Training in Speech Audiometry
Performing aided speech testing to validate pediatric hearing devices
Description
Aided speech testing is a highly valuable method of hearing aid validation, offering powerful utility for establishing aided benefit, and can be used across a wide range of age groups with many different types and forms of speech testing available. This video explores the various different methods of aided speech testing that exist and can be applied over a wide range of different ages.
You can read the full transcript below.
Background
The next form of hearing aid validation we can think about is the use of aided speech testing in children. In audiology, there are abundant possibilities to consider for validated speech tests, with variable applicability to the pediatric population.
We'll touch on a few of the more commonly used speech tests today, but many of the tips and tricks that we discuss with these can be applied to a wide variety of other speech tests.
Benefits of speech testing
Speech testing can be performed as both a diagnostic and a validation tool, depending on what our needs are and how it's performed.
Performing speech testing unaided and aided can provide useful comparison points, which will serve as a validation tool and a counseling tool, by opening up discussion with the patient or their families about some objective and relatable benefits or limitations.
Speech testing can be performed with either live voice or via a calibrated loudspeaker. Loudspeakers are typically preferred due to the extra level of control and objectivity that this provides to our stimulus presentation levels.
However, live voice does have its place as it is a very quick and easy check to perform, and some children can be less responsive to sounds coming from a loudspeaker.
The biggest benefit of speech testing with hearing aids is its high level of validity. Hearing aids are targeted specifically at helping people to hear speech, and by using a speech stimulus, we are targeting, and therefore validating, the intervention against this specific goal directly.
Commonly used speech tests in pediatrics
So let's take a look at some of the more widely used speech tests in pediatrics.
Ling-6
The Ling-6 test is a basic speech test, which can be used to assess a child's ability to access a range of important speech sounds. The test often uses picture cards which correspond to six different key sounds being /oo/, /mm/, /ee/, /ss/, /sh/, and /ahh/. Each of these sounds corresponds to a matching card which the child is asked to point to.
With this test using speech sounds rather than whole words, it's very useful to younger children in the earlier stages of language development.
Different phonemes may be of particular importance for individual children, such as the /ss/ and /sh/ phonemes being of particular importance for a child with a high frequency hearing loss.
Ling 6 can be completed with a live voice or with a speaker. However, with this test often being a test for younger children, it's arguably much easier to perform live voice.
This test also benefits from being fairly language neutral, and the images can be changed as needed to meet the needs of most children from different backgrounds.
McCormick Toy Test
A step up in speech testing is the McCormick Toy Test, which is very widely used in the UK. The McCormick Toy Test utilizes 14 items, which are sorted into 7 phonetically similar pairs.
Each pair is chosen to target specific phonemes, such as shoe and spoon, which looks to assess the ability to differentiate the /ss/ and /sh/ phonemes similar to in Ling-6.
In this test, the child is asked to point to toys as they are called upon. Again, the toy test can be performed with either live voice or with loudspeakers to allow for greater control over stimulus presentation levels. This test is often performed at a range of different intensity levels, right down to a near whisper.
When performing McCormick toy tests, it's important to first assess the child's knowledge of the words in question. A great way to do this is by introducing the objects one by one at the start of the test and asking the child to name them, correcting them as they are required. Pairs which are unknown to the child, which is most frequently lamb and man, can be excluded from the test.
Whilst this test is only available in English, similar concepts can be applied into other languages by finding toys with phonetically similar names, such as Perro and Dinero in Spanish.
It's worthwhile exploring what options may have already been validated within the literature in the language you require and adapt your methods accordingly.
AB Short Word List
The last speech test that we will look closer at today is the AB Short Word List. This test carries slightly higher linguistic requirements than the previous two, as there is a much broader range of words being used.
The test consists of using lists of 10 words which are played to the patient either over headphones for unaided testing or via loudspeakers for aided testing.
