余5耳听力仅部分恢复,AR仍不能引出.结论 膜迷路积水导致镫骨底板活动受限是AR消失的重要原因之一,膜迷路积水同时引起传声系统质量及劲度的改变,其对共振频率的影响取决于积水对镫骨底板活动度的影响程度.     

Informational Masking in Normal-hearing and Hearing-impaired Listeners

The present study aimed to test whether central, across-channel, informational auditory processing abilities are altered by hearing loss. The informational masking effect exerted on a 1 kHz tone-pip by a simultaneous four-tone masker, whose spectral content changed within as well as across trials, was measured in the left and right ears of normal-hearing subjects and hearing-impaired subjects with either symmetrical or asymmetrical hearing loss between the two ears. In the subjects with normal-hearing or symmetrical hearing loss, the level of the masker was set to 40 dB SL in each ear, in the subjects with asymmetrical hearing loss, the masker was set to 40 dB SL in the best ear and loudness-balanced in the other ear. The results failed to reveal significant differences in informational masking between normal-hearing and hearing-impaired subjects. However, in subjects with asymmetric hearing loss, less informational masking was observed in the ear with the more elevated absolute thresholds than in the opposite ear. Since the latter finding can be explained in terms of across-ear differences in loudness recruitment, it is suggested that central, across-channel, informational processing abilities are not substantially different in hearing-impaired than in normal-hearing ears.     

Informational masking in normal-hearing and hearing-impaired listeners

The present study aimed to test whether central, across-channel, informational auditory processing abilities are altered by hearing loss. The informational masking effect exerted on a 1 kHz tone-pip by a simultaneous four-tone masker, whose spectral content changed within as well as across trials, was measured in the left and right ears of normal-hearing subjects and hearing-impaired subjects with either symmetrical or asymmetrical hearing loss between the two ears. In the subjects with normal-hearing or symmetrical hearing loss, the level of the masker was set to 40 dB SL in each ear, in the subjects with asymmetrical hearing loss, the masker was set to 40 dB SL in the best ear and loudness-balanced in the other ear. The results failed to reveal significant differences in informational masking between normal-hearing and hearing-impaired subjects. However, in subjects with asymmetric hearing loss, less informational masking was observed in the ear with the more elevated absolute thresholds than in the opposite ear. Since the latter finding can be explained in terms of across-ear differences in loudness recruitment, it is suggested that central, across-channel, informational processing abilities are not substantially different in hearing-impaired than in normal-hearing ears.     

Temporal modulation transfer functions for band-limited noise in subjects with cochlear hearing loss.

The modulation depth required for the detection of sinusoidal amplitude modulation was measured as a function of modulation rate, giving temporal modulation transfer functions (TMTFs). The carrier was a one-octave wide noise centred at 2 kHz, and it was presented in an unmodulated background noise lowpass filtered at 5 kHz. Three subjects with unilateral cochlear hearing loss were tested. For each subject, the normal ear was tested both at the same sound pressure level (SPL) and at the same sensation level (SL) as the impaired ear. The TMTFs were essentially the same for the normal and impaired ears, both at equal SPL and at equal SL. The better ears of three subjects with bilateral cochlear losses were also tested. Again, TMTFs were essentially the same as obtained for normal ears. These results suggest that temporal resolution is not necessarily adversely affected by cochlear hearing loss, at least as measured by this task.     

