Diplacusis

Diplacusis, also known as diplacusis binauralis, binauralis disharmonica or inter aural pitch difference (IPD) is a type of hearing disorder that is the perception of a single auditory stimulus as sounds of a different pitch in the two ears. It is typically, though not exclusively, experienced as a secondary symptom of sensorineural hearing loss, although not all patients with sensorineural hearing loss experience diplacusis or tinnitus.[1] [2]The onset is usually spontaneous and can occur following an acoustic trauma, for example an explosive noise, or in the presence of an ear infection.[3] Sufferers may experience the effect permanently, or it may resolve on its own. Diplacusis can be particularly disruptive to individuals working within fields requiring acute audition, such as musicians, sound engineers or performing artists.[4][5][6]

Diplacusis of pure tones

The term diplacusis has been used in cases which people with unilateral cochlear hearing losses or asymmetrical hearing losses, the same tone presented alternately to the two ears may be perceived as having different pitches in the two ears.[7][8] The magnitude of the shift can be measured by getting the subject to adjust the frequency of a tone in one ear until its pitch matches that of the tone in the other ear. On presentation of a single tone alternating between ears (i.e. 1000 Hz left, 1000 Hz right, 1000 Hz left, ...), a given person will consistently mismatch these sinusoids the same amount between trials if doing a pitch-matching task. For example, a 1000 Hz tone in an unaffected ear may be heard as a slightly different pitch in the opposite ear, or have an imperfect tonal quality in the affected ear.

Biological explanation via theories of pitch of pure tones

There are two theories on the cause of diplacusis: place theory and temporal theory.[9] Place theory posits that the cause is looking for the edge of the wave for the pitch and could explain diplacusis as a small differences between the two cochleas.[10]

Temporal theory posits that the cause is from looking at the phase locking to tell what the pitch is. This theory has a difficult time explaining diplacusis. There are some examples of pitch which do not have an "edge" on the basilar membrane, which this would account for—e.g., white noise, clicks, etc.[10] Both theories are under debate.[11] [12]

Effects of sensorineural hearing loss

Normal human ears can discriminate between two frequencies that differ by as little as 0.2%.[13] If one ear has normal thresholds while the other has sensorineural hearing loss (SNHL), diplacusis may be present, as much as 15–20% (for example 200 Hz one ear => 240 Hz in the other). The pitch may be difficult to match because the SNHL ear hears the sound "fuzzy". Bilateral SNHL gives less diplacusis, but pitch distortions may persist. This may cause problems with music and speech understanding.

Treatment

Treatment of diplacusis includes a full medical and audiological examination that may explain the nature of the problem. If needed, amplification may relieve the symptoms of diplacusis. Therapy in helping the patient understand the cause of the symptom and tinnitus retraining may provide some relief. In at least some cases, amplification makes no difference and there is no treatment other than waiting for natural resolution. Some individuals may find the provided amplification also increases the audibility of their pitch discrepancy. If onset is linked to an underlying medical cause, i.e. sudden sensorineural hearing loss, appropriate medical treatment is recommended.

Etymology

Diplacusis is from the Greek words "diplous" (double) and "akousis" (hearing).[14]

See also

External sources
  • Diplacusis: I. Historical Review[15]
  • Turner, Christopher. "Perception of Pitch." Wendell Johnson Speech and Hearing Center, Iowa City. Dec. 2008.
  • Plack et al. (ed.). Pitch : Neural coding and perception. Springer. 2005.

