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PubMed2002

Detection of Alloiococcus otitidis in the nasopharynx and in the outer ear canal.

Alloiococcus otitidis has been recovered from the middle ear of children with otitis media with effusion, but its natural habitat is not known. To determine whether the nasopharynx and the outer ear canals are the natural habitats of A. otitidis, 145 swabs (50, nasopharynx; 95 outer ear canal) collected from 50 children were screened by polymerase chain reaction. A. otitidis DNA was detected in seven (4.8%) of the 145 specimens, of which four were nasopharynx, and three outer ear canal. These results indicate that the nasopharynx and outer ear canal may be the body sites for localization of A. otitidis.

Child↗
PubMed1982

Management of ear-canal collapse.

Thresholds were measured at 250, 500, 1,000, 2,000, 3,000, 4,000, 6,000, and 8,000 Hz in 20 normal adult ears and in ten ears from adults with varying amounts of ear-canal collapse. To alleviate the attenuation caused by ear-canal collapse, ear-canal inserts, postauricular pads, or circumaural cushions (Telephonics 510-020) were used with earphones (TDH-49). The circumaural cushions provided the lowest thresholds for the listeners with ear-canal collapse. Although thresholds with the ear-canal inserts were comparable to those with the circumaural cushions for many of the listeners, the ear-canal inserts were not suitable for listeners with more severe ear-canal collapse because the insert was displaced when the supra-aural cushion was placed on the pinna. Thresholds with the postauricular pinna pads were higher than with the circumaural cushions for most individuals.

Adult↗
PubMedDate not supplied

Infrared tympanic temperature and ear canal morphology.

Several publications indicate that the infrared tympanic temperature (IRTT) underestimates the core temperature of the body when the ear canal is long, curvy and narrow. In order to quantify these observations, a study was performed in 10 subjects. The IRTT was determined and compared to the oesophageal temperature (Tes), taken as the reference for core temperature. Also, the oral and rectal temperatures were monitored. A three-dimensional print of the ear canal was made to determine the ear canal morphology. The core temperature of the subjects was increased by at least 1 degrees C during the experiment in order to investigate the dynamics of the core temperature assessment. Two devices were used to determine the IRTT: the Braun Thermoscan PRO 1 and the predecessor of the Braun IRT3020 (code name IRT3000P). Both IRTT-devices underestimated the core temperature, as measured by Tes, by 0.38 degrees C on average. The difference DeltaT between IRTT and Tes was related to ear canal morphology. The circumference of the ear canal at the distal bend in the ear canal and the visibility of the tympanum were the most important parameters. About 22% of the variance in DeltaT was explained by ear canal morphology for the steady state resting period. Wide ear canals and good visibility of the tympanic membrane were related to a smaller DeltaT. A good visibility of the tympanic membrane was generally found in the absence of cerumen. The IRT3000P showed better results than the PRO 1 (DeltaT: -0.31 +/- 0.27 degrees C and -0.44 +/- 0.30 degrees C respectively). Also, the IRT3000P was less dependent on ear canal morphology. The dynamic response of the measured core temperatures was determined by the decrease or rise in core temperature after the heating period was ended. The oesophageal temperature dropped by 0.22 degrees C. The IRTT and oral temperature showed an identical increase of 0.19 degrees C. The slow reacting rectal temperature had an after rise of 0.49 degrees C.

Adult↗
PubMed1985

The spatial distribution of sound pressure within scaled replicas of the human ear canal.

A theoretical model for calculating the variation of sound pressure within the ear canal is presented. The theory is an extension of the horn equation approach, and accounts for the variation of cross-sectional area and curvature of the ear canal along its length. Absorption of acoustic energy at the eardrum is included empirically through an effective eardrum impedance that acts at a single location in the canal. For comparison, measurements of the distribution of sound pressure have been made in two replica ear canals. Both replicas have geometries that duplicate, as nearly as possible, that of a real human ear canal, except that they have been scaled up in size to increase the precision of measurements. One of the replicas explicitly contains a load impedance to provide acoustical absorption at a single eardrum position. Agreement between theory and experiment was good. It is clear that at higher frequencies (above about 6 kHz in human ear canals), this theoretical approach is preferable to the more usual "uniform cylinder" approximation for the ear canal. At higher frequencies, there is no unique eardrum pressure; rather, very large variations of sound pressure are found over the tympanic membrane surface.

Acoustics↗
PubMed1987

Calibration of ear canals for audiometry at high frequencies.