Dichotic sentence identification test in Portuguese: a study in young adults

IntroductionAmong the currently-applied auditory processing tests, dichotic listening tests have been widely used, since they allow investigating the hemispheric and inter-hemispheric function and their respective skills to process the received auditory information.ObjectiveTo obtain normality reference measures with the new dichotic sentence identification test in right-handed adults with normal hearing.MethodsQuantitative, observational, cross-sectional study. 72 subjects were assessed, aged 19–44 years, right-handed, with normal hearing, without hearing complaints. The dichotic sentence identification test consists of different lists of sentences, which were combined two by two and presented at the same time, using earphones in both ears, at 50 dB Sensation Level. The test was applied in four stages: training of the 3 stages, free attention, right and left directed attention, thus evaluating different auditory skills.ResultsIn the free attention task, the average percentage of correct answers in the right ear was 93.59% and in the left ear 86.06%, with a statistically significant difference between the ears, with an advantage for the right ear. In the directed attention task, the average percentage of correct answers was 99.37% in the right ear and 98.8% in the left ear, with no statistical difference between the ears.ConclusionIt is suggested, as a normality reference for the stage of free attention, 90%–100% for correct answers for the right ear and for the left ear, from 80% to 100%. When there is asymmetry between the ears, differences of up to 20% are expected, with an advantage for the right ear For the directed attention stage, the expected normality reference values ??are 100% for the right ear and for the left ear, with no asymmetry between the ears; however, if it occurs, a difference of 10% is expected between the ears, with an advantage for the right ear.     

Two Ears Are Not Always Better than One: Mandatory Vowel Fusion Across Spectrally Mismatched Ears in Hearing-Impaired Listeners

Hearing loss and auditory prostheses can alter auditory processing by inducing large pitch mismatches and broad pitch fusion between the two ears. Similar to integration of incongruent inputs in other sensory modalities, the mismatched, fused pitches are often averaged across ears for simple stimuli. Here, we measured parallel effects on complex stimulus integration using a new technique based on vowel classification in five bilateral hearing aid users and eight bimodal cochlear implant users. Continua between five pairs of synthetic vowels were created by varying the first formant spectral peak while keeping the second formant constant. Comparison of binaural and monaural vowel classification functions for each vowel pair continuum enabled visualization of the following frequency-dependent integration trends: (1) similar monaural and binaural functions, (2) ear dominance, (3) binaural averaging, and (4) binaural interference. Hearing aid users showed all trends, while bimodal cochlear implant users showed mostly ear dominance or interference. Interaural pitch mismatches, frequency ranges of binaural pitch fusion, and the relative weightings of pitch averaging across ears were also measured using tone and/or electrode stimulation. The presence of both large interaural pitch mismatches and broad pitch fusion was not sufficient to predict vowel integration trends such as binaural averaging or interference. The way that pitch averaging was weighted between ears also appears to be important for determining binaural vowel integration trends. Abnormally broad spectral fusion and the associated phoneme fusion across mismatched ears may underlie binaural speech perception interference observed in hearing aid and cochlear implant users.     

89例瞬态声诱发耳声发射筛查未通过婴幼儿听力学特点分析

目的 探讨听力筛查未通过而短声(click)诱发听性脑干反应阈值正常婴幼儿的听力学特点,进一步分析畸变产物耳声发射(DPOAE)不同频率异常与其他客观听力检查异常之间的关系.方法 瞬态声诱发耳声发射(TEOAE)听力筛查未通过而接受包括DPOAE、短声ABR、40 Hz听觉相关电位、226 Hz声导抗、1000 Hz声导抗和声反射等诊断性听力学检查的患儿共695例,以其中诊断性短声诱发ABR阈值正常的新生儿及婴幼儿89例(123耳)作为研究对象,根据DPOAE频率异常的不同分为A组(全频正常)、B组(低频异常)、C组(高频异常)和D组(全频异常).对比各项听力检查结果,分析DPOAE频率异常各组与其他5项客观听力检查(ABR Ⅰ波潜伏期、40 Hz听觉相关电位、226 Hz鼓室声导抗、1000 Hz鼓室声导抗及声反射)之间的相互关系.结果 123耳中所有6项听力检查均正常者7耳(5.7%);6项听力检查中有一项或一项以上异常者116耳(94.3%).男婴的异常率为93.9%(77/82),女婴的异常率为95.1%(39/41),二者差异无统计学意义(P＞0.05);左耳异常率为93.1%(54/58),右耳异常率为95.4%(62/65),二者差异无统计学意义(P＞0.05).各组耳数所占比例由高到低分别是D组48.0%(59/123)、B组27.6%(34/123)、A组16.3%(20/123)和C组8.2%(10/123).A组、B组和D组中异常率最高的检查项目均为声反射,异常率分别为40.0%,55.9%和66.1%;而C组中异常率最高的项目为ABR Ⅰ波潜伏期(50.0%).各组低频听力损失均以轻度为主,在B组中有1耳为中度听力损失,D组中有6耳为中度听力损失,1耳为重度听力损失.结论 听力筛查未通过而短声ABR反应阈值正常的婴幼儿,如果DPOAE全频异常,需要及时进行全面的听力学评估,而DPOAE全频正常、低频异常或高频异常者,需要进行跟踪随访.

