As audiological testing websites and apps become more sophisticated, it's increasingly apparent that patients are using their smartphones for far more than catching Pokemon.
“There are self-tests all over the market at the moment,” said Harvey Dillon, PhD, director of the Australian National Acoustic Laboratories (NAL). “We want to make it easy to get a hearing test and shorten the gap of time between people first thinking they have a hearing problem and doing something about it.”
Yet, others are convinced that the specialized nature of audiological devices will never be replaced.
“In my view, these will never replace an audiometric evaluation with calibrated equipment and calibrated signal delivered through a specified transducer, and in a sound-attenuating chamber with minimal ambient noise levels,” shared Sandra Gordon-Salant, PhD, professor and director of the doctoral program in clinical audiology at University of Maryland.
To date, the FDA has cleared one over-the-counter, home use hearing screener. The iHear Test operates off an Internet connection, and all data is HIPAA compliant and accessible via secured login. The device meets the sound characteristics and calibration standards of the FDA.
“Becoming FDA-approved was an extensive two-year process,” acknowledged Adnan Shennib, MS, founder and CEO of iHear Medical. “To get the approval, we had to incorporate new technology not usually seen in audiology such as self-calibrating equipment. We also needed ambient noise measurement because there is no sound booth. We had to run a clinical study and ensure the background environment was sufficiently quiet, in addition to complying with regulatory issues.”
GAMIFYING HEARING TESTS
More screening apps may be on the way.
Sound Scouts, an online app for parents to detect hearing problems in an early elementary school-age child, entered the market in 2016. Sound Scouts was developed in collaboration between NAL and CMee4 Productions to diagnose hearing difficulty before a child enters school.
Intended to imitate a game, Sound Scouts features a bionic-eared dog named Patch, who uses his exceptional hearing powers to find a missing ranger in a national park. To play this game, children aged 4 years and 7 months and older are instructed to use almost any earphones–except surround sound or gaming headphones–under adult supervision. Dillon notes that the test is designed to work with headphones that are not calibrated. The adult in charge is instructed to watch a pre-game video, then do a short reference test using both ears at once.
The app, which can be downloaded from iTunes or GooglePlay, tests for speech-in-quiet, speech-in-noise, and tone-in-noise. The speech-in-quiet test is conducted separately for each ear and interpreted relative to the adult's response. The two other tests are presented at levels well above the child's threshold measured in the first test. Sounds Scouts can compare the three tests and classify the hearing loss as sensorineural loss, conductive loss, or auditory processing disorder. Additionally, Sound Scouts combines the three results to calculate an overall score, which is later displayed and sent to parents via email. Children with uncompromised hearing ability for their age receive a score of 100, with a standard deviation of 15. Those who get a score of 68-75 are advised to repeat the game. A score of less than 68 indicates a likely hearing problem.
Evaluation of the test shows that it is almost impossible for a child with thresholds poorer than 30 dB HL in either ear to score within normal limits, and very few children with thresholds better than 20 dB HL and no apparent communication problem score outside normal limits.
“When the overall score is outside normal limits, this information about the most likely cause is helpful in determining if the next step involves consulting an audiologist or medical practitioner,” Dillon explained.
CENTRAL AUDITORY PROCESSING DISORDER
Dillon noted that auditory processing disorder could be at the root of a child's hearing difficulty.
“This creates an interesting problem in testing 4- and 5-year-olds,” he said. “There are no existing tests for auditory processing disorder in children this young so how can anyone independently check whether a child needing an abnormally high signal-to-noise ratio to understand simple words really does have an auditory processing problem? Our philosophy is that if a child needs a markedly better signal-to-noise ratio than his or her peers, despite normal hearing thresholds, it's best for parents and teachers to allow for that when communicating with the child, irrespective of the precise cause of the problem.”
The cortical audiometry threshold estimator is a one-button press automatic audiometer software program that's designed by NAL to operate with the HEARLab device. According to Dillon, it will be released in late 2016, pending FDA approval. It uses brief (50 ms), narrow-band, complex tones delivered through calibrated insert phones. It measures thresholds for these tones, and uses these results to estimate behavioral thresholds for tones. Agreement between the estimated thresholds and actual behavioral thresholds is usually within 10 dB, for hearing thresholds from around 20 to 100 dB HL.
Used as a complement to auditory brainstem testing, the fully awake patient is exposed to repeated interspersed stimulus presentations from eight different stimuli (four frequencies by both ears). The test begins at 60dB HL, then, for each stimulus, automatically drops toward 20dB or ascends toward 100dB, depending on whether cortical responses are detected.
This highly automated test estimates hearing thresholds in adults and older children who are difficult to test, usually due to dementia, stroke or other disabilities or because they are feigning or exaggerating hearing loss. Current investigations are exploring possible use in infants and younger children.
VISUAL REINFORCEMENT ORIENTATION AUDIOMETER
NAL is creating a test for a younger demographic. Children as young as 7 months old to preschool age will be able to be tested with computer-assisted visual reinforcement orientation audiometry (VROA). NAL expects to make this software available via iTunes or Google Play.
The software will require the use of either calibrated insert phones or a loudspeaker, just as when VROA is performed manually, which often requires two audiologists. It has a screening mode (i.e., to know if the child can hear sounds at a predetermined level), a manual threshold-seeking mode, and an automatic threshold-seeking mode. It finds thresholds for narrow-band sounds (warble tones) and provides a measure of hearing impairment.
In this assessment, a child is introduced to stimuli at moderately high levels. Once the child identifies the sound's source, he/she is treated to a glimpse of a cartoon character. When the child's turning behavior, or orientation, becomes a conditioned response to the sound, the level of the stimulus is reduced to the screening level or adjusted downward until the minimum response level is reached, per standard VROA testing technique.
This assessment, however, is affected by the child's mood, energy level, and hunger, possibly limiting the time the child is available for testing. This is where having an expert observer and an automated system come in handy. “The tester sitting in front of the child is key to success. Their job is to maintain the child's engagement and signal whenever the child is in a suitable state for presenting sounds,” remarked Dillon.
Dillon illustrated the assessment process. “The computer decides whether to present an actual stimulus or non-stimulus catch trial, and masks the tester. The tester then signals whether the child responded. The computer tracks how many times the child responded to the trials at each level. In the fully automatic mode, it uses this information to decide when to increase or decrease the presentation level and when to halt the test or change frequencies. The audiologist can control this or just monitor the test in telehealth mode from far away. The telehealth mode can be a serious money-saver.”
ROLE OF THE AUDIOLOGIST
With the increasing effectiveness of mobile devices in diagnosing hearing impairment, and the growing popularity of virtual health professionals, will audiologists become obsolete?
Dillon doesn't think so.
“Our community is on board to the extent that online or app-based testing encourages people to come in sooner,” he stated. “Increasingly, there will be some people who can move from a self-test of some sort to a self-fitting hearing aid of some sort. However, there will always be many who need an audiologist to do the fitting, the hearing test, and help the patient become proficient with using the hearing aids or adjust their lives to minimize the impact of hearing loss.”
In the case of automated testing, audiologists may well be able to push the start button then reach for a cup of tea. “However, no test in audiology is 100 percent accurate,” conceded Dillon. “Audiologists will continue to look at the results of any test and consistencies in patient history, behavior, and other available test results. It's at the center of the audiologist's job to integrate all the information. That applies whether tests are done automatically, objectively, or by traditional manual button pressing methods. The job of the audiologist is going to get more interesting, not disappear.”