Hi again, folks. For this post, I've decided to focus on a lower-level, practical topic and a fundamental part of the traditional hearing test battery - "Word Recognition Testing (WRT)".
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If you have ever participated in a hearing test and have been asked to repeat single syllable words with prompts like "say the word love" or "say the word burn", then you've participated in a word recognition test. The purpose of this test is to measure, in terms of a percent, your optimal ability to process speech in a quiet setting. In addition to performing the test for each individual ear, some clinics also perform the test binaurally (for both ears simultaneously).
Best practices for WRT have been around for many years, are well proven and documented. They are also important enough to reiterate often, especially given the number of consumers still exposed to poor WRT practices. Further still, many professionals (and, consequently, their clients) draw improper conclusions from the test data that may contribute to a less-than-satisfactory, lower value hearing solution.
The remainder of this article discusses various important points that your hearing clinic and professional should be considering when performing the WRT. Ensure your hearing clinic performs best practice hearing tests. If not, consider choosing a quality, independent hearing clinic.
Presentation Medium & Speech Variance
Let me be blunt here. "Live voice" WRT should never be used. Only official, recorded WRT lists should be used. Studies show that discrepancies for WRT results of 50% or more exist when presenting two different recordings of the same word lists to the same clients at the same volume. Even more variance exists with the use of inconsistent live voice testing, even when using the same test voice. (Mueller, 2013)
It is impossible to say with any confidence that a change in a client's ability to process speech exists between one hearing test and the next when WRTis performed using live voice or different recorded voices. It is also equally impossible to compare your WRT results with those of "normal hearing" when testing is performed in this manner. It is important to know if your ability to process speech has changed over the years and how your hearing compares with normal hearing.
If your hearing clinic doesn't use recorded speech signals during WRT, choose a different hearing clinic.
If I present to you a list of words at a very quiet volume, then present the same list to you at a louder volume, chances are you will understand the louder list better, or at least equally as well. When WRT word lists are presented at a volume that is too low, what does that tell us? The answer is, "not much", as the purpose of the WRT is to measure your optimal speech processing ability.
The problem is that many clinicians opt for a presentation volume for WRT that is too low and will not yield the best possible score. The WRT presentation volume should always be cross-checked against audiogram measurements (pure-tone average results) to ensure the volume is loud enough to achieve the highest WRT scores possible. It is also good practice to administer the WRT at varying presentation volumes until the maximum score is achieved.
If your WRT results show low scores, ask your hearing clinic to consider verifying these results at a higher volume. If they are reluctant to do so, choose a different clinic.
Number of Words Presented
WRT word lists were never designed to be anything less than 50-words in length. Testing has shown that there is a variance of around 60% between the easiest word and the hardest word to recognize in any given 50-word list, and a 16% variance between the first 25 words as compared with the last 25 words. Commonly used 25-word lists may not reflect the same level of difficulty as 50-word lists, so their results are inconsistent. However, many clinics continue to use 25-word lists. (Mueller, 2013)
Be sure to ask your hearing clinic to test you with recorded 50-word lists. If they refuse, choose a different hearing clinic.
Statistical Significance & Interpreting Results
WRT results become more accurate and meaningful in proportion to the number of words presented. For instance, when presenting best practice 50-word lists, differences in score below 12% cannot be deemed statistically significant. For 25-word lists, this value jumps to 24%, another valid reason to avoid using them. Some hearing clinics erroneously interpret statistically insignificant percentage differences to be meaningful. This can result in unneeded physician referrals, undue worry, and improper hearing aid selection and programming. (Mueller, 2013)
If your hearing professional gives significance to differences in WRT scores of less than 12% (for 50-word lists) or 24% (for 25-word lists), whether between ear scores (for the same test) or between different test scores (for the same ear), feel free to speak up, lest assumptions be made that may not be in your best interest.
Canada is experiencing great levels of multicultural growth, especially in major urban centres, and this trend is expected to continue. Many hearing aid clients don't speak English as a first language and some don't speak English at all. However, most Canadian clinics only have access to English WRT lists and employ English-speaking hearing professionals. Performing English WRT on clients that may not be as comfortable with the language produces meaningless results.
If English is not your first language, WRT results are unreliable except in the rare case where an official recorded 50-word list is available in your mother tongue. Keep in mind, though, "live voice" WRT is always a poor substitute, even if the presenter is able to use your first language. Sometimes it's better not to perform a test at all, if it can't be done right, lest it lead to improper conclusions.
Brain Processing or Speech Issues
To varying degrees, some people (with or without hearing loss) may suffer from issues, unrelated to ear function, that may impair their ability to understand speech or to speak clearly. In such cases, low WRT scores may not indicate a problem with hearing at all and should not be interpreted as such. In fact, in some cases, hearing aid amplification may actually worsen speech processing ability.
The WRT is a valuable component of the traditional hearing test when performed in accordance with best practices. However, when performed in a sub-par manner, the WRT results cannot be trusted. In this case, they may be inaccurate, meaningless, and not worthy of interpretation or consideration.
The startling truth is that if this post was used as a checklist to measure the quality of WRT being commonly performed by hearing clinics in today's hearing aid marketplace, many clinics would fail the grade. Data relating to best practice WRT methods has been available for decades yet many hearing clinics stubbornly cling to inferior practices. Consumers beware.
As a informed hearing aid consumer, you need not understand all the low-level details that go into a proper WRT. But, you need to recognize the signs of a inferior test, how it can affect you, and what it says about the quality of your hearing clinic.
My organization, Independent Hearing Clinics of Canada (IHCC), works with quality, independent hearing clinics to encourage industry best practices for hearing care. We continue to raise public awareness of important issues (like the WRT), empowering hearing aid consumers to achieve the best value possible for their hearing solutions.
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Mueller, B. W. (2013). Word Recognition Testing: The Puzzling Disconnect from Best Practic Benjamin W.Y. Hornsby H. Gustav Mueller. Retrieved October 04, 2016, from http://www.audiologyonline.com/articles/word-recognition-testing-puzzling-disconnect-11978