A comparison of inter-aural attenuation with the Etymotic ER-3A insert earphone and the Telephonics TDH-39 supra-aural earphone.

One of the many reported advantages of the insert earphone over the supra-aural earphone is increased inter-aural attenuation (IA). Minimum values of IA determine the need for masking of the non-test ear in air-conduction audiometry. The aim of the present study was to measure inter-aural attenuation for the Etymotic Research ER-3A insert earphone (with deep and shallow insertion of the ear plug within the ear canal) and compare this with the supra-aural Telephonics TDH-39/MX41-AR earphone/cushion combination. Subjects were 18 adults ranging in age from 38 to 68 years (mean 50 years). Each subject had no hearing in one ear following translabyrinthine surgery for removal of an acoustic neuroma. The opposite ear had hearing thresholds better than 40 dB HL and an air-bone gap of less than 10 dB at any audiometric frequency. Pure tone air-conduction thresholds were obtained in the range 0.25-8 kHz. Deep insertion of the insert earphone was deemed to occur when the outside edge of the ear plug was flush with the entrance of the ear canal. Shallow insertion was deemed to occur when half of the ear plug (6 mm) was inside the entrance of the ear canal. IA was defined operationally as the difference between the good-ear and poor-ear not-masked air conduction threshold for a given audiometric frequency and earphone. The results show that the TDH-39/MX41-AR combination provides a median IA of approximately 60 dB with a lower limit of approximately 45 dB. Greater IA was obtained with the ER-3A insert earphone but this depended on the depth of insertion. With a deep insertion, the 1A values were some 15-20 dB greater than with the supra-aural earphone. Although frequency-specific IA values are provided, a simple rule of thumb is to apply masking to the non-test ear when the pure tone airconduction signal from the ER-3A insert earphone exceeds the bone conduction threshold of the non-test ear by 55 dB HL or more. If it is not possible to obtain a deep insertion depth this value should be reduced by 5 dB.     

Bone-conduction propagation in the human body: implications for high-frequency therapy

We assessed ultrasonic transmission in a dry skull; in a dry skull with water, simulating the living condition; in a cadaver head; and in six human subjects, one of whom exhibited no measurable hearing. By using these preparations, we concluded that fluid conduction is essential in the propagation of sound across the head, whereas the bone pathway is far less effective in that regard. Thus, there is little ear isolation beyond 10 dB even up to 80 kHz, extending the masking dilemma in cases of unilateral hearing loss.     

Effects of Contralateral Masking on High-Frequency Bone-Conduction Thresholds

The present study reports effects of contralateral masking on high-frequency threshold force levels in 28 normal-hearing subjects. High-frequency air- and bone-conduction thresholds were measured with a high-frequency auditory evaluation system using matched Koss HV/1A earphones and the Pracitronic KH 70/5 bone vibrator. Measurements were made for both unmasked and masked bone-conduction thresholds at the ipsilateral mastoid of the better ear. The contralateral masked condition was performed using 30-dB-SL 400-Hz narrow-band masking noise centered at frequency of test tone. The results demonstrated that masked high-frequency bone-conduction thresholds were 1.5 to 3.4 dB poorer than the unmasked thresholds and that these differences were statistically significant at 0.01 level of confidence except at 12 kHz. ANSI and ISO standards for bone-conduction threshold force levels for frequencies below 8.0 kHz have been established with contralateral masking stimuli. This study supports the need to use effective contralateral masking to eliminate cross hearing in investigations of high-frequency bone-conduction threshold measurements.     

