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Effects of Degree and Configuration of Hearing Loss on the Contribution of High- and Low-Frequency Speech Information to Bilateral Speech Understanding

Hornsby, Benjamin W. Y.1; Johnson, Earl E.2,3; Picou, Erin1

doi: 10.1097/AUD.0b013e31820e5028
Research Articles

Objectives: The purpose of this study was to examine the effects of degree and configuration of hearing loss on the use of, and benefit from, information in amplified high- and low-frequency speech presented in background noise.

Design: Sixty-two adults with a wide range of high- and low-frequency sensorineural hearing loss (5 to 115+ dB HL) participated in the study. To examine the contribution of speech information in different frequency regions, speech understanding in noise was assessed in multiple low- and high-pass filter conditions, as well as a band-pass (713 to 3534 Hz) and wideband (143 to 8976 Hz) condition. To increase audibility over a wide frequency range, speech and noise were amplified based on each individual's hearing loss. A stepwise multiple linear regression approach was used to examine the contribution of several factors to (1) absolute performance in each filter condition and (2) the change in performance with the addition of amplified high- and low-frequency speech components.

Results: Results from the regression analysis showed that degree of hearing loss was the strongest predictor of absolute performance for low- and high-pass filtered speech materials. In addition, configuration of hearing loss affected both absolute performance for severely low-pass filtered speech and benefit from extending high-frequency (3534 to 8976 Hz) bandwidth. Specifically, individuals with steeply sloping high-frequency losses made better use of low-pass filtered speech information than individuals with similar low-frequency thresholds but less high-frequency loss. In contrast, given similar high-frequency thresholds, individuals with flat hearing losses received more benefit from extending high-frequency bandwidth than individuals with more sloping losses.

Conclusions: Consistent with previous work, benefit from speech information in a given frequency region generally decreases as degree of hearing loss in that frequency region increases. However, given a similar degree of loss, the configuration of hearing loss also affects the ability to use speech information in different frequency regions. Except for individuals with steeply sloping high-frequency losses, providing high-frequency amplification (3534 to 8976 Hz) had either a beneficial effect on, or did not significantly degrade, speech understanding. These findings highlight the importance of extended high-frequency amplification for listeners with a wide range of high-frequency hearing losses, when seeking to maximize intelligibility.

The purpose of this study was to examine the effects of degree and configuration of hearing loss on the use of, and benefit from, amplified high- and low-frequency speech presented in background noise. A stepwise multiple linear regression approach was used to examine the contribution of various factors to (1) absolute performance in various filter conditions and (2) the change in performance with the addition of high- and low-frequency speech information. Results revealed that both degree and configuration of hearing loss affected absolute performance and benefit from speech information in different frequency regions.

1Department of Hearing and Speech Science, Dan Maddox Hearing Aid Research Laboratory, Vanderbilt University, Vanderbilt Bill Wilkerson Center, Nashville, Tennessee; 2U.S. Department of Veterans Affairs; and 3Department of Communicative Disorders, East Tennessee State University, Mountain Home, Tennessee.

This work was supported, in part, by Grant R03 DC006576 from the National Institute on Deafness and Other Communication Disorders (National Institutes of Health) and the Dan Maddox Hearing Aid Research Foundation.

Address for correspondence: Benjamin W. Y. Hornsby, Vanderbilt Bill Wilkerson Center, Room 8310 Medical Center East, South Tower, 1215 21st Ave. South, Nashville, TN 37232, USA. E-mail: ben.hornsby@vanderbilt.edu.

Received August 27, 2009; accepted December 23, 2010.

© 2011 Lippincott Williams & Wilkins, Inc.