References
  1. Colin, David; Micheyl, Christophe; Girod, Anneline; Truy, Eric; Gallégo, Stéphane (2016-08-18). "Binaural Diplacusis and Its Relationship with Hearing-Threshold Asymmetry". PLoS ONE. 11 (8): e0159975. Bibcode:2016PLoSO..1159975C. doi:10.1371/journal.pone.0159975. ISSN 1932-6203. PMC 4990190. PMID 27536884.
  2. Reiss, Lina A. J.; Shayman, Corey S.; Walker, Emily P.; Bennett, Keri O.; Fowler, Jennifer R.; Hartling, Curtis L.; Glickman, Bess; Lasarev, Michael R.; Oh, Yonghee (2017). "Binaural pitch fusion: Comparison of normal-hearing and hearing-impaired listeners". The Journal of the Acoustical Society of America. 141 (3): 1909. Bibcode:2017ASAJ..141.1909R. doi:10.1121/1.4978009. ISSN 1520-8524. PMC 5848869. PMID 28372056.
  3. Knight, Richard D. (2004). "Diplacusis, hearing threshold and otoacoustic emissions in an episode of sudden, unilateral cochlear hearing loss". International Journal of Audiology. 43 (1): 45–53. doi:10.1080/14992020400050007. ISSN 1499-2027. PMID 14974627.
  4. Jansen, E. J. M.; Helleman, H. W.; Dreschler, W. A.; de Laat, J. a. P. M. (2009). "Noise induced hearing loss and other hearing complaints among musicians of symphony orchestras". International Archives of Occupational and Environmental Health. 82 (2): 153–164. doi:10.1007/s00420-008-0317-1. ISSN 1432-1246. PMID 18404276.
  5. Kähärit, Kim; Zachau, Gunilla; Eklöf, Mats; Sandsjö, Leif; Möller, Claes (2003). "Assessment of hearing and hearing disorders in rock/jazz musicians". International Journal of Audiology. 42 (5): 279–288. doi:10.3109/14992020309078347. ISSN 1499-2027. PMID 12916701.
  6. Di Stadio, Arianna; Dipietro, Laura; Ricci, Giampietro; Della Volpe, Antonio; Minni, Antonio; Greco, Antonio; de Vincentiis, Marco; Ralli, Massimo (2018-09-26). "Hearing Loss, Tinnitus, Hyperacusis, and Diplacusis in Professional Musicians: A Systematic Review". International Journal of Environmental Research and Public Health. 15 (10): 2120. doi:10.3390/ijerph15102120. ISSN 1660-4601. PMC 6209930. PMID 30261653.
  7. Burns, E. M. (1982). "Pure-tone anomalies. I. Pitch-intensity effects and diplacusis in normal ears". The Journal of the Acoustical Society of America. 72 (5): 1394–1402. doi:10.1121/1.388445. ISSN 0001-4966. PMID 7175025.
  8. Burns, E. M.; Turner, C. (1986). "Pure-tone pitch anomalies. II. Pitch-intensity effects and diplacusis in impaired ears". The Journal of the Acoustical Society of America. 79 (5): 1530–1540. Bibcode:1986ASAJ...79.1530B. doi:10.1121/1.393679. ISSN 0001-4966. PMID 3711452.
  9. Oxenham, Andrew J. (2013). "Revisiting place and temporal theories of pitch". Acoustical Science and Technology. 34 (6): 388–396. doi:10.1250/ast.34.388. ISSN 1346-3969. PMC 4215732. PMID 25364292.
  10. Oxenham, Andrew J.; Micheyl, Christophe; Keebler, Michael V.; Loper, Adam; Santurette, Sébastien (2011-05-03). "Pitch perception beyond the traditional existence region of pitch". Proceedings of the National Academy of Sciences of the United States of America. 108 (18): 7629–7634. doi:10.1073/pnas.1015291108. ISSN 1091-6490. PMC 3088642. PMID 21502495.
  11. Verschooten, Eric; Shamma, Shihab; Oxenham, Andrew J.; Moore, Brian C. J.; Joris, Philip X.; Heinz, Michael G.; Plack, Christopher J. (2019). "The upper frequency limit for the use of phase locking to code temporal fine structure in humans: A compilation of viewpoints". Hearing Research. 377: 109–121. doi:10.1016/j.heares.2019.03.011. ISSN 1878-5891. PMC 6524635. PMID 30927686.
  12. Oxenham, Andrew J. (2018-01-04). "How We Hear: The Perception and Neural Coding of Sound". Annual Review of Psychology. 69 (1): 27–50. doi:10.1146/annurev-psych-122216-011635. ISSN 0066-4308. PMC 5819010. PMID 29035691.
  13. Micheyl, Christophe; Xiao, Li; Oxenham, Andrew J. (2012). "Characterizing the dependence of pure-tone frequency difference limens on frequency, duration, and level". Hearing Research. 292 (1–2): 1–13. doi:10.1016/j.heares.2012.07.004. ISSN 0378-5955. PMC 3455123. PMID 22841571.
  14. "Surgical Clinics of Chicago". California State Journal of Medicine. 19 (1): 36–37. 1921. ISSN 0093-402X. PMC 1516741.
  15. Albers, G. D.; Wilson, W. H. (1968). "Diplacusis. I. Historical review". Archives of Otolaryngology (Chicago, Ill.: 1960). 87 (6): 601–603 contd. doi:10.1001/archotol.1968.00760060603009. ISSN 0003-9977. PMID 4871882.
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