The introduction of the electron microscope in otological research turned the interest of morphologists to study of its organization at a level beyond the resolving power of the light microscope. Since 1953, when the electron microscope was first employed by H. Engström, F. S. Sjöstrand and J. Wersäll in the study of the inner ear, a wealth of information concerning the fine structure of the inner ear has become available. The present paper were the briefly review of the principal light microscopic as well as electron microscopic observations on the cochlea, that is, organ of Corti and its supporting structure, innervation, Reissner's membrane, stria vascularis, spiral ganglion, spiral prominence, ganglion cells and others. The functional value of these fine structures was discussed and compared with what has been studied in other techniques.
The choice of a method for volume control adjustment in hearing aid usage presents serious problems. For the purpose of determining standard use of a hearing aid by young hearing impaired children, a series of investigations regarding the volume control adjustment of a hearing aid was conducted on 49 hearing impaired children who are now in normal class with hearing aid usage. We concluded as follows. (1) It is advisable that the aided threshold for pure tone does not exceed 40dB at 500, 1000Hz, and 60dB at 2000, 3000Hz (2) Hearing aids should be used positively with suitable volume control adjustment and periodical audiological follow up.
The authors found that 34.7% of person with no subjective hearing problem showed some hearing loss on their pure tone audiogram. Refering to their age, it was observed that below 40 years the incidence of the cases with hearing loss was minimal (2.5%) and independent to age, and over 40 years hearing loss appeared in increasing incidence with increasing age. The incidence was about 30% in subjects of ages between 40 and 49 years, about 60% between 50 and 59, over 90% between 60 and 69, and over 70 years all subjects showed hearing loss. The authors concluded that it must be very important to consider this fact in diagnosing the cases with hearing disturbance at the otological and/or audiological clinic.
On the supposition that the control mechanisms in cochlear level are “interaction” and “negative feedback system”, based on the morphological and physiological evidences, the mechanism of loudness-growth is analyzed by our datum of the “equal loudness contour” on sone scale for the short tone duration's function. Results are as follows: 1) Interaction and negative feedback effect are able to be caliculated quantitatively from the loudness of short tone on each intensity and duration. Interaction has no concern with the duration of the tone. However, it has linealy concern with the intensity of the tone. Summation is resulted for the tone of less than 30dB SL and inhibition for the tone of 30dB SL and more. On the other hand, negative feedback effect increases linealy as the function of product of the intensity by the duration of a tone within the range 10dB to 60dB SL. 2) As a result of the combination of two inhibitions, without pathological adaptation, it's easily understandable that every kind of recruitment (incomplete, over and delayed type or hobble effect) should be observed on the inner ear lesion. 3) To measure the slope of temporal and equal loudness curves on the short tone durations the grade and space pattern of the lesion on the cochlear receptors and innervations are brought to light, because the slope of loudness curve is variable by the temporal summation of feedback effect and the stage of loudness curve indicates the strength of the interaction.
This investigation was carried out to study auditory cortical responses that could be recorded from the scalp, dura and brain of the rhesus monkeys. In the alert monkey the averaged cortical response with the early wave components (P1 and N1) being the largest and most consistent, could be recorded from the scalp near the vertex and was maximally recorded from the precentral dura. During anesthesia the averaged cortical response could be maximally recorded from the dura over the middle portion of the superior temporal lobe. Compared with the alert state the P1 and N1 waves greatly diminished in amplitude during anesthesia, but did not change significantly in latency. On the other hand, the P2 and N2 waves greatly increased in amplitude and became longer in latency. In the alert state, scalp response thresholds were poorer than intracranial ones. Intracranial response thresholds were lowest during sedation with phencyclidine hydrochloride and progressively became worse during the anesthetized state and highest in the alert state.