Abstract：

Objective The presnt study was to evaluate the audiological characteristics of infants with normal auditory brainstem response thresholds in click and abnormal transiently evoked otoacoustic emissions. Relationships between test results of distortion product otoacoustic emissions(DPOAE) and other hearing testing methods were also evaluated. Methods The participants consisted of eighty-nine infants,with a total of 123 ears. All participants' TEOAE screening results were abnormal but diagnostic click ABR results were normal. The participants were classified into the following goups based on the test results from distortion product otoacoustic emissions: group A (normal all-frequency ), group B (abnormal lowfrequency), group C (abnormal high-frequency ), and group D (abnormal all-frequency ). Results Obtained from these groups were compared to results of other hearing tests including the latency of ABR wave Ⅰ, 40 Hz auditory event related potential (40 Hz AERP), 226 Hz and 1000 Hz tympanometry, and acoustic reflex. Results In six hearing tests in the 123 ears, seven ears (5.7%) were normal, while 116ears (94. 3% ) were abnormal. No significantly differences were detected between boys (93.9%) and girls (95. 1% ), as well as between left (93. 1% ) and right ears (95.4%). The proportion of abnormal test results ranked as follows: 59 ears in group D (48.0%), 34 ears in group B (27.6%), 20 ears in group A (16. 3% ), and 10 ears in group C (8.2%). The highest abnormal rates in groups A, B and D were acoustic reflex, which were 40. 0% for group A, 55.9% for group B and 66. 1% for group D respectively.The highest abnormal rate in group C was the latency of ABR wave Ⅰ ( 50. 0% ). Distribution of lowfrequency hearing loss in each group was mainly mild. However, one ear in group B was moderate hearing loss, six ears in group D were moderate hearing loss, and one ear in group D was severe hearing loss.Conclusions The present study showed that, of which infants with normal thresholds of ABR failed the hearing screening, comprehensively audiology assessment is needed. And of which infants with normal DPOAE in full frequency or abnormal in high frequency region or low frequency region need to be followed up.     

Frequency discrimination in ears with and without contralateral cochlear dead regions

Abstract

Objective: The purpose of this study was to test the ability to discriminate low-frequency pure-tone stimuli for ears with and without contralateral dead regions, in subjects with bilateral high-frequency hearing loss; we examined associations between hearing loss characteristics and frequency discrimination of low-frequency stimuli in subjects with high-frequency hearing loss. Design: Cochlear dead regions were diagnosed using the TEN-HL test. A frequency discrimination test utilizing an adaptive three-alternative forced choice method provided difference limens for reference frequencies 0.25 kHz and 0.5 kHz. Study sample: Among 105 subjects with bilateral high-frequency hearing loss, unilateral dead regions were found in 15 subjects. These, and an additional 15 matched control subjects without dead regions, were included in the study. Results: Ears with dead regions performed best at the frequency discrimination test. Ears with a contralateral dead region performed significantly better than ears without a contralateral dead region at 0.5 kHz, the reference frequency closest to the mean audiogram cut-off, while the opposite result was obtained at 0.25 kHz. Conclusions: Results may be seen as sign of a contralateral effect of unilateral dead regions on the discrimination of stimuli with frequencies well below the audiogram cut-off in adult subjects with bilateral high-frequency hearing loss.     

