Tatsuya Fukazawa

A new index for evaluation of the turbulent noise in pathological voice

The validity of the parameter Br index, which was designed as an indicator of the turbulent noise in breathy voice, was tested. The parameter was determined by the ratio between energy of the second derivative of the high-pass filtered wave and that of the nonderived high-pass filtered wave. The principle of this method is the utilization of the difference in the frequency range between the turbulent noise and other components present. The parameter was found to correlate with the perception of breathiness. Clinical applications of this index suggest the possibility of using it further as a detection tool for diseases that generate turbulent noises.

Evoked otoacoustic emissions in a nonlinear model of the cochlea.

A nonlinear, transmission-line-analog model of the ear is presented for the purpose of simulating the experimental data of delayed evoked otoacoustic emissions (DEOAEs). The model produces echoes very similar to DEOAEs in the latency, saturation and spectral features when hypothetical, highly damped points arranged on the BM with an equal spacing are assumed. Special attention is payed to the reason for the long latency of DEOAEs. In the model, the delay occurs spuriously by cancellation of components scattered from the irregular points and is longer than the simple round trip time of the travelling wave from the stapes to the place of characteristic frequency. The echoes in the model are basically linear for the low intensity stimuli and only when the stimuli surpass a certain level they saturate owing to the nonlinearity of the BM damping.

How can the cochlear amplifier be realized by the outer hair cells which have nothing to push against

A theoretical consideration is given on how the constituent cells of the cochlear partition can amplify its motion and increase its momentum without resorting to external forces, and it leads to a micromechanical model that explains the role of the cells in the active amplification. The triangle composed of the outer hair cell, the phalanx of Deiters cell and the reticular lamina forms a mechanical unit that stores up and releases strain. When outer hair cells contract in a region along the cochlear partition, strain accumulates in the triangle causing deformation of the region that pushes down the basilar membrane, and hence it appears as a transverse pressure that drives the basilar membrane. The momentum of the region increases at the cost of the momentum of neighboring regions, and the total momentum of the cochlear partition is not altered by the internal forces generated by the outer hair cells. The model can produce a frequency-response curve that compares favorably with experimental data.

The Effect of Injection of High K+ Solution into Scala Media

Thirty guinea pig ears were studied to investigate the effect of endolymphatic hydrops on the cochlea. High K(+) solution was injected into the scala media, and cochlear microphonics (CM) and endocochlear potential (EP) were observed before, during and after the injection. The CM amplitude decreased rapidly after injection, ending in a depressed plateau value. By contrast, EP remained almost unchanged. By changing the composition of the solution it was suggested that the effect of the injection was mechanical one, rather than biochemical. In three ears, spontaneous recovery of CM was observed during a relatively long interval after the injection. The meaning of these findings for the hearing loss in Menieres disease is discussed.

A micromechanical model of the cochlea with radial movement of the tectorial membrane

The function of the tectorial membrane in the cochlear micromechanics is uncertain. In modeling approaches some models have assumed it to be a resonator that participates in the sharp tuning mechanisms of the cochlea with its mass coupled to the ciliary stiffness of outer hair cells, being driven by the shear force between the reticular lamina and itself. This paper presents a different type of micromechanical model which assumes that the tectorial membrane is driven by a lymphatic fluid flow that can be shown to have a substantial radial component. It also assumes that the reticular lamina is relatively stiff and thereby restrains the top end of outer hair cells that exert a force to the basilar membrane via Deiters cells. When combined with a three-dimensional block model, it can simulate the sharp tuning mechanisms of the cochlea well.

A new microviscometer for determining the viscosity of middle ear effusion

A new microviscometer has been developed based on the capillary viscometer method. The device uses a glass sensor tube for aspirating 15-microliter samples. The relative viscosity of the samples was estimated from the negative pressure required for aspiration of the fluid. These pressures ranged widely from 1 centipoise (cp) to 10,000 cp. Measurement of the viscosity of middle ear effusions in 119 samples from 110 otitis media with effusion patients using this device revealed a close relation between their values and their gross appearance (serous less than seromucoid less than mucoid). The microviscometer is useful to determine the relative viscosity of a very small amount of fluid such as middle ear effusion.

Combined Use of Integrated Electromyography and Score Rating Method for Evaluation and Prognosis of Facial Paralysis

Degrees of peripheral facial paralysis were assessed by the paralysis score table in a modification of Mays method together with the integrated EMG method. Paralysis scores and integrated EMGs from the frontal, orbicularis oculi and orbicularis oris muscles were obtained from 68 patients with facial paralysis. A linear regression analysis was tried in the cases of complete recovery with the following equation: Y = B log X + A, where Y = percentage of paralysis score or integrated EMG, B = recovery rate, A = constant and X = days after onset. The correlation coefficient of paralysis score and the days expressed in logarithmic form was 0.979. The paralysis scores obtained showed good correlation (0.933-0.941) with the value of the integrated EMG. The paralysis score for facial paralysis was thus confirmed by the objective EMG method. Recovery process from facial paralysis can be analysed numerically by the application of linear regression analysis in both methods.

Analysis of a hoarse voice by microcomputer

New methods for computerized analysis of a hoarse voice and their clinical application for the differential diagnosis in laryngeal pathology are described. New parameters of jet noise intensity (JNI) and fundamental tone suppression (FTS), which correspond to breathiness and strainedness, respectively, revealed their usefulness in the differential diagnosis of laryngeal cancer, whiie pitch perturbation, which has been used as a parameter of roughness, was not useful for the purpose.

A Theoretical Analysis of Endocochlear Potential (EP)

我々はループ利尿剤 Lasix による内耳障害という化学反応と, EPの低下という電気現象とを定量的に結びつけるモデルを作った. まず Honrubia の等価回路を channel 化し, 1つの電流源を1つのK+ポンプと対応させた. 次に Lasix とリセプターとの化学反応およびその阻害形式に関する仮定を導入し, K+の拡散電位を併せ考慮することにより, Lasix 負荷時のEPの経時的変化を予測する理論式が導かれた.