The importance of accurate hearing assessment cannot be overstated, given its significant impact on the quality of life for individuals with hearing loss. Typically, audiological evaluations involve a standard test battery that includes air conduction (AC), bone conduction (BC), speech reception threshold (SRT), and word recognition scores (WRS). However, the clinical utility of these tests varies, raising questions about the necessity of including all of them in every assessment. This blog explores the functional utility of BC, SRT, and WRS measurements and provides recommendations for optimizing audiological test batteries.
Understanding the Standard Audiological Test Battery
Pure-tone audiometry, which includes AC and BC thresholds, is the cornerstone of hearing assessment. AC thresholds measure the softest audible signals through the external, middle, and inner ears, while BC thresholds stimulate the inner ear directly through skull vibrations. The difference between AC and BC thresholds, known as the air-bone gap (ABG), helps determine the type of hearing loss—conductive, sensorineural, or mixed.
Speech audiometry complements pure-tone audiometry by assessing speech perception. SRT represents the lowest sound level at which 50% of the stimuli are recognized, while WRS measures the percentage of correctly repeated words at a suprathreshold level. These tests provide critical information about an individual's ability to understand speech, aiding in the diagnosis and management of hearing loss.
Evaluating the Clinical Utility of BC, SRT, and WRS
In a study involving 134 patients, we compared pure-tone audiometry and speech audiometry findings with objective tests such as tympanometry, acoustic reflex threshold (ART), and distortion product otoacoustic emissions (DPOAEs). The results showed that the values of DPOAEs were abnormal among a significant number of people diagnosed with normal hearing according to pure-tone audiometry. Additionally, the correlations between the degree of hearing loss and the SRT and WRS were moderate and low, respectively.
Notably, an ABG greater than 10 dB was present in approximately 25% of patients with normal tympanogram, ART, and DPOAE findings. These results suggest that BC, SRT, and WRS may add limited diagnostic value in several cases.
Recommendations for Optimizing Audiological Test Batteries
Based on our findings, we recommend a more case-specific approach to audiological assessments. Here are some guidelines:
- Omit BC Tests: For patients with no history of ear disorders and normal findings on tympanometry, ART, and DPOAEs, BC tests may not be necessary.
- Selective Use of SRT: SRT may not be needed for patients with normal DPOAEs or those with bilateral sloping hearing loss (age < 65 years).
- Limit WRS Testing: WRS in quiet at one presentation level may not add significant value for most patients.
Conclusion
Our study suggests that rather than adhering to a fixed set of tests, audiologists should consider the specific needs of each patient to optimize the audiological test battery. By selectively including tests that add diagnostic value, clinicians can enhance the efficiency and effectiveness of hearing assessments, ultimately improving patient outcomes.