Effects of contralateral masking on high-frequency bone-conduction thresholds

The present study reports effects of contralateral masking on high-frequency threshold force levels in 28 normal-hearing subjects. High-frequency air- and bone-conduction thresholds were measured with a high-frequency auditory evaluation system using matched Koss HV/1A earphones and the Pracitronic KH 70/5 bone vibrator. Measurements were made for both unmasked and masked bone-conduction thresholds at the ipsilateral mastoid of the better ear. The contralateral masked condition was performed using 30-dB-SL 400-Hz narrow-band masking noise centered at frequency of test tone. The results demonstrated that masked high-frequency bone-conduction thresholds were 1.5 to 3.4 dB poorer than the unmasked thresholds and that these differences were statistically significant at 0.01 level of confidence except at 12 kHz. ANSI and ISO standards for bone-conduction threshold force levels for frequencies below 8.0 kHz have been established with contralateral masking stimuli. This study supports the need to use effective contralateral masking to eliminate cross hearing in investigations of high-frequency bone-conduction threshold measurements.     

慢性化脓性中耳炎鼓室成形术前后骨导听阈变化的临床观察

目的:探讨慢性化脓性中耳炎术前骨导听阈提高与术后骨导听阈变化的相关因素.方法:单侧慢性化脓性中耳炎行鼓室成形术45例,术前3 d内和术后3个月分别行常规纯音测听,术前患侧与健侧相比,骨导听阈0.25～8.00 kHz至少连续2个或2个以上频率增加≥10 dB为术前骨导听阈提高阳性;术后3个月与术前相比,0.25～8.00 kHz至少2个或2个以上频率减少≥10 dB为术后骨导听阈下降阳性,增加≥10 dB为术后骨导听阈提高阳性.结果:45例中35例(77.8%)术前骨导听阈提高阳性,与病程长短、是否伴有胆脂瘤无关,但与听骨链破坏有相关性(P＜0.05),听骨链中断易导致术前骨导听阈提高;术前骨导听阈提高阳性35例中有6例(17.1%)术后骨导听阈下降阳性;45例患者中有5例(11.1%)术后骨导听阈提高阳性.结论:慢性化脓性中耳炎可造成骨导听阈提高,鼓室成形术不仅可使气导听阈下降、缩小气骨导差,还可使骨导听阈下降;术中过多触动听骨链及噪声等可造成术后骨导听阈提高.     

Predisposing factors for inner ear hearing loss association with chronic otitis media

The aim of the present study was to investigate the consequences of chronic otitis media on inner ear function. Retrospective analysis of conventional pure-tone audiometry tests was carried out on 344 patients who were scheduled for surgical treatment of unilateral chronic otitis media without other risk factors for sensorineural hearing loss. Bone conduction thresholds of diseased ears were compared with those of contralateral, non-diseased ears. Selected clinical features were assessed among diseased ears to examine possible influences on inner ear function. Mean bone conduction threshold differences varied from 0.6 dB at 0.5 kHz to 3.7 dB at 4 kHz. These differences augmented with increasing duration of middle ear disease. Impaired hearing by bone conduction thresholds of diseased ears correlated with increased age at every frequency and with an interruption of the ossicular chain only at higher frequencies. The severity of sensorineural hearing loss correlated with longer duration of middle ear disease. Thus, surgical treatment of dry and apparently stable tympanic membrane perforation is warranted.     

Predisposing factors for inner ear hearing loss association with chronic otitis media

The aim of the present study was to investigate the consequences of chronic otitis media on inner ear function. Retrospective analysis of conventional pure-tone audiometry tests was carried out on 344 patients who were scheduled for surgical treatment of unilateral chronic otitis media without other risk factors for sensorineural hearing loss. Bone conduction thresholds of diseased ears were compared with those of contralateral, non-diseased ears. Selected clinical features were assessed among diseased ears to examine possible influences on inner ear function. Mean bone conduction threshold differences varied from 0.6?dB at 0.5?kHz to 3.7?dB at 4?kHz. These differences augmented with increasing duration of middle ear disease. Impaired hearing by bone conduction thresholds of diseased ears correlated with increased age at every frequency and with an interruption of the ossicular chain only at higher frequencies. The severity of sensorineural hearing loss correlated with longer duration of middle ear disease. Thus, surgical treatment of dry and apparently stable tympanic membrane perforation is warranted.     

