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Human and Biomimetic Sensors
Published in Patrick F. Dunn, Fundamentals of Sensors for Engineering and Science, 2019
Both the sensors for hearing and for equilibrium are located within the ear, as depicted in Figure 3.6. The external section of the ear (the outer ear, or pinna, and the ear canal) functionally directs sound waves to the eardrum (the tympanic membrane). This membrane covers the entrance to the middle ear. The middle ear houses three bones (the malleus, which is connected to the eardrum, the incus, and the stapes, which is connected to the oval window of the inner ear). This system of bones transduces sound waves into minute mechanical vibrations. The middle ear is filled with air that is provided by the collapsible eustachian tube, which is connected to the pharynx. The mechanical vibrations of the oval window’s membrane set up pressure waves within the fluid contained in the cochlear duct of the inner ear. These waves eventually stimulate hearing sensory hair cells. Also within the inner ear is the fluid-filled vestibular apparatus. This contains the semicircular canals responsible for equilibrium.
Hearing, Proprioception, and the Chemical Senses
Published in Robert W. Proctor, Van Zandt Trisha, Human Factors in Simple and Complex Systems, 2018
Robert W. Proctor, Van Zandt Trisha
The eardrum separates the outer ear from the middle ear. The function of the middle ear is similar to that of the eardrum: the transmission of vibration further (deeper) into the structures of the auditory system. The middle ear passes the vibrations of the eardrum to a much smaller membrane, the oval window, which provides entry into the inner ear. The transmission between these two membranes occurs by means of three bones, which collectively are called the ossicles. Individually, these bones are the malleus (hammer), incus (anvil) and stapes (stirrup), in reference to their appearance. The malleus is attached to the center of the eardrum, and the footplate of the stapes lies on the oval window, with the incus connecting the two. Movement of the eardrum thus causes movement of the three bones, which ultimately results in the oval window vibrating in a pattern similar to that of the eardrum. Typically, the role of the ossicles is described as one of impedance matching. The inner ear is filled with fluid. If the eardrum were given the task of transferring vibrations directly to this fluid, the increase in density from air to fluid would damp the incoming sound waves, reducing their amplitude. The transmission of the waves through the eardrum and ossicles to the smaller area of the oval window serves to amplify the wave, so that the change in medium from air to fluid occurs efficiently.
Chapter 3 Physics of the Senses
Published in B H Brown, R H Smallwood, D C Barber, P V Lawford, D R Hose, Medical Physics and Biomedical Engineering, 2017
The outer ear consists of the pinna and the ear canal, the inner boundary of which is the eardrum. The pinna (external auricle) of the human serves little useful purpose—apart from being somewhere to hang the spectacles and miscellaneous decorative devices. In some animals the shape is such that it funnels sound into the ear; in some, such as the elephant, a very large pinna provides a high surface area to serve as a heat exchanger. The ear canal (auditory canal, external canal) is roughly the shape of a tube, approximately 30 mm in length and 6 mm in diameter. The air in a tube will resonate at particular frequencies determined by the length of the tube and by the boundary conditions at the ends of the tube (see figure 3.13). The ear canal is closed at one end, by the eardrum, and open at the other.
Anthropometric analysis of 3D ear scans of Koreans and Caucasians for ear product design
Published in Ergonomics, 2018
Wonsup Lee, Xiaopeng Yang, Hayoung Jung, Ilgeun Bok, Chulwoo Kim, Ochae Kwon, Heecheon You
Understanding of the complex shape of the ear is needed for ergonomic design of wearable ear products. Most wearable ear products such as earphones, earmuffs, earplugs, and hearing aid devices interface with the outer ear, which comprises the pinna (auricle) and the ear canal (external acoustic meatus running from pinna to the middle ear). As shown in Figure 1, the concha located in the inner part of the pinna is separated into cymba concha and cavum concha by crus of the helix (Alvord and Farmer 1997), and the ear canal is curved with two bending points (Azernikov 2010; Pirzanski 2010; Sickel et al. 2011). The anatomical and anthropometric characteristics of the ear would be effectively utilised in designing ergonomic shapes of various ear products for fit and comfort (Jung and Jung 2003; Liu 2008).