Transducer Variability in Speech-in-Noise Testing: Considerations Related to Stimulus Bandwidth

Clinical audiologists typically assume that headphones and insert phones will produce comparable results when they are used to conduct speech-in-noise or other audiological tests; however, this may not always be the case. Here, we show that there are significant differences in the scores that previous studies have reported for headphone and insert-phone transducers on the Words-in-Noise (WIN) Test, and discuss the possibility that the variations in high-frequency output that are allowable under the speech source specifications of American National Standards Institute S3.6 might be contributing to transducer-dependent differences in performance for the WIN and other tests that are presented through the auxiliary input channels of clinical audiometers.

A literature review was conducted to identify articles that reported WIN Test results for both listeners with normal hearing and with hearing impairment and specified the type of transducer (insert or TDH-50) used for the data collection.

Among the 19 included studies, participants with normal hearing using inserts exhibited systematically worse WIN Test scores compared to those using TDH-50 headphones, while participants with hearing loss showed comparable average scores across transducer types.

The results highlight the importance of considering transducer type when interpreting WIN Test outcomes, particularly when comparing to normative scores obtained from individuals with normal hearing. Although further research is needed to elucidate the underlying mechanisms driving differences in test performance across transducer types, these findings underscore the need for standardized test administration protocols and careful documentation of transducer type when administering speech-in-noise tests for clinical or research applications.