Entrance Of Canal Research Articles

Development of monaural and binaural behind-the-ear cartilage conduction hearing aids

Hosoi (2004) found a pathway for clear sound transmission via aural cartilage. Our research group is developing a new hearing aid using this mechanism. The cartilage conduction hearing aid can be used in patients who cannot insert the earplugs of conventional hearing aids. The cartilage conduction hearing aid (model HD-GX) is composed of a main unit, a transducer, and a fitting part. The ring-shaped fitting part is placed in the entrance of the ear canal, and the vibration at the cartilage then generates sound in the external auditory canal. The cartilage conduction sound remains in the canal and reduces the risk of acoustical feedback. Considering this advantage, we designed it to wear behind the ear (BTE) (model HD-GX2). As binaural cartilage conduction can present sound directivity equivalent to that of air conduction, we then developed a binaural cartilage conduction hearing aid (model HD-GX3) by combining two BTE hearing aids.

Measuring pressure and particle velocity along the human ear canal

A non-invasive method of measuring or estimating accurately the head-related transfer functions (HRTFs) and headphone transfer functions (HpTFs), i.e., the pressure at the eardrum rather than at the blocked ear canal entrance is called for. In this work, a miniature-sized acoustic pressure–velocity sensor is used to measure both pressure and velocity along the ear canals of human test subjects. The measurements are used to study the applicability of a recently proposed method of estimating the pressure at the eardrum from pressure–velocity measurements made at the ear canal entrance. The measurement results are compared to results from computational modeling with human ear canal parameters. In addition, the effect of the PU-sensor itself on the pressure at the eardrum is studied. It is shown that the estimation method is reliable and accurate for most human subjects. The diameter and the shape of the ear canal affect the results in such a way that the best results are obtained with wide and straight ear canals whereas less accurate results are obtained with narrow and curved ear canals. It is concluded that the estimation method facilitates the obtaining of individual HRTFs and HpTFs at the eardrum using non-invasive measurements.

Individual in-situ calibration of insert headphones

An important procedure in binaural reproduction is the calibration of headphones, which is commonly achieved by first measuring the headphone transfer functions (HpTFs). The commonly used methods of measuring the HpTF are not applicable for insert headphones, since the inserts block the ear canal entrance and since the transducer ports of the inserts are inside the ear canals. Recently, an alternative technique of obtaining HpTFs of inserts using measurements with in-ear microphones, computational modeling, and electro-acoustic Norton-type source models of the inserts has been proposed. In this study, the technique is evaluated using measurements at the eardrums of eight human subjects and computational modeling with normal human ear canal parameters. In addition, different methods of obtaining the electro-acoustic source model parameters are compared. It is shown that the most reliable method of obtaining the Norton source parameters of insert headphones is through measurements with a miniature-sized particle velocity sensor and several tubes with different cross-sectional diameters as acoustic loads. The evaluations show that the proposed technique of obtaining the HpTFs of insert headphones is accurate and reliable at least up to 8 kHz, which bolsters the applicability of the technique for individual in-situ calibration in binaural reproduction.

Restoration of primary anterior teeth using intracanal polyethylene fibers and composite: an in vivo study.

To evaluate the clinical performance of polyethylene fiber for anterior primary teeth restorations in children after 2.5 years, according to modified Ryge criteria. Fifty-five maxillary incisors with extensive caries in 24 Iranian patients (mean age 4.2 years) were restored. All teeth were treated endodontically. First, 4-mm layer of paste at the entrance of canal was removed, and a thin base layer of polycarboxylate cement was placed at the bottom of the prepared canal. All tooth surfaces were etched, rinsed and dried, and the dentin adhesive Single Bond (3M ESPE, St Paul, MN, USA) was applied. The teeth received intracanal fiber-reinforced resin (Ribbond Triaxial, Seattle, WA, USA) fixed with a flowable composite and the crowns were reconstructed with microhybrid composite resin (Z250, 3M). All restorations were evaluated every 6 months for 30 months by 2 independent evaluators. Statistical analysis was done with McNemar's test. The surface textures for most of the restorations were judged as excellent. There was no evidence of significant changes in marginal integrity. Most restored incisors (81%) received an Alpha rating for retention. The baseline and recall retention scores differed significantly (p=0.002). Polyethylene fiber posts associated with extensive composite restoration showed excellent clinical performance after 2.5 years in primary anterior teeth after pulp therapy.

