Although there is some debate between clinicians' experience, both older and newer research suggests that testing frequencies beyond 10kHz may obtain useful information for tinnitus patients who report higher frequency pitches, difficulties with speech in noise, and may be able to reduce the rates of "idiopathic" diagnoses.
"Best-Practices" Flowchart of Tinnitus Diagnosis and Management:
https://www.tinnitusresearch.net/index.php/for-clinicians/diagnostic-flowchart
Contains comprehensive recommendations for treatments organized in a flowchart with evidence levels and further details. See attached sample at the end of these links.
Importance of Extended High Frequency Testing:
https://journals.lww.com/thehearing...Extended_High_Frequency_Audiometry_for.8.aspx
Contains research links to address concerns such as:
-Is signal energy above 8kHz important and useful for tinnitus and hidden hearing loss?
-Reliability of EHF thresholds
-Equipment limitations
-Clinic testing times
-Treatment and management strategies
Tinnitus and Range of Frequency Loss:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4438350/
Although the conclusion of this particular research project said that the exact (or close approximation) frequency of tinnitus wasn't significantly correlated with the edge of the high-frequency loss, it was reported that patients had tinnitus frequencies that were higher than the edge of the hearing loss on the audiograms. This may suggest that we can at least get some useful information through extended high-frequency audiometry. Newer research is expanding upon these findings mentioned below."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5307623/
"The findings revealed more decreased hearing sensitivity at UHFs and higher prevalence of TEOAE abnormalities in normal hearing individuals with tinnitus compared to the control group. Moreover, stronger correlation was observed between increasing UHFs hearing threshold and decreasing SNRs of TEOAEs in tinnitus group compared with the controls. Tinnitus severity was not related to UHF hearing thresholds or SNRs at all investigated frequencies. Further research is needed to understand the value of measuring OAEs and UHF hearing sensitivity in normal hearing individuals with tinnitus, and their potential advantages on clinical outcome of these patients. Furthermore, the combined use of different tests investigating cochlear function can help comprehend the role of cochlea and hair cells in tinnitus generation better."
Ultra-High Frequency Sudden Sensorineural Hearing Loss:
https://journals.lww.com/thehearing...Frequency_Sudden_Sensorineural_Hearing.9.aspx
"Tinnitus matching is typically measured at or below 8,000 Hz, particularly for tinnitus caused by noise-induced hearing loss, although tinnitus may occur above this range
Ultra-high frequency testing may provide a wider range of understanding of patient complaints in the absence of hearing loss using standard audiometry.
Audiometric testing regularly measures frequencies between 125 Hz and 8,000 Hz. Typically, most of the hearing changes occur in this range, as does tinnitus. However, a case of unilateral ultra-high frequency SSHL suggests that a near normal or normal audiogram does not always mean a lack of significant hearing loss, and extended range testing may reveal valuable information."
Hidden Hearing Loss:
http://canadianaudiologist.ca/issue/volume-5-issue-2-2018/hidden-versus-not-so-hidden-hearing-loss/
The above article suggests that "speech-in-noise" tests are more useful than typical pure-tone audiometry (only going up to 8kHz) for diagnosing problems of hearing in noisier, social environments. "Threshold assessment at high frequencies (from 10k - 20 kHz) should be considered for inclusion in test batteries when patients report difficulties understanding speech-in-noise despite audiometrically normal thresholds up to 8 kHz. Although there are no clear causal relationships between high frequency hearing and speech-in-noise test performance, high-frequency hearing loss in relatively more noise-exposed participants has been reported by multiple teams (citations 33,36,37) and may be one of the first changes among long-time users of personal audio systems.(75)... Empirical data are needed to assess this specific suggestion, and determine the strength of any potential relationships between high-frequency hearing and speech-in-noise performance. Regardless, documentation of deficits to the high frequency regions of the cochlea will provide a tool for counseling patients on the importance of protecting their ears from loud sound to reduce the risk of further damage.
Addressing Concerns of Standing Waves and Reliability Obstacles (More info found in the Hearing Journal linked above):
https://www.ncbi.nlm.nih.gov/pubmed/7642821
"Abstract: Standing waves, in the ear canal are created by the interference of two plane waves of the same frequency traveling in opposite directions. One manifestation of this phenomena is that any lateral motion of the transducer produces a change in the length of the canal and therefore, in general, a change in the sound level at the eardrum. Because of the smaller wavelength at the higher frequencies, the changes produced by movement of the transducer will be larger for the higher frequencies than for the lower frequencies. Thus, when the transducer is removed and replaced between successive threshold estimates, it is expected, from physical principles alone, that the intrasubject reliability of the estimates should be better at the lower frequencies. Previous studies, however, have shown that the intrasubject reliability of threshold estimates is nearly the same at both the low (0-8 kHz) and the high (8-16 kHz) frequency regions. A possible explanation for these anomalous results is proposed. While it is found that transducer placement increases the variability of threshold estimates more at the higher frequencies, it has also been found that conventional headphones reduce the size of the standing wave ratios compared with a hard wall termination. An additional factor is the steeper slope of the psychometric function at the higher frequencies. The combination of these factors produces a standard deviation for threshold estimates that is only about 1 dB larger at the high than at the low frequency region."
https://hal.univ-brest.fr/hal-00742225/document
"1.5. Variability of hearing thresholds:
For most audiological applications, hearing thresholds are obtained with 5-dB resolution in the 125Hz to 8kHz range. Many studies have shown good reliability of repeated threshold measurements in this conventional range[8,9]. The use of 5-dB step sizes was adopted for the majority of these reliability studies, and the variability of hearing thresholds is therefore considered to be approximately 5 dB[10].
However, studies showed that self-recording audiometry (using 1-dB step sizes) resulted in slightly more sensitive thresholds than manual audiometry (sensitivity improved of 1–2 dB) [11]. Finally, investigators have compared threshold reliability between conventional and high-frequency ranges (above 8kHz) and have reported that reliability is equally good in both ranges [12]."
Audiometry Headphones Suggested for Reliability and Repeatability:
https://en-de.sennheiser.com/audiom...-testing-closed-dynamic-ear-protector-hda-300
Extended High Frequency Reliability Across Populations:
https://www.tandfonline.com/doi/abs/10.3109/14992027.2014.893375?src=recsys&journalCode=iija20
"Objective: The aim of the present study was to study patterns in the extended spectrum of the human hearing (0.125 to 20 kHz) in order to obtain reference thresholds. Then, we compare our values with existing results at extended high-frequencies (8 to 20 kHz) in an attempt to establish new standards for potential international adoption. Design: A prospective study in a group of otologically healthy subjects. Study sample: A total of 645 subjects aged between 5 and 90 years were recruited. Pure-tone thresholds were determined for conventional and extended high-frequencies. Results: There was an increase in the hearing thresholds as a function of frequency and age. For the 20 to 69 years old group, thresholds were lower in females than in males, especially at 12.5 and 16 kHz. Our threshold values are comparable to those presented in previous studies that used different instrumentation and populations. Conclusions: When comparing different studies the hearing thresholds were found to be similar. Therefore, it would be possible to establish international standard thresholds."