Despite overwhelming evidence in support of extended high-frequency testing, many clinicians remain limited to conventional tonal audiometry (125 - 8000 Hz). Normal hearing in the extended high-frequency range is what enables us to hear conversation in loud environments. Without it, communication in these environments becomes very troublesome.
Most young healthy people have an auditory range that reaches up to 20 000 Hz with frequencies between 9000 and 20,000 Hz being referred to as extended high frequencies (EHF).
EHF audiometry tests these extended ranges and plays an important role in monitoring the ototoxic effect of certain drugs. However, the benefits of screening and monitoring EHF goes beyond this conventional scope. Here are 5 reasons why everyone should be considering the use of EHF audiometry in daily practice.
1. EHF Audiometry Is Extremely Valuable In Early Detection Of Ototoxicity.
The usefulness of EHF audiometry is well known in the early detection of hearing loss in individuals who are being treated with ototoxic medications. These include aminoglycosides, platinum-derived chemotherapy treatments and cisplatin, which is the drug that presents the greatest risk of developing ototoxic effects. These drugs are notorious for causing permanent hearing loss which is why clinicians conduct EHF audiometry on individuals who report using the above-mentioned medications.
Of note is the ototoxic effect of over-the-counter drugs, such as Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) including aspirin, ibuprofen and naproxen. These drugs can potentially cause hearing loss in individuals, however, clinicians often don’t monitor the hearing of such individuals (possibly because the patients don’t disclose their use). This motivates for the use of EHF audiometry in every clinic to ensure early detection of possible EHF hearing loss.
2. EHF Audiometry Is More Sensitive Than Conventional Audiometry In Detecting Noise-induced Hearing Loss.
There is a paucity of literature on the possible role of EHF testing as a tool for early detection of NIHL. However, all the studies that have been published suggest the usefulness of EHF testing as the optimal tool for early detection of NIHL.
The generalization of the data derived from these studies is limited by some methodological issues, such as the low number of study participants. However, looking at all the results of the studies together, there is a general consensus in the use of EHF audiometry as a more sensitive tool to detect NIHL. Therefore, EHF testing can represent a very useful preventative measure in individuals exposed to noise in occupational settings. This includes information counselling on the use of noise protection devices and the avoidance of noisy environments.
3. Hearing Loss At Higher Frequencies (And At EHF) Can Lead To Difficulty Understanding Speech In Noisy Environments.
Frequencies ranging from 300 to 4000 Hz have been considered most paramount for understanding speech. Multiple researchers have concluded that the range of conversational frequencies of the human voice lies between 250 and 3000 Hz. However, we do know for a fact that some phonemes are located between 4000 and 8000 Hz, or even at higher frequencies, especially in fricative consonants. Therefore, the prevention and management of EHF hearing loss is of paramount importance in ensuring optimal hearing of individuals.
4. EHF Audiometry Can Help To Discover Hidden Hearing Loss.
Multiple patients walk into clinics complaining of hearing difficulties and/or tinnitus despite having hearing thresholds within normal limits. However, when EHF audiometry is performed, patients generally show a substantial hearing loss at frequencies beyond 9000 Hz. Various researchers show that when EHF hearing is lost, so is optimal hearing. This loss could explain (though sometimes partial) the tinnitus and difficulty of hearing.
How Can I Implement This Now?
If your current audiometer doesn't already have this feature, it’s time to upgrade.
When looking to buy an audiometer, it is always a good idea to find one that is upgrade-able. One that has the features you currently need but one that also allows you to upgrade without having to purchase a whole new device.
In this case, you will need the ability to test up to 16 kHz.
The KUDUwave devices can be purchased with EHF included (KUDUwave Pro) or can be upgraded to include EHF at any time.
Research the use of EHF audiometry and share this information with colleagues, customers or stakeholders.
In order to make changes in any organisation, it is always advisable to ensure that your whole team are behind the change. Buy-in from stakeholders will help you to approach this change with more realistic and collaborative goals for implementation.
Make it permanent. For all the reasons mentioned above, EHF audiometry should be established as a normal part of clinical practice. The benefits received from increased test accuracy and better patient outcomes will be felt for years to come.