A procedure is described for determining the absolute sound pressure at the inner end of the ear canal when a sound source is coupled to the ear, for frequencies in the range 8-20 kHz. The transducer that generates the sound is coupled to the ear canal through a lossy tube, yielding a source impedance that is approximately matched to the characteristic impedance of the ear canal. A small microphone is located in the coupling tube close to the entrance to the ear canal. Calibration is carried out by measuring the response at this microphone when an impulse is applied at the transducer. To estimate the sound pressure at the medial end of the ear canal, the Fourier transform of this impulse response is corrected by an all-pole function in which the poles are estimated from the minima in this Fourier transform. Data on individual ear canals are presented in terms of gain functions relating the sound pressure at the medial end of the ear canal to the sound pressure when the coupling tube is blocked. The average gain function for a group of adult ears increases from 2 to 12 dB over the frequency range 8-20 kHz, in rough agreement with data from ear-canal models. Possible sources of error in the calibration procedure are discussed.

Acoustics↗
PubMed1990

Morphologic measurements of the external horizontal ear canal of dogs.

Microscopic anatomy of the horizontal part of the external ear canal was evaluated in 24 dogs. Sixteen dogs were from breeds known to have a predisposition to otitis externa. The remaining 8 dogs were from breeds that do not have a predisposition to otitis externa. Dogs were separated into groups according to predisposition to otitis externa: group 1-predisposed dogs without otic inflammation, group 2-predisposed dogs with otic inflammation, and group 3-nonpredisposed dogs without otic inflammation. Qualitative microscopic evaluation of distribution of hair follicles revealed hair within proximal, middle, and distal regions of the horizontal ear canal in all breeds. The degree of keratinization was directly proportional to the presence of otic inflammation and was excessive in group-2 dogs. Quality of sebaceous glands within the horizontal ear canal was similar among dogs with and without otitis externa, whereas the quantity of apocrine tubular glands was significantly increased (P less than 0.05) in dogs with otitis. Quantity of apocrine tubular glands was also greater in group-1 dogs than in group-3 dogs. Thickness of the soft tissue in the external ear canal increased in direct proportion to the progression of disease and was greatest in the proximal region of the affected ear canal. Soft tissue located caudally between nonopposing ends of the annular cartilage, within the proximal region of the horizontal ear canal, contained few glands and hair follicles in dogs without otitis externa. In dogs with otitis externa, this region was infiltrated by distended apocrine tubular glands.

Age Factors↗
PubMed2002

Anteroposterior approach with split ear canal for cochlear implantation in severe malformations.

OBJECTIVE: To present an anteroposterior approach with split ear canal technique in severe malformed ears in which cochlear implantation is not possible through the standard facial recess approach. SETTING: The operation was performed at Hacettepe University Medical Faculty, which is a tertiary care center. STUDY DESIGN: Case report. PATIENT: A 4-year-old female patient with severe Mondini malformation whose facial nerve was completely dehiscent and overlying the stapes and round window. INTERVENTION: The anteroposterior approach was used, and the middle ear was entered after the tympanomeatal flap was elevated. The posterior wall of the ear canal was split longitudinally with a diamond drill. The electrode was inserted easily through the ear canal and then transferred into the mastoid. CONCLUSION: The anteroposterior approach with split ear canal method may be used if, during facial recess, the landmarks in the middle ear (stapes, stapedius tendon, round window, and promontory) cannot be identified clearly because of an abnormal facial nerve (coursing anteriorly, preventing the use of a drill). It is an alternative for the canal wall down procedure.

Abnormalities, Multiple↗
PubMedDate not supplied

Ultrasonographic evaluation of the external ear canal and tympanic membrane in dogs.

Ultrasonographic imaging of the canine external ear canal, tympanic membrane, and tympanic bulla was described in five healthy beagle dogs before and after infusion of saline into the ear canal. Saline served as an acoustic window. With this method, the external ear canal, and tympanic bulla were visible in the same imaging plane and the integrity of the tympanic membrane could be evaluated indirectly by confirming an intact tympanic membrane, which appeared at the end of the ear canal as a hyperechoic line with reverberation. Experimentally, perforated tympanic membrane could be evaluated by identifying anechoic saline in the tympanic bulla lumen. The air and fluid-filled tympanic bulla were also visualized. Ultrasonography with saline as an acoustic window appears to be helpful for the evaluation of the external ear canal, tympanic membrane, and tympanic bulla and it may have the potential to be a useful clinical tool in evaluation of integrity of the tympanic membrane.

Animals↗
PubMed2004

Otoscopic evaluation of the ear canal.

Otoscopic evaluation of the external ear canal and tympanic membrane is the first diagnostic procedure that should be performed in animals presented with otitis externa. It is important to become familiar with the normal structures of the ear to identify any abnormalities. The video otoscope greatly enhances visualization of these structures as well as aiding in retrieval of foreign bodies, biopsy of masses, and performance of a myringotomy. In some cases, a complete otoscopic examination is not possible on the first visit, and the animal may require anti-inflammatory medications or otic flushing to visualize the entire ear canal as well as the tympanic membrane. The purpose of the otoscopic examination is to address the otitis by evaluating the condition of the ear, looking for any masses or foreign bodies; noting the presence, consistency, and color of any exudate; and evaluating the patency of the tympanic membrane. Once a complete otic evaluation has been performed, additional diagnostics as well as a treatment plan can be formulated.

