Over the last decade, progress in the field of smartphone technology has seen the emergence of numerous smartphone- or tablet-based audiometer applications, also known as mobile hearing apps. While these may be beneficial for hearing test screening in portable audiometry, audiologists and occupational healthcare practitioners need to be aware of the limitations of smartphone screening audiometers.
Read on as we explore the pros and cons of mobile hearing apps, and examine some reasons why results from these smartphone-based applications should not just be taken at face value.
What Is a Smartphone Screening Audiometer, or Mobile Hearing Test App?
This type of audiometer is essentially a software application, downloaded onto a tablet or smartphone. It mimics the workings of an audiometer by offering tones of varying intensity across the frequency spectrum.
Usually, with mobile hearing apps, supra-aural headphones like the Sennheiser HD 202 II are utilised as transducers. These mobile hearing apps have been attracting a lot of attention in recent times, especially when it comes to school-based hearing screening programmes.
Currently, the various types of audiometers available on the market include:
- The traditional audiometer (which is used in a stationary audiometric sound booth)
- Boothless audiometers such as the clinically validated, telemedicine-enabled diagnostic Kuduwave portable audiometer
- Smartphone-based audiometers (also known as mobile hearing apps)
However, where precisely mobile hearing apps fit into the field of audiology is still a topic of much debate.
Why Hearing Test Results Obtained By a Mobile Hearing App Should Not Be Taken at Face Value
Several studies have been conducted to assess the validity and accuracy of pure-tone air-conduction hearing testing while using mobile hearing apps (as compared to the use of standard, or conventional audiometers), often with very different outcomes.
For the most part, evidence from studies on this topic has shown that the accuracy of mobile hearing apps is heavily influenced by the environment in which testing is conducted (referred to as the testing environment).
For this reason, the test results obtained by a mobile hearing app should not be taken at face value.
As their accuracy, reliability and test results have been proven to vary dramatically, let’s explore some more compelling reasons why the results from mobile hearing apps are not to be trusted.
1. Mobile hearing apps can over predict hearing loss at lower frequency levels
In one study, approved by the Texas Tech University Health Sciences Center (TTUHSC) Institutional Review Board, the uHear mobile hearing app was found to be “reliable at 2,000 Hz, 4,000 Hz, and 6,000 Hz”. However, when compared with standard audiometry, the application over predicted hearing loss at the lower frequency levels of 250 Hz, 500 Hz, and 1,000 Hz . The over prediction of hearing loss at lower frequencies is not surprising, as many headsets offer inadequate attenuation of low-frequency ambient noise.
Over prediction of hearing loss in screening settings may lead to over referrals and unnecessary emotional burden on the patients.
2. Mobile hearing apps cannot be used in isolation to define the hearing profiles of patients
Mobile hearing apps can be utilised as an initial screening tool for patients who believe that they may have some degree of hearing loss. However, patients should always follow up such a test with a visit to a qualified hearing healthcare professional for a full diagnostic audiometric assessment.
Mobile hearing apps are not designed for diagnostic purposes and thus cannot be used in isolation to define the hearing profiles of patients.
3. Use of mobile hearing apps can lead to inaccurate audiometric measurements and false results
In the traditional hearing assessment, a trained clinician collects audiometric data. It is the concern of the hearing healthcare community that patients will rely on the results of the mobile hearing app they used, instead of seeking professional help for their hearing healthcare concerns.
The use of mobile hearing apps by the general population, as mentioned above, can prove useful as an initial screening tool. However, because of the lack of appropriate training in administering audiometric tests by the general population, the use of mobile hearing apps can lead to inaccurate audiometric measurements and, in turn, to false results and referrals.
4. Smartphone-based hearing applications do not take into consideration bone-conduction testing or masking
While mobile hearing apps allow for air-conduction hearing testing, they do not take into consideration or offer bone-conduction testing or masking. While some mobile hearing apps have an option to test speech in noise, it does not offer the user a true masking of either ear.
