The most commonly used test for evaluating auditory sensitivity among people of almost all-ages is pure tone audiometry. This method has been proven to be reliable in measuring hearing, especially in adults. While pure tone audiometry can be used in very young children and in adults, it is unreliable when used to test children or adults who may not understand instructions.
In addition, in some settings (such as school-based and industrial audiology hearing screening) bone conduction is not incorporated into the test battery, which makes it impossible to determine the site of lesion and direct referral path way.
Pure tone audiometry in isolation is not the only answer for hearing healthcare services. Below I will discuss various examples showing the importance of tympanometry, and what difference the test can make in your clinic.
Limitations of Pure Tone Audiometry in isolation
Various school-based hearing screening guidelines, such as those by the American Speech Language and Hearing Association (ASHA), World Health Organisation (WHO), and the American Academy of Audiology (AAA) have recommended screening down to 25 dB, especially in developing countries.
A higher screening intensity is often used in order to negate the effects of presence of adverse background noise. You might say that the screening intensity, to some extent, makes perfect sense. However, we know that hearing profiles among children with middle ear infections typically ranges between 15-50 dB HL across frequencies of 0.5-4 kHz, therefore, a child with thresholds of 20 dB HL across frequencies and is considered having passed, may have ear infections that will possibly be missed. In a sense, this child would be falsely passed.
Remember, early identification and intervention of hearing loss is essential in ensuring optimal development in children.
In another scenario, when you look closely at ASHA guidelines with reference to children between seven months up to three years of age, the role of an audiologist has been stressed. Screening younger children’s hearing is not easy, certainly someone with little experience (e.g., a nurse, a volunteer) may have a hard time obtaining reliable threshold from younger patients.
Thus, ASHA stressing the role of an audiologist. What makes complying to these guidelines difficult is the lack of audiologists in many of these facilities where these children are located and require the services. As such, many children may be left misdiagnosed. What further aggravates the problem is the conduction of only air conduction audiometry by the non-audiologist personnel. This results in referrals that may likely delay intervention of whatever the cause of the hearing loss may be in the child.
In most industrial audiology/ occupational health programs, professionals with training in audiometry (also known as audiometrists) are responsible for providing hearing conservation services. The test battery in this case includes solely otoscopic examination and air conduction audiometry testing.
The negligence of bone conduction (BC) is as a result of lack of training in BC testing by audiometrists or non-audiologists, the complexities of BC testing, and to possibly to save testing time. If the the results yielded by the personnel show hearing deterioration, the patient would be referred to the audiologist for further evaluation to determine the site of lesion. Such ‘indirect’ referrals usually result in delayed intervention and high costs.
Misdiagnosis of hearing loss poses a threat to the effectiveness of any hearing screening program. By incorporating tympanometry in hearing healthcare services (especially those that do not incorporate bone conduction testing), diagnosis and a more restrictive and direct referral system can be implemented. Allowing for a much more effective and time-saving intervention.
Tympanometry is well known to have a multitude of advantages for use in hearing healthcare clinics. Its is a highly sensitive and objective indicator of middle ear status, often revealing abnormalities not visible with otoscopic examination.
While pure tone audiometry is a subjective test requiring active participation of the patient and threatens the reliability of test results, tympanometry is an objective test requiring no active participation from the patient and vastly increases the reliability of results.
In pure tone audiometry, where the clinician may not be skilled to observe false positive responses, or if the device use is not like the KUDUwave which can provide patient response statistics, one may yield false results as a result of the patient not understanding the test requirement.
Advantages of tympanometry
- It is an objective test
- It is non-invasive
- Can assess patients of all age groups
- Sensitive to middle ear abnormalities
- Quick to yield results (may take less than a minute for both ears)
- Can be operated by less skilled personnel
But what exactly do the above advantages mean for your clinic? Well, i) tympanometry contributes to the diagnosis of middle ear infections that may be missed subjectively, ii) tympanometry indicates when a patient’s ear drum is perforated, iii) indicates eustachian tube dysfunction, iv) and ossicular discontinuity and otosclerosis.
All the above diagnosis and more can be determined in under 2 minutes, and the test can be performed at the bedside of the hospital, the clinician’s office, mines and in educational settings. Unfortunately, most tympanometry equipment are bulky, expensive, and not integrated with other audiological devices making it a mission to carry.
I have outlined good solid reasons why tympanometry should be included in your practice today, as well as reasons why you may still not have a tympanometer (i.e. not portable for the services you render).
Tympanometry is not new. It has been around clinically since the early 70s. However, the stationariness of the device confided it to mostly private audiology clinics, tertiary hospitals, specialised clinics and tertiary education institutes.
The use of both pure tone audiometry and tympanometry in conjunction has been reported to be significantly sensitive in diagnosing middle ear pathologies.
With the KUDUwave TMP, we have combined pure tone audiometry (air- and bone conduction), speech audiometry with tympanometry! A first of its kind…. Wait for it.
The KUDUwave TMP is a portable, software controlled, Type 1 aural acoustic immittance instrument (IEC 60645-5:2004) incorporated into KUDUwave Audiometers.
This device is powered by USB cables connected to your computer and displayed test measurements on the computer screen (Just as the KUDUwave audiometer). The KUDUwave TMP has two pneumatic systems (basically, one tympanometer for each ear), thereby allowing for bilateral tympanometry testing.
This device cuts testing time in half! With children, we all know that after testing one ear with tympanometry, they hardly allow you to test the other ear - with this device, you can test two ears at the same time, thus allowing you to get your results while the child cooperates! This device is light and portable, thus can be taken into schools, mines, hospitals, you name it.
Below I will indicate to you how one would use this device.
The KUDUwave TMP bilateral simultaneous tympanometry testing setup.
- The circumaural ear cups are initially placed over the subjects ears.
- The probe tip with eartips are inserted into the subject’s ear canals.
- The KUDUwave TMP earcups are finally placed over the subject’s ears and the probe tips.
It is that easy.
The software is easy to use, simple to understand and super fast.
Test left, right or both ears simultaneously and view all of the tympanograms and metrics on the single view-pane. Several tympanograms can be overlaid and you can switch between them and delete them as you see fit.
This device was recently validated against the industry standard tympanometer, and the results showed no difference between measurements yielded by the golden standard device as compared to the KUDUwave TMP. In addition to this, the KUDUwave TMP proved to yield the exact same quality tympanometry measurements in unilateral and bilateral simultaneous mode. Thus, one can confidently test both ears at the same time!