What Is a Speech Test?
Speech audiometry, sometimes called speech discrimination testing, is a specialised test audiologists use to assess how well individuals can understand spoken words. It’s a type of hearing test that goes beyond the basic checks you might be familiar with, focusing specifically on your ability to make out speech under various conditions.
When Do We Use Speech Audiometry?
At Ear Health, while speech audiometry is not a standard part of our free hearing tests, it plays a critical role under certain circumstances. Here’s when and why we might use this tool:
Targeted Assessments: We consider speech audiometry particularly useful if there’s a question about how much benefit a hearing aid might provide, especially for ears that have had long-term, unaided hearing loss. It helps us understand if these ears can still process speech effectively once it’s audible enough through amplification.
Regulatory Requirements: We conduct speech audiometry to meet specific guidelines for ACC (Accident Compensation Corporation) and Veterans Affairs clients. It ensures consistency between spoken word recognition and standard pure tone tests.
How Does Speech Audiometry Benefit You?
For many of our clients, the comprehensive evaluation from our free hearing test provides enough information to begin making decisions about hearing aids and other interventions. We only add speech audiometry when additional details are necessary to make more informed decisions about hearing care.
At Ear Health, we focus on making your path to better hearing simple and effective. Whether you’re taking advantage of our complimentary tests or need a more detailed speech audiometry evaluation, we aim to provide the proper care, personalised to your specific hearing needs.
A Brief Look at Its History and Importance
Speech audiometry is a sophisticated development from the earliest hearing tests, which use beeps or tones to check hearing ability. Speech, our primary means of communication, holds a special place in both speech and hearing. The roots of speech audiometry trace back to the pioneering work at Bell Labs in the 1920s and 1930s. Initially, researchers there focused on enhancing the efficiency of communication systems, laying the groundwork for modern audiometric techniques.
The importance of speech audiometry surged after World War II, driven by the need to address hearing impairments among returning veterans, and this period marked a significant evolution in assessing speech intelligibility and hearing health, making speech audiometry vital for diagnosis and developing educational and therapeutic strategies tailored to those with hearing loss.
How Speech Audiometry Works in Practice
When you go for a speech audiometry test, a skilled audiologist will guide you through listening tasks. These often involve repeating words played through headphones to determine one’s Speech Recognition Threshold (SRT). The New Zealand standard speech test at Ear Health first finds the loudness where the score is a maximum (often 100%). It then seeks to find the loudness where the score is half the maximum (usually 50%).
Why is Speech Audiometry Important?
Speech audiometry primarily aims to measure speech stimulus thresholds and evaluate communication difficulty. It also serves as a validation for pure-tone audiometry.
Speech audiometry helps to determine the likely benefit from amplification using hearing aids. If the SRT is much higher than expected, this means that even when one can hear speech sounds, one cannot use the sound to understand speech.
Accurate speech audiometry assessments are crucial because they inform decisions regarding an individual’s rehabilitation, educational needs, and occupational recommendations. These assessments directly influence a broad spectrum of outcomes for the tested person, including social, psychological, medical, and legal consequences.
Types of Speech Audiometry Tests
Audiologists and hearing loss researchers globally employ a variety of speech audiometry tests.
In New Zealand, government agencies such as the Accident Compensation Corporation (ACC) and Veterans Affairs require Speech Recognition Testing using CVC/A-B Wordlists for diagnostic hearing assessments.
The New Zealand Audiological Society has laid out some guidelines for conducting audiological investigations in their Best Practice Guidelines (BPGs) series. The BPGs provide a standard protocol for administering speech audiometry throughout New Zealand that aligns with evidence-based practices and international consensus on best practices. These guidelines ensure that the process is standardised and reflects the latest developments in the field.
1. Speech Detection Threshold (SDT)
The Speech Detection Threshold (SDT) test measures the quietest level at which you can detect the presence of speech, akin to discerning a whisper. During this test, your audiologist will instruct you to signal—perhaps by pressing a button or raising a hand—the moment you first hear a sound without needing to identify specific words.
The test begins at 10 dB below your best pure-tone air conduction (AC) threshold. A single word is presented at each level, with the intensity increasing in 5 dB steps until you can hear the word. If you indicate hearing a word, the level is reduced by 10 dB and then gradually increased in 5 dB steps to pinpoint the precise threshold level. The SDT is determined at the level where you consistently detect words on two out of three ascending trials.
This approach is beneficial as an initial check of your hearing, ensuring consistency with other standard hearing tests like pure-tone audiometry. Establishing a reliable SDT helps confirm that your hearing thresholds align well across different types of auditory assessments.
2. Speech Recognition Testing Using CVC/A-B Wordlists
This test combines listening at loud and quiet levels and evaluates how clearly you can identify and repeat words. You will listen to CVC (Consonant-Vowel-Consonant) word lists through headphones during the test. These lists are phonemically balanced to ensure that each word accurately represents typical speech patterns. Each word consists of three phonemes: two consonants surrounding a central vowel. For example, words like “cat,” “dog,” and “bus” are part of the CVC list. Your audiologist will prompt you to repeat the words after hearing them.