In diagnostic audiometry, the use of bone-conduction testing and masking provides an accurate picture of the site of lesion or simply indicates “where the problem is” in the auditory system; and masking allows for ear-specific results. Both bone-conduction testing and the use of masking contribute to the clinical validity of diagnostic audiometry.
5. Mobile hearing apps do not feature diagnostic testing capabilities
Smartphone-based hearing applications only have screening capabilities and lack diagnostic capabilities. For an audiometer to be considered diagnostic, it has to satisfy a number of requirements.
A diagnostic audiometer measures air and bone conduction threshold levels, with some diagnostic audiometers also measuring speech threshold levels. Diagnostic audiometers indicate specifically where hearing loss has occurred.
A screening audiometer will only alert you to potential hearing issues, whereas a diagnostic audiometer will specifically identify hearing issues.
6. Transducers not built to attenuate ambient noise cannot accurately identify hearing loss below 25 dB HL
Tones presented at any intensity less than 25 dB HL are very soft and thus can be easily affected or masked by ambient (background) noise. As a result, mobile hearing apps that make use of transducers not built to attenuate ambient noise cannot accurately identify hearing loss < 25 dB HL. When seeking hearing thresholds < 25 dB HL, it is important that the test environment is accurately treated or that the tester is using transducers with greater ambient noise attenuation, to ensure that ambient noise does not mask tones presented with intensity < 25 dB HL.
7. Use of mobile hearing apps presents questions regarding continuum of care (once hearing loss has been identified)
One of the principles in hearing screening is that facilities for diagnosis and treatment should always be available. While (screening) smartphone-based applications usually serve only to detect possible hearing loss, with provision of information on causes and treatment options, some of these apps include location-based referral options in partnership with audiological societies.
However, most people with hearing loss reside in regions that have minimal access to hearing professionals, which is not an ideal situation and an area of concern.
8. There’s growing general concern around smartphone-based hearing applications and their unstandardised approach to reporting, as well as issues concerning data security
Guidelines to report on mHealth interventions, such as the mHealth evidence-reporting and assessment checklist, are becoming increasingly important for comparability and quality of evidence. Vendors and providers do not always ensure that their apps are compliant with security requirements in their jurisdiction. As a result, in terms of data security, mHealth apps are often targeted for patient data theft, as is the case for electronic health record systems.
Clinical smartphone apps for medical evaluations require health data security specified in the regulatory process required for medical certification. Ideally, mHealth apps for hearing tests must be evaluated against their intended use, consumer or clinical, and be scrutinised for data security and privacy before use.
Smartphone-based Apps Are Best Used Only for a Screening Hearing Test
Unlike the Kuduwave portable audiometer, smartphone-based applications cannot serve as a substitute for standard audiometric testing carried out by a qualified audiologist
There appears to be consensus that, based on various validation studies and current data, mobile hearing apps are best used only for screening purposes, and only in settings where more comprehensive hearing healthcare services are not available.
It is always advisable that, should a hearing problem be detected, a referral for a full diagnostic examination with a clinically validated audiometer is provided. When it comes to abnormal audiometric screening in adults, formal diagnostic audiometry is absolutely crucial.
Why Diagnostic Portable Audiometers Like eMoyo’s Kuduwave Are Essential
As human beings, a sense of belonging is one of our deepest intrinsic needs. Sadly, hearing loss, the most common disabling condition worldwide, is depriving millions of people of this vital assurance. A 2018 global estimate by the World Health Organisation indicated that approximately 460 million people worldwide (about 5% of the world’s population) are living with disabling hearing loss. Of these, approximately 7% are children.
Many people affected by hearing loss reside in middle and low income countries, where access to hearing healthcare services is not always easily available. A shortage of hearing healthcare professionals as well as reliable, high-quality audiological equipment simply exacerbates this problem.
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