Relative humidity of the external auditory canal in normal and abnormal ears,and its pathogenic effect

Objective: To find the relative humidity of the normal external ear canal and to demonstrate that the relative humidity of the external auditory canal was higher in abnormal ears, i.e. ears commonly associated with chronic discharge. Setting: Secondary health care within the ENT departments of Addenbrooke's and Hinchingbrooke hospitals. Design: A clinical observational study. Participants: Volunteers seen in ENT outpatients. Inclusion criteria for the normal ear group, was a normal ear with no history of infection or previous ear disease. Inclusion criteria for abnormal ear group commonly associated with chronic discharge. Exclusion criteria were the presence of pus or infection within the ear canal. Method: The relative humidity of the external ear canal was measured in normal and abnormal ears. Abnormal ears were grouped as those commonly associated with chronic discharge, mastoid cavities, tympanic perforations, recurrent otitis externa and hearing‐aided ears. Results: The range of relative humidity of normal ears is 40–70%. The humidity in abnormal ears was found to be significantly higher than the humidity in normal ears (P < 0.0001). Conclusion: The raised relative humidity in the external canal may explain the predisposition of certain abnormal ears to chronic discharge and infection. If the humidity of the canal could be brought down to a normal level, this could offer a new therapeutic treatment.     

Multifrequency tympanometry in normal ears

Susceptance and conductance tympanograms were recorded from 10 normal subjects with probe frequencies ranging from 220 to 910 Hz. Tympanometric shapes progressed through an orderly sequence of patterns, becoming more complex with increasing probe frequency. When the direction of ear-canal air pressure change was from negative to positive values, more complicated tympanometric shapes occurred for all subjects, compared to the positive to negative direction. The results are discussed in relation to the Vanhuyse et al. [Scand. Audiol. 4:45-50, 1975] model of tympanometric shapes. In general, the model is a good first approximation to the distribution of tympanometric patterns from normal ears.     

Acoustic-immittance measures in normal ears

A data base of acoustic-immittance measures in normal adults is presented. The subject pool consisted of 127 adults with normal hearing and a negative otologic history. Norms are presented for hearing thresholds, ipsilateral and contralateral acoustic-reflex thresholds, tympanometry, static acoustic-admittance measures, and middle-ear (tympanogram peak) pressure.     

Cochlear microvasculature in normal and damaged ears

The minute vessels of the cochlea were examined post mortem in normal guinea pigs and in others exposed to intense noise or treated with the ototoxic drugs gentamicin and quinine. The benzidine stain was used to display the capillary networks, and osmic acid for surface preparations, “thick” sections, and ultrathin sections for electron microscopic examination. The capillaries of the spiral ligament, i.e., the so-called arteriovenous anastomoses, do not show the characteristics of the muscular shunts described by Chambers and Zweifach. They are divided into two groups, the adstrial capillaries closely applied to the basal surface of the stria vascularis, and the poststrial capillaries which supply the tissue of the spiral ligament. Continuing beneath the floor of the external sulcus they form an alternating pattern with the root cells, and are surrounded by a specialized pericapillary tissue which resembles that found around the capillaries of the spiral prominence. These tissues are readily destroyed by gentamicin and other ototoxic aminoglycosidic antibiotics. Vasoconstriction of the outer and inner spiral vessels in response to noise and quinine appears to involve both contraction of pericytes and swelling of the endothelial cells. After prolonged exposure to noise or treatment with gentamicin, degeneration of capillaries with formation of intervascular strands and avascular channels is found in the suprastrial network of the spiral ligament. Similar capillary changes are seen in presbycusis, and in the deaf Dalmatian dog.     

Distribution of ear drops in normal ears

Ear drops are prescribed widely with little thought for the distribution inside the ear canal. This study compares the distribution of water and oil based drops. The results indicate that, under the test conditions, the penetration of ear drops is extremely variable. Water provided the greatest overall coverage, while the most viscous drops fared worst. It is suggested that in diseased ears even poorer penetration may result, which may explain the lack of response in some circumstances.     