Your responses are scored based on the precision of your phoneme reproduction. Scoring is thorough: an entirely correct word earns you full points, and you will receive partial points if you correctly repeat one or two phonemes. For instance, if the word “cat” is spoken and you respond with “cap,” you would receive partial points for correctly repeating the initial consonant and the vowel but not the final consonant. If you respond with “cat,” you earn the full score. If you only correctly identify the initial sound, such as just “c,” you would receive a lower partial score.
The testing begins by setting the audio above your 2000Hz threshold, adjusted according to your hearing capacity. The goal is to determine your Performance-Intensity (PI) function, which helps find the optimal speech level where you perform best, known as the Performance Intensity Maximum (PI Max). Additionally, the test identifies your Half-Peak Level (HPL), the volume at which your phoneme recognition drops to half of the PI Max score.
3. Speech Recognition Threshold (SRT)
Speech Recognition Threshold (SRT) testing evaluates the softest level at which you can understand and correctly repeat 50% of spoken words. This threshold is crucial as it assesses your ability to discern speech rather than just detecting sound. The test uses spondaic words with two syllables of equal stress, which are ideal because of their clear and distinct pronunciation.
The procedure for determining the SRT involves initially setting the sound level of the spondees (the test words) at 30 dB HL. Suppose you do not respond correctly at this level. In that case, the intensity is increased in steps—first to 50 dB HL and then by 10 dB increments up to 70 dB HL, followed by 5 dB increments, until a correct response is elicited or until the upper limit of comfortable loudness (ULCL) is reached. Once a correct response is achieved, the intensity is adjusted down by 10 dB until no response occurs and then fine-tuned by alternating between reducing by 10 dB and increasing by 5 dB at each step until you can correctly identify three spondees at a specific level.
This method establishes your ability to understand speech at minimal levels. It helps to compare this ability with your pure tone audiometry results, providing a comprehensive understanding of your hearing capabilities.
Preparing for a Speech Audiometry Test
Getting Ready for Your Test
Here’s what to expect and how to prepare to ensure accurate results. The process is quick, typically lasting about 10-15 minutes, but the insights gained are valuable for understanding your hearing health.
Before the Test
Health Check-Up: Your test typically begins with a brief evaluation of your ears using an otoscope, which allows your audiologist to identify potential issues, such as earwax blockages, a perforated eardrum, or an ear infection, that could affect the accuracy of the test.
Medical History: You might also complete a questionnaire about your health history, previous exposure to loud noises, and current symptoms.
During the Test
In the Sound Booth: You’ll sit in a specially designed soundproof booth for the test. This quiet, controlled environment helps ensure that only the sounds played during the test are what you hear.
Wearing Headphones: You’ll hear words played at different volumes. It’s like listening to a low-volume podcast that gradually gets louder.
Repeating Words: You’ll be asked to repeat words to find out the softest speech level at which you can recognise half the sounds in words, known as your Speech Recognition Threshold (SRT).
Ensuring Accurate Results
Your audiologist will perform the test in a room with minimal background noise—no louder than a whisper—or ideally in an audiology booth to ensure that nothing interferes with your hearing during the test.
What to Remember
Just relax and focus on the words. The audiologist is there to guide you through the process and help you with any difficulties. This test is a step toward better understanding and improving your hearing, which can significantly improve your quality of life.
Limitations of Speech Testing
Speech audiometry tests are valuable tools for assessing hearing capabilities and understanding speech discrimination abilities in various environments. However, these tests have limitations, particularly when evaluating individuals with specific needs or backgrounds. Understanding these limitations can help clients and clinicians manage expectations and adapt testing strategies accordingly.
Challenges for Specific Populations
Profound Hearing Loss: Individuals with profound hearing loss may not benefit from standard speech audiometry tests that use typical speech stimuli at normal conversational levels. These tests might not be sensitive enough to detect the limited hearing capabilities in such cases, necessitating alternative methods.
Nonverbal Individuals: Traditional speech audiometry, which requires repeating words or sentences to the examiner, is not feasible for nonverbal people.
Non-English Speaking Background: Speech audiometry typically uses stimuli in the dominant language of the testing environment, often English. For speakers of other languages, these English tests may not accurately reflect true speech discrimination abilities.
While speech audiometry is a powerful diagnostic tool, it is not one-size-fits-all. Recognising its limitations and the need for flexible testing approaches is crucial in providing accurate and meaningful hearing assessments. This adaptability ensures that all individuals, regardless of their hearing level, communication abilities, or language background, receive the most effective and appropriate evaluation for their needs.
Final Thoughts
Understanding the nuances of speech audiometry plays a crucial role in providing targeted and effective hearing solutions, especially for those who face complex auditory challenges or have specific regulatory needs. While not everyone will require speech audiometry as part of their hearing assessment, this tool becomes indispensable under particular conditions.
Speech audiometry is a sophisticated extension of hearing tests that focuses on your ability to understand speech in various auditory settings. It assesses the ability to hear sounds and to process and understand speech effectively. These tests are vital for clients with long-standing unaided hearing loss or those needing to meet specific regulatory criteria.
This specialised testing method, which includes tests such as the Speech Detection Threshold (SDT), Speech Recognition Threshold (SRT), and Word Recognition Score (WRS), allows audiologists to tailor interventions under specific circumstances.
Our commitment at Ear Health is to offer a straightforward, accessible path to better hearing. Whether through our comprehensive free hearing tests or the more detailed speech audiometry evaluations when required, our goal is to provide each client with the most effective hearing solutions tailored to their unique needs.
