Pure-tone audiometry
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (November 2014) |
Pure tone audiometry | |
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ICD-9-CM | 95.41 |
MeSH | D001301 |
Pure-tone audiometry is the main
Pure-tone audiometry procedural standards
The current International Organization for Standardization (ISO) standard for pure-tone audiometry is ISO:8253-1, which was first published in 1983.[7] The current American National Standards Institute (ANSI) standard for pure-tone audiometry is ANSI/ASA S3.21-2004, prepared by the Acoustical Society of America.
In the United Kingdom, The British Society of Audiology (BSA) is responsible for publishing the recommended procedure for pure-tone audiometry, as well as many other audiological procedures. The British recommended procedure is based on international standards. Although there are some differences, the BSA-recommended procedures are in accordance with the ISO:8253-1 standard. The BSA-recommended procedures provide a "best practice" test protocol for professionals to follow, increasing validity and allowing standardisation of results across Britain.[8]
In the United States, the American Speech–Language–Hearing Association (ASHA) published Guidelines for Manual Pure-Tone Threshold Audiometry in 2005.
Variations
There are cases where conventional pure-tone audiometry is not an appropriate or effective method of threshold testing. Procedural changes to the conventional test method may be necessary with populations who are unable to cooperate with the test in order to obtain hearing thresholds. Sound field audiometry may be more suitable when patients are unable to wear earphones, as the stimuli are usually presented by loudspeaker. A disadvantage of this method is that although thresholds can be obtained, results are not ear specific. In addition, response to pure tone stimuli may be limited, because in a sound field pure tones create
Conventional audiometry tests frequencies between 250
Cross hearing and interaural attenuation
When sound is applied to one ear the
A reduction or loss of energy occurs with cross hearing, which is referred to as interaural attenuation (IA) or transcranial transmission loss.[13] IA varies with transducer type. It varies from 40 dB to 80 dB with supra-aural headphones. However, with insert earphones it is in the region of 55 dB. The use of insert earphones reduces the need for masking, due to the greater IA which occurs when they are used (See Figure 1).[14]
Air conduction results in isolation, give little information regarding the type of hearing loss. When the thresholds obtained via air conduction are examined alongside those achieved with bone conduction, the configuration of the hearing loss can be determined. However, with bone conduction (performed by placing a vibrator on the
Pure-tone audiometry thresholds and hearing disability
Pure-tone audiometry is described as the gold standard for assessment of a hearing loss
Hearing disability is defined by the WHO as a reduction in the ability to hear sounds in both quiet and noisy environments (compared to people with normal hearing), which is caused by a hearing impairment.[17] Several studies have investigated whether self-reported hearing problems (via questionnaires and interviews) were associated with the results from pure-tone audiometry. The findings of these studies indicate that in general, the results of pure-tone audiometry correspond to self-reported hearing problems (i.e. hearing disability). However, for some individuals this is not the case; the results of pure-tone audiometry only, should not be used to ascertain an individual's hearing disability.[18][19]
Hearing impairment (based on the
Speech recognition threshold (SRT) is defined as the sound pressure level at which 50% of the speech is identified correctly. For a person with a conductive hearing loss (CHL) in quiet, the SRT needs to be higher than for a person with normal hearing. The increase in SRT depends on the degree of hearing loss only, so Factor A reflects the audiogram of that person. In noise, the person with a CHL has the same problem as the person with normal hearing (See Figure 10).[20]
For a person with a Sensorineural hearing loss (SNHL) in quiet, the SRT also needs to be higher than for a person with normal hearing. This is because the only factor that is important in quiet for a CHL and a SNHL is the audibility of the sound, which corresponds to Factor A. In noise, the person with a SNHL requires a better signal-to-noise ratio to achieve the same performance level, as the person with normal hearing and the person with a CHL. This shows that in noise, Factor A is not enough to explain the problems of a person with a SNHL. Therefore, there is another problem present, which is Factor D. At present, it is not known what causes Factor D. Thus, in noise the audiogram is irrelevant. It is the type of hearing loss that is important in this situation.[20]
These findings have important implications for the design of
Audiograms and hearing loss
The shape of the audiogram resulting from pure-tone audiometry gives an indication of the type of hearing loss as well as possible causes. Conductive hearing loss due to disorders of the middle ear shows as a flat increase in thresholds across the frequency range. Sensorineural hearing loss will have a contoured shape depending on the cause. Presbycusis or age-related hearing loss for example is characterized by a high frequency roll-off (increase in thresholds). Noise-induced hearing loss has a characteristic notch at 4000 Hz. Other contours may indicate other causes for the hearing loss.
See also
- Hearing range
- Auditory masking
- Auditory filters
- Absolute threshold of hearing
- Equal-loudness contours
- Pure tone
References
- ^ Audiology Pure-Tone Testing at eMedicine
- OCLC 704384422.
- ^ )
- S2CID 12200368.
- PMID 25425895.
- PMID 26924453.
- ^ "ISO 6189:1983". Retrieved 18 November 2019.
- ^ Recommended Procedure: Pure-tone air-conduction and bone-conduction threshold audiometry with and without masking (PDF). Bathgate, UK: British Society of Audiology. 2011. Retrieved 18 November 2019.
- ^ http://www.emedicine.com/ent/topic311.htm [Accessed on 27/02/07]
- ^ http://michiganotoplasty.com/understanding-deafness-pta-testing/ Archived 2015-07-22 at the Wayback Machine [Accessed on 07/18/15].
- ^ "Hearing Testing and Screening in Young Children". patient.info. Retrieved 16 November 2014.
- PMID 17221060.
- ^ a b Katz J. Clinical Handbook of Audiology. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2002.
- PMID 16424946.
- ^ Sindhusake D, Mitchell P, Smith W, Golding M, Newall P, Hartley D, et al. Validation of self-reported hearing loss. The Blue Mountains Hearing Study. Int. J. Epidemiol. 2001;30:1371-78.
- ^ "Deafness and hearing loss Fact sheet N°300". WHO (World Health Organization). Retrieved 16 November 2014.
- ^ "Sound Advice". Sound Advice Safety and Health Ltd. Retrieved 10 May 2016.
- ^ Hietamen A, Era P, Henrichsen J, Rosenhall U, Sorri M, Heikkinen E. Hearing among 75-year old people in three Nordic localities: A comparative study. Int. J. Audiol. 2004;44:500-08.
- ^ Uchida Y, Nakashima T, Ando F, Niino N, Shimokata H. Prevalence of Self-perceived Auditory Problems and their Relation to Audiometric Thresholds in a Middle-aged to Elderly Population. Acta. Otolaryngol. 2003;123:618-26.
- ^ PMID 670550.
External links
- EMedicine.com.
- Pure Tone Audiometry: What is Pure Tone Average (PTA) Test?.
- Springerlink.com.
- Audition Cochlea Promenade oreille ear organ Corti C.R.I.C Montpellier. This website provides excellent diagrams and animated pictures that aid understanding of the topics covered. There are a wide range of topics covered including sound, cochlea, Organ of Corti, hair cell pathology and audiometry.
- Audiology Resources. This site provides useful resources for people interested in audiology.
- [1] This site provides excellent information regarding the Audiometric Testing procedure
- World Hearing Day 2019- Check your Hearing materials and hearing test app