Animals↗
PubMed1990

Estimation of eardrum acoustic pressure and of ear canal length from remote points in the canal.

Sound pressure distributions in the human ear canal, whether unoccluded or occluded with ear molds, were studied using a probe tube technique. On average, for frequencies below 6 kHz, the measuring probe tube had to be placed within 8 mm of the vertical plane containing the top of the eardrum (TOD), determined optically, in order to obtain sound pressure magnitudes within 6 dB of "eardrum pressure." To obtain that accuracy in all of the eight subjects studied, the probe had to be within 6 mm of the TOD. Since probe location relative to the drum has to be known, a purely acoustic method was developed which can be conveniently used to localize the probe-tip position, utilizing the standing wave property of the sound pressure in the ear canal. The acoustically estimated "drum location" generally lay between the optically determined vertical planes containing the TOD and the umbo. On average, the "drum location" fell 1 mm medial to the TOD. Of the 32 estimates made acoustically in various occluded and unoccluded conditions in 14 subjects, 30 estimates lay within a +/- 2-mm range of this average.

Acoustic Stimulation↗
PubMed1993

Quantifying ear-canal geometry with multiple computer-assisted tomographic scans.

Several audiological tests require knowledge of the sound-pressure spectrum at the eardrum. However, microphone readings are typically made at another, more-accessible position in the auditory canal. Recordings are then "adjusted" to the plane of the eardrum via mathematical models of the ear canal and eardrum. As bandwidths of audiological instruments have increased, ear-canal models have, by necessity, become more precise geometrically. Reported herein is a noninvasive procedure for acquiring geometry of the ear canal in fine detail. The method employs a computer-assisted tomographic (CAT) scanner in two steps to make radiographic images of parasagittal cross sections at uniform intervals along the lateral length of the canal. Accuracy was evaluated by comparing areas of cross sections appearing in radiographic images of a cadaver ear canal to cross sectional areas of corresponding michrotome slices of an injection mold of the same canal. Percent differences between these two areas had a mean value of 9.65% for 26 different cross sections of the one ear canal studied. Ear canal volume estimated from the CAT images was 6.12% different from the estimated volume of the injection mold: an improvement over the reported 39% maximum error of conventional acoustic volume measurements.

Acoustic Stimulation↗
PubMed1994

Pressure transfer function and absorption cross section from the diffuse field to the human infant ear canal.

The diffuse-field pressure transfer function from a reverberant field to the ear canal of human infants, ages 1, 3, 6, 12, and 24 months, has been measured from 125-10700 Hz. The source was a loudspeaker using pink noise, and the diffuse-field pressure and the ear-canal pressure were simultaneously measured using a spatial averaging technique in a reverberant room. The results in most subjects show a two-peak structure in the 2-6-kHz range, corresponding to the ear-canal and concha resonances. The ear-canal resonance frequency decreases from 4.4 kHz at age 1 month to 2.9 kHz at age 24 months. The concha resonance frequency decreases from 5.5 kHz at age 1 month to 4.5 kHz at age 24 months. Below 2 kHz, the diffuse-field transfer function shows effects due to the torsos of the infant and parent, and varies with how the infant is held. Comparisons are reported of the diffuse-field absorption cross section for infants relative to adults. This quantity is a measure of power absorbed by the middle ear from a diffuse sound field, and large differences are observed in infants relative to adults. The radiation efficiencies of the infant and the adult ear are small at low frequencies, near unity at midfrequencies, and decrease at higher frequencies. The process of ear-canal development is not yet complete at age 24 months. The results have implications for experiments on hearing in infants.

Age Factors↗
PubMed1996

Effects of ear canal occlusion and masking on the perception of voice.

This study examined the effect of ear canal occlusion and masking noise on four parameters of voice: (1) average fundamental frequency, (2) intensity in decibel (dB), (3) maximum fundamental frequency observed in a given sample (max), and (4) minimum fundamental frequency observed in a given sample (min). 12 normal hearing undergraduates produced the vowel /i/ ten times under conditions of unoccluded ear canal, ear canal occluded with a sound attenuating earplug, or masking noise. Other than a small (.73 dB) decrease in intensity, analysis showed no significant changes under the occluded condition; however, the masking condition showed statistically significant increases in the fundamental frequency, the intensity, and the maximum and minimum frequency as well as an increased range of frequencies.

Adult↗
PubMed2007

Osteotome technique for removal of symptomatic ear canal exostoses.

