• Journal of Clinical Otolaryngology Head and Neck Surgery
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• v.29 no.2
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• pp.235-239
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• 2018

Due to the structure with one end closed, the external ear resonance effect in which the high frequency is amplified can be generated, and the sound can be perceived well. The external ear resonance normally has a first peak and a second peak. On average, the first peak has a gain of 18.6 dB at 2620 Hz and the second peak has a gain of 18.2 dB at 4210 Hz. The resonance of the external auditory canal changes with the state of the tympanic membrane, the presence of the ventilation tube, and the structure (length, diameter, shape) of the external auditory canal. A patient with a postauricular meatomastoid cutaneous fistula was admitted to the hospital with a foreign body which is the molding of the hearing aid. After removal of the foreign body, the resonance of the external auditory canal was lost and the subjective sound cognitive ability decreased. In the case of postauricular meatomastoid cutaneous fistula, we confirmed the improvement of sound cognitive ability, the change of pure tone hearing threshold, and the change of the external ear resonance after reconstruction of the ear canal without middle ear reconstruction.

• Phonetics and Speech Sciences
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• v.1 no.3
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• pp.151-154
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• 2009

The external ear generates resonance gain because of anatomical characteristics. The ear canal resonance is influenced by the length and volume of the ear canal, the pinna, the concha cavity, the body trunk, and the speed of sound wave. This study is focus on the influence of the volume of ear canal. 17-healthy-adult (32 ears) were participated. They did not have any medical and ear disease history. The maximum resonance frequency of the ear canal was 2675 (${\pm}265$) Hz at azimuth $0^{\circ}$ and 2784 (${\pm}268$) Hz at azimuth $45^{\circ}$. The resonance gain was 18.1 (${\pm}3.9$) dB at azimuth $0^{\circ}$ and 17.9 (${\pm}3.8$) dB at azimuth $45^{\circ}$, respectively. The ear canal volume was 0.78 (${\pm}0.2$) cc and 1.32 (${\pm}0.8$) cc including static compliance. The ear canal resonance was changed depending on the ear canal volume. It was also statistically correlated at azimuth $0^{\circ}$ (p=0.038) and $45^{\circ}$ (p=0.013), respectively. The resonance gain was not correlated with the ear canal volume. The change of resonance frequency according to the ear canal volume will be useful information in the field of audiological rehabilitation especially for hearing aids fitting. In addition, we expected this study can provide the basic information for the study of the external ear resonance characteristics.

• Journal of Clinical Otolaryngology Head and Neck Surgery
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• v.29 no.2
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• pp.245-249
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• 2018

Neurilemmoma is a benign tumor that originates from the Schwann cell. It frequently occurs in head and neck regions, but neurilemmoma of external auditory canal is extremely rare. Here, we report a very rare case of 36-year-old male with a tumor located in the posterior wall of external auditory canal, preoperatively suspected as neurilemmoma originated from Arnold's nerve by temporal bone magnetic resonance imaging. The tumor mass was surgically excised and pathologically confirmed as a neurilemmoma.

• Phonetics and Speech Sciences
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• v.9 no.1
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• pp.49-53
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• 2017

Formant frequencies depend on the position of tongue, the shape of lips, and larynx. In the auditory system, the external ear canal is an open-end resonator, which can modify the voice characteristics. This study investigates the effect of the real ear on formant frequencies. Fifteen subjects ranging from 22 to 30 years of age participated in the study. This study employed three corner vowels: the low central vowel /a/, the high front vowel /i/, and the high back vowel /u/. For this study, the voice of a well-educated undergraduate who majored in speech-language pathology, was recorded with a high performance condenser microphone placed in the upper pinna and in the ear canal. Paired t-test showed that there were significant difference in the formant frequencies of F1, F2, F3, and F4 between the free field and the real ear. For /a/, all formant frequencies decreased significantly in the real ear. For /i/, F2 increased and F3 and F4 decreased. For /u/, F1 and F2 increased, but F3 and F4 decreased. It seems that these voice modifications in the real ear contribute to interpreting voice quality and understanding speech, timbre, and individual characteristics, which are influenced by the shape of the outer ear and external ear canal in such a way that formant frequencies become centralized in the vowel space.