WEARABLE PERSONAL SOUND DELIVERY APPARATUS

A personal sound delivery apparatus which can be worn by a person has speakers held close to the ears and does not include any insert into the auditory canal or any ear muff that could muffle or suppress other ambient sounds. In a preferred embodiment of the invention, a wireless speaker is anchored by an arcuate hanger shaped and dimensioned to rest behind the ear. The speaker is positioned within a range from 0 to 20 centimeters (0 to 8 inches) from the auditory canal and may be surrounded by baffles that focus the incoming sound toward the entrance of the auditory canal. In other embodiments, a pair of speakers are embedded into the collar of a garment, a scapulary that rests upon the shoulders, a clamp that is bridging the nape of the neck, in pendants suspended from the neck, or hidden in a pair of earrings.

Wide band pressure and velocity (p-v) tympanometry with calibrated sound intensity micro-probes

Wide band p-v tympanometry can be defined as the measurement of the acoustic immittance of the ear, possibly in normal air pressure condition of the ear canal, and in the full audio frequency range. The most important innovation pioneered by the p-v tympanometry regards the introduction of a different principle of measurement based on the direct acquisition of, both, pressure and velocity (p-v) signals at the ear canal entrance. The measurement can be done by using a pre-calibrated couple of dedicated micro-sensors: an ordinary microphone and an acoustic velocimetric micro-device. This invited speech will report about wide band measurements of ear immittance functions carried out by means of a modified tympanometric probe hosting a pre-calibrated sound intensity micro-probe, and their comparison, with data obtained by standard 226 Hz tympanometry.

Chirurgie des äußeren Gehörgangs

Diseases of the external ear canal are a frequent reason for consulting the otolaryngologist. Conservative treatment is sufficient in most cases. Chronic problems of the external ear canal, however, sometimes require surgical treatment. Enlargement of the external ear canal as well as the entrance of the external ear canal are often simultaneously performed together with tympanoplasties, in order to obtain good access to the middle ear and to facilitate postoperative care. In this review, we focus on surgical techniques for different pathologies such as exostosis, stenosis, fibrosis, and tumors of the external ear canal.

홍바리, Epinephelus fasciatus 정자의 미세구조

Ultrastructural characteristics of blacktip grouper, Epinephelus fasciatus spermatozoa were investigated using transmission and scanning electron microscopy. The spermatozoa of E. fasciatus consisted of a spherical head part, a midpiece with cytoplasmic canal entrance and a flagellum with lateral fins. Internal ultrastructurally, the nucleus contains high electron dense chromatin having granular particles and has no acrosome. The centriolar complex lies outside of the nuclear fossa and it is connected by the osmophilic filaments. Also the osmophilic filaments connect between the centriolar complex and the nuclear membrane. The midpiece contains eight to nine spherical mitochondria, cytoplasmic canal and necklaces. The flagellum has a typical 9+2 axonemal structure. The lateral fins contain vesicles and a typical 9+2 axonemal structure. Consequently this study contributes to comparative grouper spermatology and provide useful systematic taxonomic characters.

Estimating head-related transfer functions of human subjects from pressure–velocity measurements

Direct measurements of individual head-related transfer functions (HRTFs) with a probe microphone at the eardrum are unpleasant, risky, and unreliable and therefore have not been widely used. Instead, the HRTFs are commonly measured from the blocked ear canal entrance, which excludes the effects of the individual ear canals and eardrums. This paper presents a method that allows obtaining individually correct magnitude frequency responses of HRTFs at the eardrum from pressure-velocity (PU) measurements at the ear canal entrance with a miniature PU sensor. The HRTFs of 25 test subjects with nine directions of sound incidence were estimated using real anechoic measurements and an energy-based estimation method. To validate the approach, measurements were also conducted with probe microphones near the eardrums as well as at blocked ear canal entrances. Comparisons between the different methods show that the method presented is a valid and reliable technique for obtaining magnitude frequency responses of HRTFs. The HRTF filters designed using the PU measurements are also shown to yield more correct frequency responses at the eardrum than the filters designed using measurements from the blocked ear canal entrance.

