I have a question about the decibel value of the hearing threshold shift which would be classified as hearing loss. What is the minimum value in decibels that you define hearing loss? Is there general values in humans or in animals?
I’ve read that „a 20 dB loss in hearing at a single sound frequency following cisplatin chemotherapy would be classified as otoxicity” (Nature Reviews Drug Discovery | Published online 3 Nov 2016, First hearing-disorder drugs stumble). So 20 dB loss because of noise would be classified noise-induced hearing loss?
The most widely used and validated criteria for determination of ototoxic threshold shift were published by ASHA (1994). Signicant ototoxic change must meet one of the following three criteria: (a) ≥20 dB decrease at any one test frequency, (b) ≥10 dB decrease at any two adjacent frequencies, or (c) loss of response at three consecutive frequencies where responses were previously obtained. Changes are always computed relative to baseline mea- sures and must be con rmed by repeat testing, generally within 24 hours.
Hi Judith,
Here is what is considered clinically normal in Audiology (dB HL)
Normal –10 to 15 dB
Slight 16 to 25 dB
Mild 26 to 40 dB
Moderate 41 to 55
Moderately severe 56 to 70
Severe 71 to 90
Profound 91+
Source: Clark, J. G. (1981). Uses and abuses of hearing loss classification. Asha, 23, 493–500.
Hi Judit, I would like to agree with Juan and pragat, any type of hearing loss is classified as per Pragati's answer in differing degrees. However specific to hearing loss following noise exposure or drug-related hearing loss (I.e. Hearing loss following treatment with certain drugs) is measured using Ototoxicity scales which are different for different ages, and drugs used. For a more general scale see see Brock et al (1991), Chang & Chinosornvatana (2010) and for cisplatin induced hearing loss specific to Paediatric patients U can use the latest International Society of Pediatric Oncology scale for Ototoxicity. Hope you are clarified? If not, you can inbox me then I'll assist further
Dear Mukovhe Phanguphangu: Thank you for your reply! It's clear and I'm absolutely satisfied!
There are basically two Classification i.e. Goodman (1965) and Clark (1981). According to Goodman(1965), till 25dBHL one can consider Normal Hearing, But Clark (1981) modified it and according to Clark (1981) only till 15dBHL one can consider normal Hearing. More or less even ANSI (American National Standard Institute follow Clark (1981).
Many Thanks!
Yours Sincerely/Faithfully,
Himanshu Kumar Sanju
Post Graduate in Audiology(AIISH, Mysore-6)
Assistant Professor-1 (Audiology),
Amity University, Gurgaon, Haryana,
India.
There is one basilic French classification:
Normal thresholds are between( -10 to 15dB HL) for all the frequencies 125 Hz to 8000 Hz
Here is the issue. Are you concerned with hearing loss or change in hearing? In general, the Clark scales are used to define hearing loss with descriptors of severity. However, when considering a change in sensitivity due to an insult, be it a drug or noise, CDC/NIOSH considered any change of 15 dB or more at any frequency that was confirmed to be important. That is more extreme than the ototoxicity guideline of a 20-dB change for one frequency, but it is more conservative than the 10-dB change for two adjacent frequencies.
NIOSH also was concerned about the point at which the hearing sensitivity itself is important and described material hearing impairment as equal to 25-dB or greater binaural average for the frequencies of 1, 2, 3, and 4 kHz. Notice the inclusion of 3 kHz. This is a frequency ALWAYS tested for audiograms taken for occupational hearing loss prevention programs and is a frequency mandated by OSHA. Yet, it is often not tested by audiologists in clinical setting.
To be considered as hearing loss, it has to be 10 dB differences between the two ears at a specific frequency in the audiogram reading. As long as loss is noticed in any of the ears as a result of exposure to noise it is considered NIHL.
There are a large number of examples and aetiologies of hearing loss, some with demonstrable objective abnormalities, which show no anomaly on a standard pure tone audiogram. These patients get a rough deal from doctors and should not be forgotten.
In general,Goodman's classification is widely accepted to define hearing loss & its severity(>25 dB ),However as far as Cisplatin or any other drug induced hearing loss is concerned,there are several ototoxicity classification sytem depending upon the targeted population & intended purpose.The purpose needs to be clearly addressed;i.e.whether the purpose is
-To notify early stages of ototoxicity that any amount of ototoxic change is significant enough to warrant a dose limitation/modification in therapeutic regimen
or
-To decide upon therapeutic Intervention(Audiological Rehabilitation) in case of a handicapping hearing loss
SIOP(2012) scale for pediatric population & Tune grading system for adult population considered as most recent & sensitive classification system covers most of the purpose of a ototoxicity monitoring protocol.
Crundwell,2015 is a good source of related literature.
Thank You,
Regards,
Jitesh
Jitesh Prasad Sahoo
Thank you for your suggestions.
Best regards,
Judit
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