Masked threshold changes associated with angular separation of noise and signal sources

Threshold changes associated with separating a signal source and a masking white noise source from 0 degree to 90 degrees were determined for 0.5, 1 and 8 kHz pure tones and click trains. No changes occurred for the 0.5 and 1 kHz pure tones. Masked thresholds of 8 kHz pure tones and click trains decreased linearly by 9 and 13 dB respectively as angular separation was moved from 0 degree to 90 degrees. Changes in click train stimuli masked thresholds did not change significantly when the ear directed toward the masking source was occluded (11 dB drop at 90 degrees). The absence of changes at low frequencies and the similarity in magnitude of the changes in signals containing high frequency components with the responses to the monaural click trains, suggests that the threshold changes can be attributed to a head shadow effect. The casting of a sound shadow effectively lowers the noise level on the shielded side. These findings question the importance of cross-correlation techniques when detecting signals in noise.     

Pure-tone hearing thresholds in otologically healthy 5-year-old children in Finland

Summary We measured the pure-tone air and bone conduction hearing of 359 randomly selected otologically normal urban preschool children in Finland at the average age of 5.2 years. Children with otoscopically verified middle ear pathology or abnormal impedance audiometry were not included in this sample. The mean air conduction thresholds varied from 16.6 dB at 0.125 kHz to 6.6 dB at 2 kHz, and the mean bone conduction thresholds from 6.0 dB at 0.25 kHz to 0.7 dB at 4 kHz. The pure-tone average (of air conduction thresholds at 0.5, 1 and 2 kHz) of all the ears was 7.6 dB. The distribution of single air conduction hearing thresholds at the frequencies from 0.25 kHz to 4 kHz showed that 66%–75% were at the 5–10 dB level.     

Pure-tone hearing thresholds in otologically healthy 5-year-old children in Finland

We measured the pure-tone air and bone conduction hearing of 359 randomly selected otologically normal urban preschool children in Finland at the average age of 5.2 years. Children with otoscopically verified middle ear pathology or abnormal impedance audiometry were not included in this sample. The mean air conduction thresholds varied from 16.6 dB at 0.125 kHz to 6.6 dB at 2 kHz, and the mean bone conduction thresholds from 6.0 dB at 0.25 kHz to 0.7 dB at 4 kHz. The pure-tone average (of air conduction thresholds at 0.5, 1 and 2 kHz) of all the ears was 7.6 dB. The distribution of single air conduction hearing thresholds at the frequencies from 0.25 kHz to 4 kHz showed that 66%-75% were at the 5-10 dB level.     

The pure-tone hearing thresholds of otologically healthy 14-year-old children

The mean pure-tone air conduction (AC) and bone conduction (BC) hearing thresholds (HT) of 534 randomly selected, caucasian, white, urban children with normal otoscopy, otomicroscopy and impedance audiometry, i.e. normal middle ear function, are presented here. Children with pathological middle ear findings or abnormal impedance audiometry were excluded. The average age was 13.8 years, SD 0.5, at the date of examination. The mean air conduction thresholds varied between 0.6 dB at 1 kHz and 9.9 dB at 6 kHz, and the bone conduction thresholds varied between -1.1 dB at 0.5 kHz and 1.1 dB at 4 kHz. The pure-tone average (PTA) (the average of AC hearing thresholds of 0.5, 1 and 2 kHz) of all ears was 1.5 dB. Ninety to ninety-eight per cent of pure-tone AC hearing thresholds at frequencies of 0.5-4 kHz were between -5 dB and 10 dB. The distributions are presented and compared.     