Attenuation of peak sound pressure levels of shooting noise by hearing protective earmuffs.

Transmission losses (TL) to highly impulsive signals generated by three firearms have been measured for two ear muffs, using both a head and torso simulator and a miniature microphone located at the ear canal entrance (MIRE technique). Peak SPL TL have been found to be well approximated by 40 ms short-L eq TL. This has allowed the use of transmissibilities and correction factors for bone conduction and physiological masking appropriate for continuous noise, for the calculation of REAT-type peak insertion losses (IL). Results indicate that peak IL can be well predicted by estimates based on one-third octave band 40 ms short L eq and manufacturer-declared (nominal) IL measured for continuous noise according to test standards. Such predictions tend to be more accurate at the high end of the range, while they are less reliable when the attenuation is lower. A user-friendly simplified prediction algorithm has also been developed, which only requires nominal IL and one-third octave sound exposure level spectra. Separate predictions are possible for IL in direct and diffuse sound fields, albeit with higher uncertainties, due to the smaller number of experimental data comprising the two separate datasets on which such predictions are based.

The “suprasellar notch,” or the tuberculum sellae as seen from below: definition, features, and clinical implications from an endoscopic endonasal perspective

The tuberculum sellae is a bony elevation ridge that lines up the anterior aspect of the sella, dividing it from the chiasmatic groove. The recent use of the endoscopic endonasal transtuberculum approach has provided surgeons with a method to reach the suprasellar area, offering a new surgical point of view somehow "opposite" of this area. The authors of this study aimed to define the tuberculum sellae as seen from the endoscopic endonasal view while also providing CT-based systematic measurements to objectively detail the anatomical features of such a structure, which was renamed the "suprasellar notch." The authors analyzed routine skull CT scans from 24 patients with no brain pathology or fractures and measured the interoptic distance at the level of the limbus sphenoidale, the chiasmatic groove sulcal length and width, and the angle of the suprasellar notch. Indeed, the suprasellar notch was defined as the angle between 2 lines, the first passing through the tuberculum sellae midpoint and perpendicular to the cribriform plate, and a second line passing between 2 points, the midpoints of the limbus sphenoidale and the tuberculum sellae. Moreover, the authors performed on 15 cadaveric heads an endoscopic endonasal transplanum transtuberculum approach with the aid of a neuronavigator to achieve a step-by-step comparison with the radiological data. The whole CT scanning set was statistically analyzed to determine the statistical interdependency of the suprasellar notch angle with the other 3 measurements, that is, the sulcal length at the midline, the interoptic distance at the optic canal entrance, and the interoptic distance at the limbus. Based on the endoscopic endonasal view and CT imaging analysis, the authors identified a certain anatomical variability and thus introduced a new classification of the suprasellar notch: Type I, angle < 118°; Type II, angle of 118°-138°; and Type III, angle > 138°. They then analyzed the surgical implications of the endoscopic endonasal approach to the suprasellar area, which could be affected by each of these structural types. The new classification identifies 3 different types of suprasellar notch and, accordingly, their surgical relevance. Above all, the authors found that the different types of suprasellar notch can affect the osteodural defect reconstruction technique, namely the positioning/wedging of the buttress in the extradural space. A precise endoscopic anatomical knowledge of the neurovascular and bony relationships--especially in cases of a less pneumatized sphenoid sinus--is crucial when approaching the anterior skull base via a transtuberculum transplanum route.

Inverse solution of ear-canal area function from reflectance

A number of acoustical applications require the transformation of acoustical quantities, such as impedance and pressure that are measured at the entrance of the ear canal, to quantities at the eardrum. This transformation often requires knowledge of the shape of the ear canal. Previous attempts to measure ear-canal area functions were either invasive, non-reproducible, or could only measure the area function up to a point mid-way along the canal. A method to determine the area function of the ear canal from measurements of acoustic impedance at the entrance of the ear canal is described. The method is based on a solution to the inverse problem in which measurements of impedance are used to calculate reflectance, which is then used to determine the area function of the canal. The mean ear-canal area function determined using this method is similar to mean ear-canal area functions measured by other researchers using different techniques. The advantage of the proposed method over previous methods is that it is non- invasive, fast, and reproducible.

