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An Introduction to Sound, Hearing and Perception
Published in Nick Zacharov, Sensory Evaluation of Sound, 2018
The conversion from acoustical vibration into neural pulses happens in the cochlea, which is a spiral-shaped and liquid-filled tube of about 2.7 turns having a length of 35 mm, as shown in Figure 3.7 (Plack, 2013). The cochlea has two membrane-covered openings to the middle ear called the oval window and the round window. The oval window routes the movements of the stapes to the liquid medium inside the cochlea. The basilar membrane is the first frequency-sensitive part in the auditory pathway. It is illustrated in the linearised model shown in Figure 3.8. The helicotrema is an opening at the apical end of the basilar membrane, which connects the liquid on both sides of the membrane. The membrane is relatively narrow, as it reaches only about 0.5 mm at its widest point, which is at the apical end (Plack, 2013).
Noise Pollution and Control
Published in Subhash Verma, Varinder S. Kanwar, Siby John, Environmental Engineering, 2022
Subhash Verma, Varinder S. Kanwar, Siby John
Within this fluid-filled cochlea, a cross-section of which is shown in Figure 38.1, is the basilar membrane, which is attached to the round window membrane. Attached to the basilar membrane are two sets of tiny hair cells pointing in opposite directions. As the round window membrane vibrates, the fluid in the inner ear is set in motion, and the thousands of hair cells in the cochlea shear past each other, setting off electrical impulses that are sent to the brain through the auditory nerves. The frequency of the sound determines which of the hair cells will move. The hair cells close to the round window membrane are sensitive to high frequencies, and those in the far end of the cochlea respond to low frequencies.
Noise and vibration
Published in Sue Reed, Dino Pisaniello, Geza Benke, Principles of Occupational Health & Hygiene, 2020
With acoustic shock incidents, the loud noises occur with rise times of between 0 and 20 milliseconds. The time for the middle ear muscles to react by contracting is about 25 milliseconds. When they do contract, they do so with added force because of the combination of loud noise and the startle reflex. In extreme cases, this may lead to a tearing of the oval or round window membrane and subsequent leaking of fluid from the cochlea.
A comprehensive finite element model for studying Cochlear-Vestibular interaction
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Junfeng Liang, Zhang Ke, Paige V. Welch, Rong Z. Gan, Chenkai Dai
All the inner ear components were meshed by brick elements. The BM was meshed by 545 solid elements, and the RM had 1139 solid elements. The other membranous and the supporting bony structure had 12,968 and 1083 solid elements, respectively. The round window membrane (RWM) and oval window membrane (OWM) were divided into 48 and 24 solid elements, respectively. The endolymph and the perilymph were meshed by 172,252 and 116,353 tetrahydric acoustic elements, respectively. The whole FE model consisted of 304,412 elements and 80,038 nodes. The number of the elements was tested by increasing the number of the element until the results did not show significantly different. The average element size of in the model is 0.26 mm. Given the sound velocity of 340 m/s, and the maximum frequency of 10,000 Hz, the minimum wavelength in the analysis is 34 mm. The element dimension is ∼0.7% of the minimum wavelength, which satisfies the requirement for the acoustic simulation.
Device profile of the MED-EL cochlear implant system for hearing loss: overview of its safety and efficacy
Published in Expert Review of Medical Devices, 2020
Uwe Baumann, Timo Stöver, Tobias Weißgerber
The procedure for the implantation of the stimulator is described in the surgical guideline [9]. Summarized, a curved incision is made in the retroauricular region, and a skin flap is prepared. After drilling the mastoidectomy followed by a posterior tympanotomy, a periosteal pocket for the implant is prepared using a periosteal elevator. An implant template can be used to mark the flatness on the skull and the correct position for the implant bed. For protection and placement of the electrode lead, a smooth channel has to be drilled in the bone leading to the mastoid. Access to the scala tympani of the cochlea is regularly established either by a cochleostomy near the round window or by opening the round window itself after preparing a clear view of the round window. Either a micro-lancette or a micro-hook can be used to open the cochlea. Then, insertion of the electrode lead should approach the anterior portion of the basal turn at an angle so that it slides along the lateral wall of the scala tympani. This procedure, known as tangential insertion, facilitates deep electrode insertion. During insertion, it is essential that the electrode contacts are not mechanically damaged and that no excessive force is used. The most commonly used technique for the fixation of the stimulator is to use a tight periosteum pocket.
Effect of ossicular chain deformity on reverse stimulation considering the overflow characteristics of third windows
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Houguang Liu, Lin Xue, Jianhua Yang, Gang Cheng, Lei Zhou, Xinsheng Huang
Hearing loss is one of the most prevalent diseases all over the world. With the growth and aging of the global population, the number of people with hearing loss is increasing rapidly. As the primary type of hearing loss, the sensorineural hearing loss still lacks effective treatment. Most patients can only use hearing aids to compensate for hearing loss (Moore 2007). However, traditional hearing aids have a series of inherent problems such as acoustic feedback, limited high-frequency gain, and ear canal occlusion (Angeli et al. 2005; Hong et al. 2007). Besides, for some patients with ossicular chain deformity (OCD), in which the sound wave cannot transmit efficiently from the tympanic membrane to the cochlea, hearing aids cannot be used to compensate for hearing loss (Colletti et al. 2013). In response to this problem, Colletti et al. (2006) proposed a method of coupling the actuator of the middle ear implant with the round window membrane to treat hearing loss. This application of the middle ear implant is also called reverse stimulation (Stieger et al. 2013), as its sound transmission path in the ear is opposite to that of the normal hearing process, in which the sound is transmitted to the cochlea through the oval window rather than the round window. Under this stimulation, the actuator transmits its vibrational energy directly into the cochlea by stimulating the round window membrane, bypassing the damaged ossicular chain. Clinical results indicate that it can effectively compensate for this kind of hearing loss (Schraven et al. 2012; Maier et al. 2013; Shin et al. 2016). However, its postoperative outcomes show large variations among patients (Sprinzl et al. 2011).