Detecting the recruitment phenomenon in adults using 80-Hz auditory steady-state response

ObjectivesThe ASSR is used widely as an objective measurement of hearing in clinical settings because of its high frequency specificity. The recruitment phenomenon is generally detected using subjective evaluations which require direct communication with the patient. If the recruitment phenomenon can be detected with ASSR, it would facilitate diagnosis in patients with developmental disorders and infants.Subjects and methodsWe examined 2 groups of subjects: 10 subjects with unilateral hearing impairment in whom the recruitment phenomenon was detected by the alternate binaural loudness balance test and 12 normal subjects. We compared the relationships between the ASSR response and the stimulus sound pressure level in the 2 groups using the 80-Hz ASSR.ResultsThe amplitude of ASSR was significantly higher in the impaired ear in hearing-impaired subjects compared to a normal ear in normal subjects. The latency of ASSR was significantly shorter in the impaired ear in hearing-impaired subjects than in the normal ear in the normal subjects.ConclusionThis study showed that the recruitment phenomenon caused the higher amplitude and the shorter latency observed in hearing-impaired subjects in the 80-Hz auditory steady-state response (ASSR) in comparison with normal subjects.     

A potential neurophysiological correlate of electric-acoustic pitch matching in adult cochlear implant users: Pilot data

The overall goal of this study was to identify an objective physiological correlate of electric-acoustic pitch matching in unilaterally implanted cochlear implant (CI) participants with residual hearing in the non-implanted ear. Electrical and acoustic stimuli were presented in a continuously alternating fashion across ears. The acoustic stimulus and the electrical stimulus were either matched or mismatched in pitch. Auditory evoked potentials were obtained from nine CI users. Results indicated that N1 latency was stimulus-dependent, decreasing when the acoustic frequency of the tone presented to the non-implanted ear was increased. More importantly, there was an additional decrease in N1 latency in the pitch-matched condition. These results indicate the potential utility of N1 latency as an index of pitch matching in CI users.     

Tympanometric findings in patients with enlarged vestibular aqueducts

OBJECTIVES: The purpose of this study was to study systematically some relationships between the resonance frequency of the middle-ear transmission system and the volume of the endolymphatic duct and sac in patients with an enlarged vestibular aqueduct (EVA). STUDY DESIGN: Prospective study. METHODS: Thirteen patients (24 ears) with EVA, 17 subjects (29 ears) with normal hearing, and 17 patients (21 ears) with sensorineural hearing loss without EVA served as experimental subjects. Standard pure-tone audiometry, standard clinical tympanometry (using a 226-Hz probe tone), and multifrequency tympanometry were performed on each ear. Magnetic resonance imaging was used to determine the area of the cochlear modiolus and the volume of the endolymphatic duct and sac. RESULTS: The audiometric configurations for most patients sloped downward from the low to the high frequencies. A significant air-bone gap was computed at each of these test frequencies. Multifrequency tympanometry yielded resonance frequencies for the patients with EVA that was significantly lower than those measured for the control subjects. In general, for patients with EVA, the resonance frequency of the middle ear system decreased as the volume of the endolymphatic duct and sac increased. This inverse relation was significant (correlation coefficient = -0.483, P =.0157). However, there was no correlation between resonance frequency and the degree of cochlea modiolar deficiency. CONCLUSIONS: Clinically, our findings suggest that EVA probably should be included in the differential diagnosis for a patient who presents with a moderate to severe mixed hearing loss, a normal tympanogram at 226 Hz, and a resonance frequency that is abnormally low.     

Predictability of real ear hearing aid performance from coupler measurements

Results comparing hearing aid performance utilizing probe microphones with performance measured in a commercial hearing aid test box using an HA-2 coupler are presented. Sixteen hearing-impaired subjects (23 ears) were divided into two groups. Group I utilized unvented earmolds with short canals and large bores; group II utilized unvented earmolds with long canals and small bores. Results revealed that large individual differences across frequencies as well as within and between groups preclude predicting how a hearing aid will perform on a real ear from test box measurements.