Effect of Canal Depth on Sound Pressure Level Distribution in Human Bilateral Ears

This study was to measure the sound pressure level distribution by ear canal resonance in the human left and right external auditory canals (EAC). The gain for different stimulus frequencies was analyzed at four different measuring depths (0.5 cm, 1.0 cm, 1.5 cm and 2.0 cm) from the entrance of the ear canal bilaterally. Comparative evaluation showed that the gain for different stimulus frequencies at a depth of 2.0 cm was consistent with the results of Dillon’s study. In addition, the gain for the right EAC at 4000 Hz was larger than that of the left EAC by 1.2 dB at 0.5 cm, 1.8 dB at 1.0 cm, and 0.8 dB at 1.5 cm. This seems to suggest that gain at 4000 Hz is more affected by depth in the right EAC than in the left EAC. This study further found that the gain at the stimulus frequency of 4000 Hz was more affected by the depth than at 2000 Hz for the bilateral ear canals respectively. These gain differences between the right and left ears were statistically significant (p&lt;0.05) at any of four measuring depths. The findings of this study may have an understanding of gain distribution to have implications for microphone placement of custom-made bilateral hearing aids (i.e. ITC or CIC) as these are placed at different depths within the ear canal. Keywords: Sound pressure level; Canal depth; Ear canal resonance; Real ear measurement; External auditory canal

Geochemical behavior of heavy metals in differents environments in Rodrigo de Freitas lagoon - RJ/Brazil

The accelerated urbanisation without a planning, brought several environmental problems to Rio de Janeiro coastal zone, especially in areas such as Rodrigo de Freitas lagoon, which receives a great amount of untreated sewage every day. To assess the nature, potentially sources and extent of heavy metal pollution in the lagoon, sediments from the surrounding streets, from the entrance of the main canal that drains to the lagoon and from the bottom of the lagoon were collected and analysed by a modified selective extraction procedure in order to study the geochemical partitioning and bioavailability of Zn, Cu, Cr, Ni and Pb in these three compartments. The present study verified an increase in the Cu, Pb and Zn concentrations in the north of the Rodrigo de Freitas lagoon. Despite the different levels of oxidation between the sediments accumulated in the streets and in the bottom of the lagoon, the geochemical partitioning of the heavy metals did not show any pattern of variation for the metals, except for the element Cu. No concentrations were found in the soluble phase of samples collected in the surfacial sediments of the lagoon, suggesting no bioavailability of heavy metals.

Bony Nasolacrimal Duct Entrance Diameter: Gender Difference in Cadaveric Study

To examine gender differences in bony nasolacrimal canal entrance diameters in cadavers. Fifty-seven orbits from 29 Japanese cadavers (37 orbits from 19 men and 20 orbits from 10 women), aged 61 to 96 years at death (mean: 79.5 years; men: 77.8 years; women: 82.7 years), were fixed in 10% buffered formalin. The anteroposterior and transverse diameters of the bony nasolacrimal canal entrance were measured. The diameters were compared between genders using Student's t test. The mean anteroposterior diameters in all subjects, men, and women, were 6.9, 6.8, and 7.2 mm, and the equivalent transverse diameters were 5.7, 6.1, and 5.0 mm, respectively. There was no significant gender difference in the anteroposterior diameter (p = 0.287), but the transverse diameter was significantly shorter in women than in men (p = 0.004). The transverse diameter of the bony nasolacrimal canal entrance was significantly shorter in women than in men, which may be a possible factor contributing to the higher incidence of primary acquired nasolacrimal duct obstruction in women.

Otoacoustic emission retrograde standing waves caused by eartip foams

Travelling the retrograde path from the inner ear towards the entrance of the ear canal, otoacoustic emissions (OAE) are apt to be affected by the impedance of the eartip foam. Therefore, the purpose of this study was to determine the complex reflection coefficient at the surface of eartip foam specimens. This was carried out by means of a conventional impedance tube. Measurements were performed with a closed end as well as with an open end behind the eartip foam, the latter configuration being considered as a more realistic analogy to the in-situ performance of eartips. For both configurations of the impedance tube, a high reflection coefficient of the foam was measured, representing an acoustically rigid boundary. Retrograde OAE standing waves are, hence, anticipated when modelling the path taken by the OAE signals. These retrograde standing waves would result in an OAE node near the tympanic membrane at the quarter-wavelength frequencies of the ear canal, rendering the measurements inaccurate at that location. Recording OAEs at the entrance of the ear canal is thus preferable. Moreover, the compression of the foam eartips, evaluated using a specially designed foam specimen, proved to have no significant effect on the reflection coefficient.

