The role of third windows on human sound transmission of forward and reverse stimulations: A lumped-parameter approach

Abstract

The vestibular and cochlear aqueducts serve as additional sound transmission paths and produce different degrees of volume velocity shunt flow in cochlear sound transmission. To investigate its effect on forward and reverse stimulations, a lumped-parameter model of the human ear, which incorporates the third windows, was developed. The model combines a transmission-line ear-canal model, a middle-ear model, and an inner-ear model, which were developed previously by different investigators. The model is verified by comparison with experiments. The intracochlear differential-pressure transfer functions, which reflect the input force to the organ of Corti, were calculated. The results show that middle-ear gain for forward sound transmission is greater than the gain for reverse sound transmission. Changes in the cochlear aqueduct impedance have little effect on forward and reverse stimulations. The vestibular aqueduct has little effect on forward stimulation, but increasing its impedance causes deterioration on reverse stimulation below 300 Hz. Decreasing its impedance increases the excitation effect during reverse stimulation over the entire frequency, especially below 1000 Hz. Moreover, compared with the case without the third windows, the presence of the third windows has little effect on forward stimulation. Whereas, it boosts the reverse stimulation's performance below 300 Hz.

Research on coupling effects of actuator and round window membrane on reverse stimulation of human cochlea

“…Additionally, previous study has not evaluated the contribution of coupled leakage impedance. 24 The reverse pressure transfer function without considering the inefficient coupling impedance is also calculated. This case assumes perfect coupling between the RWM and the actuator, that is, the Z CL does not produce a volume velocity shunt.…”

“…In fact, due to the uneven shape of the cochlear aqueduct, its size will gradually increase from the narrowest part, which slightly overestimates Z CA . In addition, comparing with Z CL , the cochlear aqueduct considering individual differences still exhibits high impedance, 24 which makes this difference not affect the estimated value of the inefficient coupling impedance. For Z CL , it is one of the experimentally measured effects of volume velocity shunting on the ST side.…”

“…The network topology of the human ear impedance model is illustrated in the equivalent circuit model in Figure 4, which is combined with reports by different investigators, 22,28,29 and used to study the role of the third windows during the forward and reverse stimulations. 24 Briefly, the ear canal is modeled as a lossy cylindrical tube with a length of 2 × 10 −2 m and a cross-sectional area of 4.3 × 10 −5 m 2 . 38,40 The tympanic membrane is modeled as a lossless transmission line model with a characteristic impedance of 10.5 × 10 7 kg s −1 m −4 and a frequency-independent delay of 4.61 × 10 −5 s. 28 The ossicular chain is combined into a ladder network through a series of circuit elements.…”

“…5,22 On the one hand, the presence of the vestibular and the cochlear aqueducts allow the volume velocity generated by the reverse-excitation actuator to divert to these aqueducts. 5,22–24 Also, Stieger et al 5 and Frear et al 22 reported that the interface between the actuator and the RWM was incompletely coupled during reverse stimulation. Moreover, the inefficient coupling of the actuator to the RWM has a lower impedance than the vestibular aqueduct.…”

Ajuste de um modelo de parâmetros concentrados da orelha média usando diferentes funções objetivo

“…O'Connor e Puria [15] propuseram alterações nos modelos de circuitos elétricos análogos da orelha média publicados até então, e representaram a membrana timpânica como um modelo de linha de transmissão. Em trabalhos mais recentes, diversas patologias da orelha média foram modeladas por Voss et al [16] e Xue et al [17].…”