OBJECTIVES/HYPOTHESIS: This study was undertaken to assess a transcanal osteotome technique for removing symptomatic ear canal exostoses. Outcome measures included healing rates and the rate of complications. STUDY DESIGN: Prospective study in a private practice. METHODS: A straight 1-mm osteotome and a curved 1-mm osteotome were used by way of a transcanal approach to incrementally remove obstructive ear canal exostoses. If anterior or superior bone growths were closely approximating the tympanic membrane, they were partially removed with a 1.5 mm cylindrical end- and side-cutting burr. Healing rates were monitored with weekly postoperative visits. RESULTS: Two hundred twenty-one ear canals (140 patients) were consecutively treated with this technique. Healing was achieved at 2 to 8 (average 3.50) weeks, with 90% healed by 4 weeks. There were 4 mobilizations of a full-thickness segment of anterior bony canal wall; 3 exposures of periosteum anterior to the anterior bony wall; 1 tear of the tympanic membrane requiring a tympanoplasty; 18 anterior and 11 posterior tympanic membrane tears that healed spontaneously; 3 instances of sensorineural hearing decrease; 3 cases of new-onset postoperative tinnitus; and 1 instance of postoperative positioning vertigo. There were no lacerations of the tympanic membrane by an osteotome, no facial nerve injuries, no soft tissue stenoses of an ear canal, and no skin grafting of an ear canal. CONCLUSIONS: The described technique of using osteotomes transcanal for removal of symptomatic obstructive ear canal exostoses promoted rapid healing and was effective and safe.

Adolescent↗
PubMed1988

Use of disposable ear canal electrodes in auditory brainstem response testing.

In this study a disposable ear canal electrode and stimulus delivery system (the Enhancer l) was evaluated for its clinical utility and the observed enhancement of the auditory brainstem response Wave I with its use. Data were collected from normally and abnormally hearing subjects, with both the conventional forehead-to-mastoid electrode array and the forehead-to-ear canal electrode arrangement provided by the Enhancer I ear canal electrode setup. For the normally hearing group, simultaneous acquisition of forehead-to-ipsilateral ear canal and forehead-to-ipsilateral mastoid electrode linkages was obtained. For the abnormally hearing subjects, a comparison was made between the Enhancer I system and the conventional forehead-to-mastoid electrode configuration used with a TDH-49 transducer for click delivery. Our findings indicate that Wave I was enhanced substantially when using the disposable ear canal electrode compared with the more conventional forehead-to-mastoid electrode configuration for both normally and abnormally hearing subjects. The Enhancer I electrode evaluated in this study proved to be painless for the subjects and extremely easy to use, requiring no more time in subject preparation than the more common surface recording electrode application.

Adult↗
PubMed1997

The effect of the evanescent wave upon acoustic measurements in the human ear canal.

When making acoustic measurements in a human ear canal, it is often necessary to monitor the output of a sound source with a microphone positioned within a few millimeters of that sound source. This microphone will not only measure the pressure due to the propagated acoustic wave, which we wish to measure, but also the pressure due to the evanescent wave. The pressure due to the evanescent wave can be viewed as a source of error in the measurement of the propagating acoustic wave. This paper attempts to quantify the magnitude of this error. Theoretical predictions are made of the relative level of the evanescent sound pressure in a number of source and microphone arrangements applicable to ear canal measurements. It is shown that these theoretical predictions represent an upper limit of evanescent sound pressure that can be measured experimentally. The maximum measurement error due to the presence of the evanescent wave in human ear canals below 10 kHz is predicted to be 3 dB in adults and 1.3 dB in 1 month old infants, when the loudspeaker and microphone ports are spaced more than 2 mm apart.

Acoustic Stimulation↗
PubMed1996

Easily applied ear canal electrodes improve the diagnostic potential of auditory brainstem response.

The diagnostic potential of easily applied ear canal electrodes was studied in patients with asymmetric auditory brainstem response (ABR). The study included 50 consecutive patients with unilateral auditory signs or symptoms who at conventional ABR testing manifested not only a delayed wave V in relation to the non-symptomatic ear, but also absence of wave I in the symptomatic ear. The patients were examined with ear canal electrodes at the same session as the conventional ABR testing. As application of the ear canal electrode is easy, painless and safe, the auditory assistant could use the ear canal electrode and obtain the recordings unaided and without having first to consult a physician. Estimated extra time for the canal electrode procedure was 15 min and no adverse effects were noted. With the use of an ear canal electrode a significant wave I could be identified in 72% (36.50) of cases. Thus, ability to observe the most peripheral component (wave I) of the ABR was facilitated by using an easily applied ear canal electrode. Hence, in these patients the diagnostic potential of ABR for acoustic tumors was increased owing to the availability of a direct measure of tumor effect on the auditory nerve, i.e., the neural transmission time.

Adolescent↗