Recorded Speech Tests vs. Monitored Live Voice
Of the many hearing tests, speech audiometry is one of the most fundamental in the test battery. Unfortunately, it has been shown to be one of the tests that audiologists conduct without using procedures that have been shown to be valid and reliable (Martin & Pennington, 1971; Martin & Forbis, 1978; Martin & Sides, 1985; Martin & Morris, 1989; Martin et al, 1994, 1998; Wiley et al,1995).
The continued use of monitored live voice (MLV) for speech stimuli presentation is prevalent, despite ample literature indicating why recorded speech should be preferred. (Carhart, 1946, 1965; Brandy, 1966; Kreul et al, 1969; Penrod, 1979; Hood & Poole, 1980; Mullennix et al, 1989; Roeser & Clark, 2008; Wilson & McArdle, 2008; Katz, 2014).
Recorded speech is a more accurate method of performing speech audiometry. Standardization of speech audiology test material is important for test and result reliability. The use of recorded speech stimuli as a standard of practice has been validated by many authors. (Mendel & Danhauer, 1997; Roeser & Clark, 2008).
Speech audiology tests assess auditory function by using speech stimuli (words). Speech stimuli are more representative of daily listening than pure tones. Speech tests gives clinicians a clearer picture of a patient’s functional hearing ability and is crucial in predicting hearing aid outcome/success.
Hearing and speech understanding are of significant importance in our lives. For children, testing speech intelligibility, which is their ability to hear and understand speech, is fundamental for oral language learning and development. For adults, difficulty in hearing and understanding speech limits their ability to participate in daily communication interactions.
Method of presentation: Pros and Cons
In Monitored Live Voice testing (MLV) clinicians present speech material through a microphone. The microphone is connected to a VU (Volume Unit) meter which monitors the voice intensity level.
The advantages of MLV testing is that it is easy to administer and allows flexibility of the test procedure. Furthermore, the average presentation time of MLV is shorter.
The disadvantages, however, outweigh the advantages.
MLV lacks precise control over the administrators voice intensity. Different testers voice frequencies and pronunciations can yield large differences in results even if the same test materials are used and the same patient is tested.
Clinicians can’t serve patients with different languages to their own unless they are fluent in patient’s native tongue. Vocal fatigue can also increase the probability of variations in tones, accents and speaker error, resulting in inaccurate speech test results.
Enter the recorded speech test.
Here, speech materials are recorded in an acoustically controlled environment, professionally mastered, and presented via a CD-player or PC that is connected to the audiometer.
The advantages of recorded material include greater control of signal intensity and test-retest reliability of the materials. Recorded materials improve both the intrasubject and intersubject precision of threshold and suprathreshold measures by providing a consistent level for all test items and consistent speech patterns between patients.
Some disadvantages include the lack of flexibility in terms of timing between presentation of words and easy repetition of words. Cost and effort required to produce high quality clinical material. While, validated recorded word-lists are available in some languages the list is by no means extensive.
The verdict is out.
While most clinicians and researchers agree and advocate for the use of recorded speech for audiometric testing, many practices are still not following this generally accepted and validated premise.
Nonetheless, to reduce the administrator/s voice variability, possibility of microphone misplacement, requirement for calibration of speakers, and articulation inaccuracies and errors, the recommended standard of practice is to use recorded speech stimuli.
In the pursuit of accuracy, it is clear that the clinical benefits of recorded materials far outweigh that of monitored live voice. Looking at the evolution and advancement of medical technology, it is shocking that most traditional audiometers are still not able to offer recorded speech materials.
KUDUwave™ – integrated Recorded Speech Materials
The KUDUwave™ has revolutionized recorded speech testing. It has an already extensive and growing pool of integrated speech materials(word lists) and flexible options.
The KUDUwave™ employs evidence based practices that ensure accurate and reliable assessment and diagnostic data which facilitates accurate and appropriate management of auditory disorders.
Standardized speech material
The biggest challenge with MLV testing is the lack of uniformity in test presentation compared to recorded speech. The recorded word-lists offered in the KUDUwave™ are calibrated to peak the VU meter appropriately each time, no matter how many speech audiometry tests you do in a day.
So long, vocal fatigue.
Speech testing starts quickly and there is no need for biological calibration of the VU meter before testing.
Ciao ciao, VU meter.
Flexible speech testing
The presentation of speech materials is controlled via software (KUDUwave 5™). This allows the clinicians to present the words in their own time and enjoy similar flexibility found in MLV, such as repeating a word. Clinicians can use recorded stimuli to obtain accurate and reliable speech recognition threshold results while; making notes during testing and real-time test scoring.
Goodbye, finger-counting the words. (You know you have done it too)
The clinician can also use their choice of evidence-based protocol to conduct the tests.
Multilingual speech testing
Even when a patient claims to have a moderate to advanced ability in a language like English, bilingual speakers whose first language is not English are found to score lower on English word recognition tests than native English speakers who have superior language familiarity. (Takayanagi, Dirks and Moshfegh, 2002).
This lower score has been demonstrated by both hearing impaired and normal hearing individuals. Therefore, the non-native listeners’ inability to recognize words cannot be attributed to their auditory function alone, but the lack of familiarity of the English words.
A recommended speech audiometry test procedure is familiarization of the word list (ASHA 1988; Katz, 2014). Patients should become familiar with the word list prior to the test. The patient should be able to repeat back the words as a demonstration of word recognition.
If a patient is not able to repeat back the word presented, Katz (2014) recommends the word be removed from the test list.
In essence, testing an individual with speech materials that are not of their native language (or not familiar to them) may affect the reliability of the results.
The KUDUwave™ helps to remove language barriers, and incorrect results by its ability to store and use multiple, validated, recorded speech materials in various languages and dialects across the world. From isiXhosa to French.
Here is an idea.
Isn’t it about time sound engineering, linguistics, audiology and speech therapy departments around the world got together and produced speech material for all languages?
I think Yes!
This is how simple it could be.
The KUDUwave™ displays each word on the screen, clinicians can see the words as they are presented and scored eliminating patients lip-reading.
Sayōnara, hiding behind a piece of paper so the patient can’t see your lips move.
Integrated word lists means that you no longer have to search for that word list you are sure you used to have and its corresponding CD. No more CDs or CD player cluttering up your surface. After all, I am convinced that audiology may be the only profession keeping the CD player industry in business.
Adios, desktop clutter.
Auf Wiedersehen, wasted time.
Now, imagine just jumping onto your PC to start testing, with a fully loaded list of speech material at your fingertips and within a few mouse clicks you are on your way.
Hamba kahle, stress and strain.
Recorded speech used to be slow and rigid. The KUDUwave™ makes it quick and easy. It even saves the tests digitally. What more could you ask for?
It’s time to say Au revoir to old school and Hello, Bonjour, and Hola to KUDUwave™.