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Disorders of Hearing
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
Linda M. Luxon, Ronald Hinchcliffe
Pure-tone audiometry is the standard auditory test to document the threshold of hearing (British Society of Audiology, 1981). The technique, performed in a sound-proofed room according to standardized protocols, allows the severity, symmetry and configuration of any hearing loss to be defined across frequencies between 125 and 8,000 Hz in each ear. Electrically generated pure-tones are delivered by headphones, and the subject is required to respond to the quietest tone. Sound may be delivered by air conduction or by bone conduction via a bone vibrator on the mastoid process. In this latter condition, because the intra-aural attenuation for a bone-conducted sound is negligible, the ear which is not being tested must be masked with narrow-band noise centred on the test frequency. Bone-conduction thresholds, which are significantly better than air-conduction thresholds, indicate a disorder affecting the transmission of sound waves through the middle ear into the inner ear – that is, conductive hearing loss – whereas similar bone-conduction and air-conduction thresholds imply a sensorineural hearing loss (Figure 19.5). The determination of normal auditory thresholds was considered to be sufficiently important to aircrew to merit investigation. The results (Wheeler and Dickson, 1952) formed the basis for a standard (1954: British Standard 2497), and this evolved to the current International Organization Standards concerned with the effect of noise on auditory thresholds. These are dealt with in detail in Part 2 of this chapter.
Chapter 15 Audiology
Published in B H Brown, R H Smallwood, D C Barber, P V Lawford, D R Hose, Medical Physics and Biomedical Engineering, 2017
In this section an account is given of some commonly used hearing tests. In pure-tone audiometry a range of pure tones is produced and the subject is asked whether they can hear the sounds. Middle-ear impedance audiometry is another type of hearing test which enables an objective measurement to be made of the mechanical function of the middle ear. Otoacoustic emissions are a further objective measure of hearing, but the origin of these emissions is not well understood.
Experimental assessment of the effect of wearing hearing protectors on the audibility of railway warning signals for normal hearing and hearing impaired listeners
Published in International Journal of Occupational Safety and Ergonomics, 2022
Jean-Pierre Arz, Nicolas Grimault, Ossen El Sawaf
Eighty people (25 females, 55 males) aged from 18 to 81 years (M 51.6, SD 15.3) participated in the experiment. Fifty-three people were SNCF (Société Nationale des Chemins de fer Français) workers who volunteered to take part into the experiment during work-time. Twenty-seven additional participants were recruited and paid an hourly wage for their participation. The participants’ absolute hearing thresholds were measured performing pure-tone audiometry at the 11 standard audiometric frequencies from 125 to 8000 Hz (see Figure 2). The participants were then distributed into five different hearing classes according to their absolute thresholds. The participants from the first class were considered NH listeners and had absolute thresholds below a hearing level of 20 dB from 125 to 8000 Hz for both ears. Eighteen participants were considered NH listeners. The remaining participants were distributed into four additional classes depending on their average absolute threshold at 500, 1000 and 2000 Hz for the best ear, noted pure-tone average (PTA) and expressed in decibels of hearing level. Four classes of HI listeners were then considered, as follows: HI1: 10 < PTA ≤ 20 dB, 22 listeners;HI2: 20 < PTA ≤ 30 dB, 18 listeners;HI3: 30 < PTA ≤ 40 dB, 14 listeners;HI4: PTA > 40 dB, 8 listeners.
Obstructive sleep apnea risk and hearing impairment among occupational noise-exposed male workers
Published in Archives of Environmental & Occupational Health, 2023
Seunghyeon Cho, Won-Ju Park, Ji-Sung Ahn, Dae-Young Lim, Su-Hwan Kim, Jai-Dong Moon
All subjects underwent pure-tone audiometry while avoiding noise exposure for >14 hours. The avoidance of noise exposure was reconfirmed based on the work schedule provided by the company. Hearing thresholds at 1, 2, 3 and 4 kHz for each ear were determined. Pure-tone audiometry was performed by qualified audiometrists using a Madsen Itera II (Otometrics, Denmark) audiometer with TDH-39P headphones. An audiometric device was calibrated annually according to the KOSHA guidelines for audiometry.23 And it passed quality control of audiometric devices conducted by KOSHA every two years.