What Does a Normal Extended Audiogram Look Like?

Discussion in 'Support' started by SignalExec, Apr 19, 2018.

    1. SignalExec

      SignalExec Member

      Tinnitus Since:
      Cause of Tinnitus:
      Accoustic trauma?
      I had my hearing checked up to 14 kHz. Up to 8 kHz, my hearing was in the normal range (about -10 dB). However, at 14 kHz, the audiometrist found about - 50 dB in both ears. Nevertheless, she wrote down a note in my file saying "high-frequency hearing OK." However, my ENT said the values indicated a quite significant hearing loss in the high-frequency range.

      I was a bit confused by the contradicting interpretations of the audiometrist and the ENT.

      I have done some searching. Jilek et al. 2014 (see below) report on reference values for the dB HL for different ages/genders. It seems that once past 30, hearing past 8khz degrades rapidly. Also, the variation in HL increases rapidly (especially for high frequencies).
      From their data, it seems that -50 dB is high but not extreme. -20 dB is the average for my age (35). However, at 45 the average is -50 dB. Added to that, the standard deviation in the HL is about 10 dB at this frequency/age range. This is, 99% of the HLs lie between -40 and 0 dB.

      I've uploaded the average HL here: .

      There are tons more analyses in the paper, including a fitted model to determine age-appropriate HLs. In fact, their model provides an estimate of the hearing loss as well as its standard error. A quick calculation shows that for a 35 y old, 75% of the hearing levels at 14 kHz are expected to lie within -40 to -6 dB. That's a huge range.

      All participants in this study were otologically normal. I assume that this means no tinnitus.
      So, in sum, I think my HL at the higher frequencies is lower than average but not dramatic. One additional source of confusion is the reliability of my hearing test data. I have actually tested twice in the 125-8k range two weeks apart. This yielded a 10-15 dB increase in sensitivity. Therefore, I have the impression that the method used to measure my HL has some substantial uncertainty on it as well, possibly due to the low number of stimuli used and the fact that strictly speaking results also depend on the response threshold of the person (in other words, the analysis should be done using a signal detection paradigm).

      Still looking for insights, though. Can anybody speak to this?

      If I see the ENT again, I'll see whether I can get my hands on the rest of the audiogram to compare my numbers with Jilek for the other frequencies tested. Stupid me didn't take a pic/note of the audiogram.

      This are the paper reporting on extended audiograms:

      Jilek, M., Šuta, D., & Syka, J. (2014). Reference hearing thresholds in an extended frequency range as a function of age. The Journal of the Acoustical Society of America, 136(4), 1821–1830. https://doi.org/10.1121/1.4894719

      Edit: similar ranges are reported by Rodríguez Valiente, A., Trinidad, A., García Berrocal, J. R., Górriz, C., & Ramírez Camacho, R. (2014). Extended high-frequency (9-20 kHz) audiometry reference thresholds in 645 healthy subjects. International Journal of Audiology, 53(8), 531–545. https://doi.org/10.3109/14992027.2014.893375

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