Multifrequency multicomponent tympanometry in normal and otosclerotic ears

A multifrequency multicomponent admittance meter was used to evaluate 70 ears of patients affected by fenestral otosclerosis (Os ears), monolateral (16 cases) or bilateral (27 cases). The 16 contralateral ears of the patients with monolateral otosclerosis who presented a pure-tone air-bone gap less than 10 dB were evaluated separately (Cos ears). A group of 48 ears belonging to 24 otologically normal subjects (N ears), with hearing thresholds better than or equal to 10dB HL in the frequencies between 250 and 8000 Hz served as a control group. The purpose of the study was to evaluate the acoustic admittance characteristics of the three groups of ears, with particular regard to the parameters represented by the resonance frequency (RF), the acoustic conductance value (G) at RF and the individual interaural differences in these two parameters in the N and Cos groups. The degree to which fenestral otosclerosis can influence variations of RF and the correlation between the value of RF and conductive hearing loss in patients with clinically confirmed pictures and in the controlateral ears in the cases where the disease was clinically unilateral were also investigated. The study reveals statistically significant differences between the RF means in the N group (1085 +/- 244Hz) vs the Os group (1264 +/- 320 Hz) (p < 0.001) and between the G means in the N group (5.33 +/- 1.72 mmhos) vs the Os group (4.46 +/- 2.54 mmhos) (p = 0.04) and N group vs Cos group (3.42 +/- 2.27 mmhos) (p < 0.001). No correlation was found between the value of RF and conductive hearing loss. This study also shows how prognostic value may also be attributed to conductance at middle-ear pressure balancement: extremely low values for this parameter at RF are indicative of initial otosclerotic involvement of the oval window.     

Phasor diagram: a comparative study between normal ears and otosclerotic ears

The authors report their results from phase angle measurements by admittancemeter obtained by means of the phasor diagram, and conductance and susceptance tympanograms. The study was carried out on normal ears and otosclerotic ears. The authors noted a wide range of phase angle values and an absence of significant difference between the two populations studied.     

5000正常耳的纯音听阈观察

近年来观察了１２年间门诊就诊的５０００正常耳的纯音听力图。其结果显示正常耳的纯音听阈与标准听力零级相比，各频率均有不同程度的提高，表明正常人纯音听阈的提高可能是社会群体与生活在城市、社区、交通噪声、厂矿及音乐等噪声环境有关，而导致正常纯音听阈的提高。     

Stapedial reflexes in normal versus recruiting ears

The latency and magnitude of the stapedial reflex was examined in a group of normal-hearing Ss (N: 15) and in 15 Ss with unilateral sensorineural impairment exhibiting abnormal loudness growth in the impaired ear. Reflexes were determined at successive 2-db steps from threshold to 16 db above using a 2-kc/s stimulus tone. Latency and magnitude measurements were not statistically different between groups nor between ears within the pathological group. These results substantiate dependence of the stapedial reflex on loudness. Furthermore, there appears to be a dependence of the reflex magnitude on age, in that the magnitude tends to be less in older Ss.     

正常人中枢掩蔽测试结果分析

目的 :通过对一组耳科正常青年人进行中枢掩蔽测试 ,探讨其发生机制及其对听力学检查所产生的影响。方法 :分别测试有无对侧掩蔽声 (CAS)时的纯音气导听阈 ,比较其在相同频率不同强度的CAS时听阈的变化 ,即中枢掩蔽效应 (CME)的大小 ;同时测试相同强度不同频率CAS时CME的大小。结果 :CME具有频率特异性及强度特异性 ,中频 1kHz、2kHz时 ,其CME较低频及高频大 ,其中以频率为 2kHz时最明显 ;CAS强度在6 0dBHL以下时 ,CME随强度增加而增大 ,在 6 0dBHL时 ,2kHz处CME达 (11.5 3± 4 .38)dB ,CAS >70dBHL时 ,则出现过度掩蔽。结论 :因CME的存在 ,纯音听阈测试中 ,如所用CAS >4 0dBHL时 ,则需对测试结果进行修正 ;当CAS强度为 6 0dBHL时 ,CAS在 2kHz处产生大于 10dB的CME ,可用于对伪聋的鉴别     

Distortion product otoacoustic emissions in normal and hearing-impaired ears

Otoacoustic emissions of distortion products (DPOAE's) were recorded in normal and hearing-impaired human ears using relatively straightforward methods. Two pure-tone stimuli at fixed frequency levels of 73 dB HL for f1 and of 67 dB HL for f2 were used. The frequencies of the two primaries were chosen so that their geometric mean represented standard audiometric frequencies. Measurements of the emission amplitudes at 2f1-f2 and the adjacent noise floor were achieved by spectral averaging. A total of 101 subjects (199 ears) were tested. Seventy-seven ears in 46 subjects had normal hearing (hearing levels less than or equal to 20 dB at standard audiometric frequencies; average hearing levels, less than or equal to 10 dB). Thirty-six ears in 25 subjects had near-normal hearing (no hearing complaints, hearing levels less than or equal to 40 dB; average hearing levels, less than or equal to 20 dB). No significant differences in mean DPOAE values were apparent between these two groups of ears. All but two of these 113 ears (98%) showed emissions at three or more of the six frequencies tested between 1 and 6 kHz. Emissions were detected in more than 75% at each frequency between 1 and 6 kHz and in more than 85% between 1 and 4 kHz. A further 86 ears in 44 subjects exhibited varying degrees of sensorineural hearing loss caused by different pathologies. In general, emission amplitudes approximated the shapes of the audiograms, and a highly significant correlation between hearing thresholds and emission amplitudes was demonstrated in the frequency range of 1 to 4 kHz.(ABSTRACT TRUNCATED AT 250 WORDS)