Die Anlage einer selbstreinigenden offenen Mastoidhöhle

Our experience from multiple open mastoid cavity revisions is that some of the well-proven techniques to create a self-cleaning small open cavity are not anymore practiced everywhere.The crucial steps are to considerably drill down the facial ridge, as well as the lateral bone (to the level of the sigmoid sinus) and - in cases of a well pneumatized mastoid - to ground down the mastoid tip. The bony rims should be smoothened with a diamond burr. Furthermore, the size of the cavity can be reduced by partial obliteration of the retrofacial space and the sinus-dura-angle using bone substitutes. In our hands cartilage chips have proven to be a good substitute, hydroxy apatite pellets or a musculoperiosteal flap according to Palva might be used alternatively. Finally a wide auditory canal entrance has to be created. By applying these techniques, for a selected number of cases the "open technique" still represents an essential part of cholesteatoma surgery these days.

Heat and humidity buildup under earmuff-type hearing protectors

A major barrier to effective wear of hearing protection is comfort. This study examined several comfort indicators in the earmuff-type hearing protectors. Twenty subjects wore hearing protectors instrumented with two different temperature/humidity measurement systems (Omega and iButton) while walking a corridor for about 25 min. The instruments recorded the temperature and humidity every 10 s and their results were compared. In addition, skin surface pH was measured at the ear canal entrance before and after the task. Finally, the subject indicated earmuff comfort at the beginning and end of the session. Earmuff comfort decreased significantly over the course of the walking task. Ear canal pH became slightly less acidic, but the change was not statistically significant. The two temperature/humidity systems provided comparable results. Heat increased at about 0.3°F while humidity built up at about 0.5%/min. However, the study found some limitations on the instrumentation. The complexity of the electrical connections and equipment in the Omega probe system led to loss of three subject's data. The iButton device was more robust, but provided only 256 gradations of temperature and relative humidity. Even with its limitations, the iButton device would be a valuable tool for field studies. The present study showed that the buildup of heat and humidity can be modeled using linear equations. The present study demonstrates that relatively inexpensive tools and a low-exertion task can provide important information about the under-earmuff environment, which can inform assumptions about comfort during use.

A comparison of CIC and BTE hearing aids for three-dimensional localization of speech

Three-dimensional sound localization of speech in anechoic space was examined for eleven listeners with sensorineural hearing loss. The listeners were fitted bilaterally with CIC and BTE hearing aids having similar bandwidth capabilities. The goal was to determine whether differences in microphone placement for these two styles (CICs at the ear canal entrance; BTEs above the pinna) would influence the availability of pinna-related spectral cues and hence localization performance. While lateral and polar angle localization was unaffected by the hearing aid style, the rate of front-back reversals was lower with CICs. This pattern persisted after listeners accommodated to each set of aids for a six week period, although the overall rate of reversals declined. Performance on all measures in all conditions was considerably poorer than in a control group of listeners with normal hearing.SumarioSe evaluó la localización tridimensional de sonidos del habla en un espacio anecoide en once personas con pérdida auditiva sensorineural. A los once se les adaptaron CIC y BTE bilateralmente con capacidad de ancho de banda similar. El objetivo fue determinar si las diferencias en la colocación del micrófono con ambos tipos (CIC en el ingreso del conducto auditivo; BTE sobre el pabellón auricular) podría influenciar la disponibilidad de claves espectrales relacionadas con el pabellón y por ello, el rendimiento para la localización. Mientras que la localización del ángulo lateral y polar no fue afectada por el tipo de auxiliar, la tasa de inversiones frente-atrás fue menor con los CIC. Este patrón persistió después de que estas personas se acostumbraron a cada set de auxiliares por un período de seis semanas, a pesar de que declinó la tasa global de reversiones. El rendimiento en todas las mediciones y condiciones fue considerablemente más pobre que en el grupo control de personas con audición normal.

Rectal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up

Rectal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up