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Applications of spatial sound and related problems
Published in Bosun Xie, Spatial Sound, 2023
A cochlear implant is a treatment for severe-to-profound sensorineural hearing loss caused by cochlear lesions. It captures sound signals through a microphone, converts them into certain encoded electrical signals by signal processing devices, and stimulates the auditory nerve directly through the implanted electrode array to restore or reconstruct hearing. Bilateral cochlear implants may also be thought of as a special “binaural recording and reproduction” system. The electrode system, not the headphone, serves as the transducer in “reproduction.” Transducers display electrical signals rather than acoustic signals. Similar to the case of binaural hearing aids, bilateral cochlear implants (for patients with severe bilateral hearing loss) or unilateral cochlear implants combined with the residual hearing in the contralateral ear can restore or improve the ability of binaural hearing. However, bilateral cochlear implants also suffer from the problems caused by binaural hearing aids. More importantly, limited by technology, some simplification and approximation have been made in the signal processing strategy in artificial cochlea so that the temporal envelop information of sound is preserved and the final detail of sound is lost. Therefore, this signal processing strategy can preserve ILD information at most and lose low-frequency ITD information (Laback et al., 2015; Kan and Litovsky, 2015). However, further studies should be conducted to improve the performance of artificial cochlea in the rehabilitation of spatial auditory ability.
Flexible Electronic Technologies for Implantable Applications
Published in Muhammad Mustafa Hussain, Nazek El-Atab, Handbook of Flexible and Stretchable Electronics, 2019
Loss of any sensory organ of the body leads to several challenges in one’s life. Hearing loss is one such example where it can be either conductive, sensorineural, or a combination of both. The mechanism of hearing is through conduction of bones that transfer sound waves to the inner diaphragm and nerves translate these signals to the brain. Hearing loss can be due to age (presbycusis) which is a conductive loss as sound signals are not able to pass to the inner ear from the outer ear. The sound diminishing factors can be stiffening of the eardrum, thereby losing its elasticity, loss of mobility of conducting bones becoming rigid in their action. Whereas the damage of inner ear sensory hair cells or auditory nerve damage causes sensorineural deafness. For all such cases, cochlear implants are used externally for external applications. Preliminary work on a cochlear implant had begun in the 1960s, the first neural interface designed to revive the hearing for clinically deaf representing the first successful integration of stimulation electrodes within the peripheral nervous system (PNS) (Macherey and Carlyon 2014; Jalili et al. 2017). Cochlear implants are essentially used to bypass the sound signals from hair cells by inserting electrodes into the inner ear and directly stimulating the auditory nerve in response to the incoming audio signal from a microphone placed in the external ear area.
Medical device implants for neuromodulation
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
The cochlear implant is the first example of a neural medical device that could substitute for a sensory body part, namely, the ear. A cochlear implant is an electronic device that provides the perception of sound to a person who is hard of hearing or deaf. In normal hearing, sound pressure waves travel down the ear canal, causing the eardrum to vibrate. The vibrations are transmitted to the cochlea by small bones of the middle ear, and these mechanical vibrations are transduced into action potentials that propagate to the brain, producing the perception of sound. The aim of a cochlear implant is to mimic the filtering normally performed by the bypassed portions of the auditory system. The cochlear implant dates to 1957, when Djourno and Eyriès evoked sound sensations in a deaf listener using an electrode implanted in the inner ear. Subsequently, the first commercialized multielectrode cochlear implant was implanted in 1978.
Biological function simulation in neuromorphic devices: from synapse and neuron to behavior
Published in Science and Technology of Advanced Materials, 2023
Hui Chen, Huilin Li, Ting Ma, Shuangshuang Han, Qiuping Zhao
As with retina and tactile neurons, auditory neuron is also one of the most important and efficient sensory system for our human beings that can detect, process and store the acoustic signal. In the auditory pathway (Figure 10(a-i)), auricle collects the external acoustic signal and then causes the eardrum to vibrate. After amplified by the ossicular chain, the vibrate is transmitted to the inner ear. When sound or vibration reaches the cochlea, it is converted into electrical signal by the hair cells. After that, the electrical signal is transferred to the neural center that integrates, analyses and stores the massive information [136,137]. The pathway for the acoustic signal in biological system will inspire us to exploit the artificial auditory neurons. For example, Wan et al. [112] reported a series of capacitively coupled multiterminal neuro-transistors based on the proton-conducting solid-state electrolyte film to realize spatiotemporal information processing by mimicking the dendritic discriminability of different spatiotemporal input sequences. Resulting from this processing, sound location functionality of the human brain was also emulated on the multiterminal neuro-transistors. Wu et al. [138] developed a neural network architecture based on HfOx memristor array with the function of handling complete sound signals received by two artificial ears.
Semi-automatic 3D reconstruction of middle and inner ear structures using CBCT
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Florian Beguet, Thierry Cresson, Mathieu Schmittbuhl, Cédric Doucet, David Camirand, Philippe Harris, Jean-Luc Mari, Jacques de Guise
The inner ear is a labyrinthine space with a typical length and width of 20 mm and 13 mm, respectively. This space is composed of a vestibule, a cochlea and semicircular canals (Figure 1a). The vestibule determines the orientation relative to gravity by detecting linear accelerations and the semicircular canals provide information on the inclination by detecting the rotational movements. The cochlea is the hearing organ and converts mechanical vibrations into nerve signals transmitted to the central nervous system. Since it is a major organ of hearing and balance, an anatomical knowledge of the inner ear is crucial for various research fields including cochlear implants (Razafindranaly et al. 2016), congenital malformation (Levent and Isil (2002)) and scoliosis investigation (Patten and Moldovan 2011).
Evaluating the effect of multi-sensory stimulations on simulator sickness and sense of presence during HMD-mediated VR experience
Published in Ergonomics, 2021
Simone Grassini, Karin Laumann, Virginia de Martin Topranin, Sebastian Thorp
The auditory system is also widely involved in exploring and navigating through the environment; the ability to correctly localise sounds is an important tool to explore real and virtual environments. Through the basilar membrane in the cochlea, sound waves are converted into mechanical signals and then to electrical signals that various brain centres use to compare with incoming signals from both ears and localise the sounds. As an example, it has been shown that blind people can construct coherent spatial mental maps by using just virtual navigation with acoustic information (Picinali et al. 2014). Even though auditory cues are not part of the sensory conflict theory, there are evidences that auditory cues may contribute to SS (Keshavarz et al. 2014).