China
Africa
Explore chapters and articles related to this topic
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 human ear serves as a receiver for sound waves (see Figure 7.2). Sound is collected by the pinna, the scoop-shaped outer part of the ear. The pinna amplifies or attenuates sounds, particularly at high frequencies, and plays a significant role in sound localization. The pinna funnels sound into the auditory canal, which isolates the sensitive structures of the middle and inner ears from the outside world, thus reducing the likelihood of injury. This canal has a resonant frequency of 3−5 kHz (Shaw, 1974), which means that sounds with frequencies in this range, such as normal speech, receive a boost in amplitude. At the far end of the auditory canal is the eardrum, or tympanic membrane, which vibrates when sound-pressure waves strike it. In other words, if the sound wave is a 1 kHz tone, then the eardrum vibrates at 1000 cycles per second. Perforation of the eardrum results in scar tissue and thickening of the membrane, which reduces its sensitivity to vibrations. This in turn leads to a decreased ability to detect tones, particularly those of high and middle frequencies (Anthony & Harrison, 1972).
Sound and hearing
Published in John Watkinson, Audio for Television, 1997
Figure 1.7 shows that the structure of the ear is traditionally divided into the outer, middle and inner ears. The outer ear works at low impedance, the inner ear works at high impedance, and the middle ear is an impedance matching device. The visible part of the outer ear is called the pinna, which plays a subtle role in determining the direction of arrival of sound at high frequencies. It is too small to have any effect at low frequencies. Incident sound enters the auditory canal or meatus and vibrates the eardrum or tympanic membrane. The inner ear or cochlea works by sound travelling though a fluid. Sound enters the cochlea via a membrane called the oval window. If airborne sound were to be incident on the oval window directly, the serious impedance mismatch would cause most of the sound to be reflected. The middle ear remedies that mismatch by providing a mechanical advantage. The tympanic membrane is linked to the oval window by three bones known as ossicles which act as a lever system such that a large displacement of the tympanic membrane results in a smaller displacement of the oval window but with greater force. The area of the tympanic membrane is greater than that of the oval window, again multiplying the available force. Consequently small pressures over the large area of the tympanic membrane are converted to high pressures over the small area of the oval window.
Some audio principles
Published in John Watkinson, The Art of Digital Audio, 2013
Figure 2.7 shows that the structure of the ear is traditionally divided into the outer, middle and inner ears. The outer ear works at low impedance, the inner ear works at high impedance, and the middle ear is an impedance matching device. The visible part of the outer ear is called the pinna which plays a subtle role in determining the direction of arrival of sound at high frequencies. It is too small to have any effect at low frequencies. Incident sound enters the auditory canal or meatus. The pipe-like meatus causes a small resonance at around 4 kHz. Sound vibrates the eardrum or tympanic membrane which seals the outer ear from the middle ear. The inner ear or cochlea works by sound travelling though a fluid. Sound enters the cochlea via a membrane called the oval window.
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).
In-ear earphone design-oriented pressure sensitivity evaluation on the external ear
Published in Ergonomics, 2022
Yan Yan, Yonghong Liu, Jiang Rui, Kexiang Liu, Yujia Du, Haining Wang
The ear, which includes the external, middle, and internal ears, is an important organ in the head. Specifically, the external ear comprises an auricle (or pinna) and an external acoustic meatus (external auditory canal) (Drake, Vogl, and Mitchell 2018). Ear-related wearables can be categorised into the following based on the location: over-ear (headphones and headsets), in-ear (earphones, in-ear/in-canal hearing aids, ear plugs, canal earbuds, and canal caps), and behind-ear (bone conduction headphones, behind-ear hearing aids, and sports earphones) (Fan et al. 2019). Additionally, in-ear earphones are commonly used for real-time communication, hearing enhancement, and noise reduction in entertainment or working scenarios. Recently, true wireless stereo in-ear earphone technology has developed rapidly. However, the increased wearing time and scenarios (including jogging and walking) have led to a greater need for a well-fit, low-pressure, and highly stable experience. Previous studies on ear-related wearables reported the sense of pressure as a vital indicator of comfort. Notably, four major aspects of earplug comfort are as follows: physical, functional, acoustic, and psychological (Doutres et al. 2020). Static mechanical pressure is also one of the main attributes of physical comfort. Similarly, the four main factors related to wearing comfort include comfort, pain, pressure, and fixation (Song et al. 2020). Studies on the comfort of wearables during sleep reported less preference for devices that occupy more space in the outer ear canal with rigid parts (Röddiger, Dinse, and Beigl 2020). The pressure between the hard part of the wearables and the ear canal causes discomfort. Furthermore, a sense of discomfort and pain is a warning signal of potential danger (Xiong et al. 2010). Moreover, high pressure between the earbuds and the ear also induces the balance and locomotion sensors on the skin to trigger discomfort or pain, mainly due to a poor fit between the body and the device (Lee et al. 2017; Doutres et al. 2020). Therefore, high pressure should not be applied to ear-related devices since the sense of pressure is an essential indicator of discomfort or pain.