Incidence of hearing decline in the elderly

Pure-tone audiometry was done on 1475 persons on two occasions 6 years apart by the same audiologist in the same facility. The age of the subjects ranged from 58 to 88 years at the initial testing and 63 to 95 at the second. The average 6-year threshold change ranged from 1 to 8 dB at 250-6 kHz and 10-15 dB at 8 kHz. The differences in thresholds fell into two patterns, one for low frequencies (250-1 kHz) and the other for high frequencies (4-8 kHz). For the lows, thresholds worsened at an increasing rate with increasing age independent of the initial hearing level, and women's thresholds worsened more than men's. For the highs, the rate of threshold change decreased with age and with the initial threshold at rates that did not differ between genders. Using a change in PTA (0.5, 1, 2 kHz) of greater than 10 dB as a criterion, significant worsening occurred in the right ear in 8.5%, in the left ear in 13.5%, and in both ears of 4.1% of the subjects over the 6 year period. The rate of significant worsening increased with age. Although hearing loss increased with age, age alone accounted for less than 10% of the variance. Therefore, factors that co-vary with age may be responsible. The difference in phenomena between the low frequencies and the highs suggests that two different processes are occurring. Hair-cell degeneration is the most likely cause for the change in the high frequencies. Strial atrophy or other intracochlear processes may be the cause of the low frequency changes.     

慢性化脓性中耳炎与感音神经性聋的相关性分析

目的：探讨慢性化脓性中耳炎与感音神经性聋之间的相关性。方法：回顾分析174例单侧慢性化脓性中耳炎患者的骨导阈值改变。采用配对t检验分析0．5kHz，1．0kHz，2．0kHz，4．0kHz患耳与健耳骨导阈值的差异，单因素方差分析法分析胆脂瘤存在及听骨链破坏对语频(0．5kHz，1．0kHz，2．0kHz)和4．0kHz骨导阈值的影响，直线回归法讨论了语频和4．0kHz骨导阈值改变与年龄和病程之间的相关性。结果：患耳与健耳各频率骨导阈值之间差异有统计学意义。语频骨导听力损失程度随着患者年龄的增加而逐渐加重。胆脂瘤的存在以及听骨链破坏亦未增加感音神经性聋的发生概率。结论：慢性化脓性中耳炎可引起感音神经性聋。高频骨导听阈较低频更易受到影响。     

Otoacoustic emission, evoked potential, and behavioral auditory thresholds in the rhesus monkey (Macaca mulatta).

Distortion product otoacoustic emission (DPOAE), auditory brainstem evoked response (ABR), and behavioral thresholds were recorded in a group of 15 adult rhesus monkeys with normal auditory function. DPOAE thresholds were recorded with stimulus parameters selected to maximize signal-to-noise ratio. Additional averaging at the lowest frequencies ensured comparable noise levels across frequencies. DPOAE thresholds decreased with increasing frequency (f(2)=0.5-16 kHz) and at 16 kHz were close to 0 dB SPL. ABR thresholds were best from 1 through 16 kHz (32-38 dB peSPL); higher at 0.5 (45 dB peSPL), 24 (39 dB peSPL), and 30 kHz (49 dB peSPL). At all levels including threshold, the early ABR waves (II and I) were more prominent at the high frequencies while the later waves (IV and V) were more prominent at the low frequencies. The behavioral thresholds recorded were similar to those reported by other researchers although elevated by about 10 dB presumably because of the complexity of the threshold task. DPOAE and ABR thresholds can be reliably and efficiently recorded in the rhesus monkey and provide information concerning site of processing in the auditory pathway not directly available from behavioral data.     

Extra-high-frequency noise remotely masks and alters temporal integration at lower frequencies

A quasi-free-field technique was used to assess the effects of extra-high-frequency-band masking on detection threshold of middle and high (1-7 kHz) frequencies. At an SPL of 60 dB, the 10- to 20-kHz masker produced a slight amount of masking. Increasing the masking level by another 5 dB produced a disproportionate increase of the detection thresholds. This increase was greatest in response to 4- and 5-kHz stimuli, and was detected with both constant and pulsed tones. Decreasing the bandwidth of the masker reduced the magnitude of the effect, but not the frequency-specific pattern of the remote masking. Extra-high-frequency masking also increased the amount of temporal integration at middle and high frequencies. The data are discussed in reference to peripheral and central neural changes associated with sensorineural hearing loss.     

