Speech audiometry is a specialized component of a full hearing evaluation that determines how well a person hears and understands spoken language. This testing goes beyond simply measuring the quietest sounds a person can detect and focuses on the ability to recognize and process the complex signals of speech. Audiologists use standardized tests to determine a patient’s speech hearing abilities under various listening conditions, including both quiet and noisy environments. The results offer a functional assessment of how hearing impairment impacts daily communication, which is invaluable for diagnosis and treatment planning. This method is a foundational tool in audiology.
The Unique Role of Speech Testing
Speech audiometry is necessary because it measures the clarity and comprehension of speech, a capability that pure-tone testing cannot capture. Pure-tone audiometry, often called the “beep test,” only measures a patient’s hearing sensitivity—the softest level at which they can hear single, isolated tones at different pitches. This measurement provides a threshold for sound detection but offers limited insight into how the brain processes complex speech sounds. Speech understanding is a complex cognitive process that requires the auditory system to receive the sound, and the brain to recognize and interpret the words.
Two people can have nearly identical results on a pure-tone test but have very different abilities to understand conversation. A standard hearing test might show that a person can hear sound at a certain volume, but speech testing reveals if they can distinguish between the words “cat” and “hat” at that volume. This distinction is significant because many individuals with hearing loss report that they can hear people talking but struggle to understand the words being said. Speech testing simulates real-world listening and provides a functional measure of a patient’s communication ability.
Standard Assessments Used
A comprehensive speech audiometry evaluation typically involves three distinct tests, each focusing on a different aspect of speech perception.
Speech Recognition Threshold (SRT)
The SRT identifies the softest volume level at which a person can correctly repeat 50% of the speech material presented. This test uses familiar two-syllable words, known as spondees, such as “baseball” or “hotdog.” The patient repeats the words as the volume is progressively lowered until they can only recognize about half of them, providing a reference point for their hearing sensitivity to speech.
Word Recognition Score (WRS)
The WRS, sometimes called the Speech Discrimination Score, measures speech clarity. This test presents a standardized list of single-syllable words at a comfortable listening level. The presentation volume is intentionally set well above the patient’s hearing threshold, typically 30 to 40 decibels higher than the SRT, to ensure the words are clearly audible. The resulting score is a percentage of words the patient correctly repeats, which reflects the inner ear and auditory nerve’s ability to process speech sounds accurately.
Speech in Noise (SIN) Testing
SIN testing evaluates the ability to understand speech when background noise is present. This test simulates real-world situations, like a conversation in a busy restaurant, by playing speech stimuli alongside competing background noise, such as multi-talker babble. The patient is asked to repeat the target words or sentences while the noise level changes. The result is a measure of the Signal-to-Noise Ratio (SNR) loss, which indicates how much louder the speech needs to be compared to the noise for the patient to understand a certain percentage of the words.
How Speech Audiometry Results Are Used
The data collected from speech audiometry tests is used for diagnosing the type and severity of hearing loss and for planning effective treatment. The SRT is used as a cross-check to verify the reliability of the pure-tone test results; a significant mismatch between the two may suggest an issue that requires further investigation. When the WRS is unexpectedly poor compared to the pure-tone thresholds, it can indicate a problem beyond the cochlea, such as auditory nerve or central processing issues. For example, a high-frequency hearing loss due to aging might still yield a relatively good WRS, while a retro-cochlear pathology could cause a disproportionately low WRS.
The WRS is particularly valuable for determining the potential benefit a patient can expect from hearing aids. A high WRS suggests that once sound is amplified to an audible level, the patient’s auditory system is still capable of recognizing most words correctly. Conversely, a very low WRS indicates that even with proper amplification, the clarity of the speech signal remains poor, setting realistic expectations for the patient and clinician.
The SIN test results guide the specific features and technology recommended in a hearing aid, such as advanced noise reduction settings. A significant SNR loss suggests the patient will struggle greatly in noisy environments, influencing the choice of hearing aid and the counseling provided regarding its performance. These combined speech scores help audiologists determine the appropriate gain and maximum output settings for amplification devices, ensuring the treatment is tailored to the patient’s functional communication needs.