The patient is instructed to repeat back each word after they hear it, and their response is scored from 0 to 3 based upon their accuracy. For example, looking at the list here, a response of LUCK for the word DUCK will give a score of 2 as only one phoneme was incorrect.
The final overall score can be calculated for each list by taking the total score achieved and dividing it by the maximum possible score. This is then displayed as a percentage.
The output as a percentage is very useful as we can easily compare between different conditions, such as aided or unaided, or to monitor progressive issues over time. The numerical data is also very easy for patients and their families to understand and can be a great way to counsel our patients on both the benefits and limitations of their hearing instruments.
We can also, however, look beyond the simple score value as patterns may arise, such as the patient always missing a specific phoneme. This could help us as audiologists by informing potential amplification adjustment, and then validating that adjustment after changes have been made.
Tips for effective speech testing
Now let's think about some general tips for performing good quality speech testing.
Stay aware of stimulus levels
Firstly, always be aware of the level of presentation. This can be helped through the use of a sound level meter during live voice speech testing, or by making use of pre-calibrated sound levels if coming from a loudspeaker.
You must, however, keep in mind that distance is a key factor when working with calibrated speakers, and setting up the environment correctly is therefore a vital first step in getting good, reliable presentation levels.
Watch out for visual cues
When communicating, we are all likely aware of the significant role that visual cues play. Lip reading is a subconscious cue which we all use to assist with speech understanding, and this factor is even more significant for those who have a hearing loss.
Taking steps to avoid providing visual cues is essential to improve the validity of speech testing. This can be done by covering your face with a thin fabric which has a limited impact upon the sound but will obscure the lips. Using speakers is another great way to eliminate these visual cues.
For identification tests, such as with toy tests, it is also very important to be aware of where you are looking when you are saying a target word, as we do not want to be looking directly at the target toy as you ask for it. Children are very perceptive and will often pick up on these visual cues.
Know your patient’s language
It's important to know the linguistic level of your patient and make sensible choices of speech test material based upon this. Having multiple options available to you will allow for greater flexibility, thus allowing you to better tailor your assessments to meet the needs of the patient in front of you.
Although age is a great indicator of what will be right for the patient, children develop language at very different rates and may therefore require different approaches to have success at speech testing.
If a different first language is spoken at home, it's very useful to consider using a speech test in their first language if at all possible.
If that's not possible, but the child does have limited access to the language of the test being used, just be very critically aware of the confounding factor that this may have upon your results.
Aided THEN unaided
When completing speech testing with a child who has a hearing loss, it can sometimes be sensible to perform the test with hearing aids in situ first to ensure that they are able to fully hear instructions and understand the task before performing any unaided measurements.
By performing both aided and unaided testing, we are able to achieve the purpose of validating the success or limitations of hearing amplification. Without comparing the two conditions, we are not truly validating the impact of the hearing aids directly.
Monitor for trends in results
It can be very useful to record and regularly review speech testing trends over time, as this can help to identify issues which are potentially fluctuating or deteriorating over time and help us identify the need for further investigations or changes to the patient's management.
Consider testing in noise
Speech testing is often done in quieter rooms, which is unfortunately nothing like the challenge of a noisy classroom.
As children get older, it can become prudent to consider introducing speech testing in noise in addition to standard speech tests to further explore this highly important factor.
Discuss openly and counsel effectively
When thinking about how you use the data you gather, the results of speech testing can be a highly useful tool to discuss with either the patient themselves or their family as a means of counseling. This is due to the highly relatable nature of the test and the results.
The results that we gather can help with not only demonstrating when things are going well, but also when things may not be fully meeting expectations or ambitions. Awareness of the limitation of interventions can be just as important as demonstrating the benefits in many cases.
Conclusion
Overall, we can see that speech testing is a valuable tool which should have a place in any clinic involved in the fitting of pediatric hearing aids, both as a validation and as a counseling tool.
By taking these additional steps to explore further the most important factor of accessing speech, we can be much more confident in the quality of the care that we are providing to the individual in front of us.
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