Paediatric small cavity mastoid surgery: second look tympanotomy

OBJECTIVE: Following surgery for retraction pocket/cholesteatoma there is risk of residual disease, after canal wall up surgery a second look tympanotomy is routinely recommended. After canal wall down (CWDM) surgery this is not routine. In certain situations the senior author recommends second look tympanotomy. This report examines the outcome of this management paradigm applied to small cavity mastoid surgery for children. METHOD: A retrospective review of small cavity mastoid surgery for children with cholesteatoma or discharging retraction pocket disease. The primary procedure and surgical findings at second look tympanotomy are reported as well as the pre- and 1 year post-operative air and bone conduction thresholds and air-bone gap averaged across frequencies 0.5, 1, 2 and 4kHz and the mean pre- and post-operative bone conduction threshold at 4kHz. A Student t-test was used to compare hearing results. RESULTS: Forty five were children reviewed at 1 year. Twelve (27%) were recommended second look tympanotomy, of which 10 had surgery; all were free of residual disease. At second look two children had ossiculoplasty performed, four had adhesions divided. Six children had formed a myringostapediopexy after their first surgery. The mean pre-op bone conduction threshold was 6.3dB for those having single stage surgery and 5.6dB for those having a second look and the post-operative thresholds were 7.8 and 10.2dB, respectively. The mean preoperative air conduction threshold was 32.6dB for single stage surgery and 31.1dB for staged surgery and at 1 year 29.2 and 40.8dB. This was a significant difference. After second look, the air conduction threshold was 34.5dB, and not significantly different from those who had single stage surgery. The mean pre-treatment 4kHz bone conduction threshold was 6.3 and 5.6dB for single stage surgery and second look tympanotomy and after surgery, respectively, 9.8 and 14.5dB. These changes are not statistically significant. CONCLUSION: The small cavity mastoidectomy approach allows meticulous removal of disease from the middle ear and for certain indications second look tympanotomy is recommended. Planned second look tympanotomy has demonstrated excellent early disease control as well as allowing timely management of any pathology affecting the middle ear sound transformation mechanism.     

Longitudinal study of pure-tone thresholds in older persons

OBJECTIVE: Pure-tone thresholds for conventional and extended high frequencies were analyzed for 188 older adult human subjects (91 females, 97 males). The objectives were to study longitudinal changes in thresholds as well as the effects of initial threshold levels, age, gender, and noise history on these longitudinal changes. DESIGN: At the time of entry into the study, subjects' ages ranged from 60 to 81 years, with a mean age of 68 years. Subjects had between 2 and 21 visits (mean = 9.81 visits) over a period of 3 to 11.5 years (mean = 6.40 years). Conventional pure-tone thresholds at 0.25 to 8 kHz were measured during most visits. Extended high-frequency (EHF) thresholds at 9 to 18 kHz were measured every 2 to 3 years. The slope of a linear regression was used to estimate the rate of change in pure-tone thresholds at 0.25 to 18 kHz for each ear. A questionnaire was used to identify those subjects with a positive noise history. RESULTS: The average rate of change in thresholds was 0.7 dB per year at 0.25 kHz, increasing gradually to 1.2 dB per year at 8 kHz and 1.23 dB per year at 12 kHz. The rate of change for thresholds increased significantly with age, at 0.25 to 3, 10, and 11 kHz for females and at 6 kHz for males. After adjusting for age, females had a significantly slower rate of change at 1 kHz but a significantly faster rate of change at 6 to 12 kHz than males. For 0.25 and 1 kHz, subjects with more hearing loss at higher frequencies had a faster rate of change at these frequencies, whereas for 6 and 8 kHz, subjects with more hearing loss at mid and high frequencies had a slower rate of change at these frequencies. The rates of threshold change for subjects with a positive noise history were not statistically different from those with a negative noise history. CONCLUSIONS: On average, hearing threshold increased approximately 1 dB per year for subjects age 60 and over. Age, gender, and initial threshold levels can affect the rate of change in thresholds. Older female subjects (> or =70 years) had faster rate of change at 0.25 to 3, 10, and 11 kHz than younger female subjects (60 to 69 years). Older male subjects had faster rate of change at 6 kHz than younger male subjects. Females had a slower rate of change at 1 kHz and a faster rate of change at 6 to 12 kHz than males. Subjects with higher initial thresholds at low and mid frequencies tended to have faster rate of threshold change at 0.25 to 2 kHz in the following years. Subjects with higher initial thresholds at mid and higher frequencies tended to have slower rate of change at 6 to 8 kHz in the following years. Noise history did not have a significant effect on the rate of threshold changes.     

Application of phase-induced lateralization to the Stenger test.

The Stenger test was employed to estimate the genuine hearing thresholds in normally hearing volunteer subjects simulating a total unilateral loss. The test was carried out in its standard form and in a modified form in which a phase shift was introduced between the signal delivered to the two ears, set to produce phase-induced lateralization towards the 'poor' ear. The standard test estimated the thresholds at a mean of 13.5 dB above the true thresholds at five frequencies from 250 Hz to 4 kHz. Thresholds at the different frequencies were compared, and although thresholds were lower for the higher frequencies, the apparent effect of frequency was not statistically significant. The modified test, using a 90 degrees phase shift, was found to enhance the test at 250 and 500 Hz (thresholds estimated at about 7 dB above true values), but not significantly at 1 kHz.     

The Preyer reflex--an easy estimate of hearing function in guinea pigs

Preyer reflex thresholds elicited monaurally by tone bursts from 0.25 to 8 kHz were determined in more than 150 guinea pig ears. Normal reflex thresholds were between 85 and 95 dB SPL in the low and middle frequencies, decreasing to 75 dB in the higher frequencies. The range of measurements at single frequencies usually did not exceed 10 dB. In unselected populations of adult guinea pigs, about half of the animals had increased reflex thresholds--at least unilaterally, in most cases due to middle ear infections. The Preyer reflex showed parallel threshold increase with compound action potential thresholds in conductive loss and recruitment in cochlear hearing loss. Normal Preyer reflex thresholds do not necessarily mean normal hearing, but increased thresholds do indicate hearing impairment. This technique is valuable in the selection and monitoring of animals for otologic experiments.     

慢性化脓性中耳炎对老年患者骨导听阈的影响

目的 探讨慢性化脓性中耳炎对老年患者骨导听阈的影响.方法 回顾性分析2005年1月至2009年3月在北京同仁医院耳鼻咽喉头颈外科住院治疗且资料完整的60岁以上单侧慢性化脓性中耳炎患者76例,分别记录患侧耳与对侧耳0.5、1、2、4 kHz四个频率的骨导阈值,以及每例患者中耳炎发病持续时间、听骨链是否中断、是否存在胆脂瘤等情况,并对记录的数据进行统计学分析.结果 患耳0.5、1、2、4 kHz四个频率的骨导阈值均高于对侧耳,差异有统计学意义(P值均＜0.01);胆脂瘤组与非胆脂瘤组相比,仅2 kHz双耳骨导阈值差的差异具有统计学意义(Z=-1.975,P=0.048);听骨链中断组与非中断组双耳骨导阙值差的差异也仅在2 kHz具有统计学意义(Z=-2.721,P=0.007);中耳炎病程10年以下组与10年以上组在1 kHz和2 kHz这两个频率的双耳骨导阈值差的差异具有统计学意义(Z值分别为-2.877和-2.624,P值均＜0.01).结论 慢性化脓性中耳炎可以使老年患者骨导阈值提高,对于老年慢性化脓性中耳炎仍应尽早积极治疗,避免感音神经性听力损失.