About 1 in 6 people (16.7% of listeners) present with binaural interference—the condition of poorer speech recognition when listening with two ears versus one ear—according to new research published in the January 2017 Journal of the American Academy of Audiology by Bruna Mussoi, PhD, AuD, and Ruth Bentler, PhD, of the University of Iowa in Iowa City. Although the new information should not dissuade hearing care professionals from recommending binaural hearing aid fittings, it does call attention to the need for being mindful that some people may have a real and logical preference for using only one hearing aid.
Mussoi and Bentler examined binaural interference in three groups that totaled 33 people: younger adults with normal hearing, older adults with normal hearing, and older adults with symmetrical hearing loss. Participants did not use hearing aids during any of the testing. Right and left ears were tested individually and binaurally using the Hearing in Noise Test (HINT) and Connected Speech Test (CST) in sound-field with speech presented in front of the listener and noise directly behind them. The study also involved the Dichotic Digits Test (DDT), in which participants listen binaurally (signals are presented at the same time to both ears) through headphones.
In the HINT and CST, the study results were somewhat contradictory. With the CST, all groups showed binaural advantage, and 12% experienced binaural advantage in the two speech-in-babble ratios (SBR) tested, while one participant had binaural interference at each of the two SBRs. The HINT revealed no effect in terms of monaural versus binaural listening over all groups; however, the older hearing-impaired group had significantly poorer results across all three conditions (right, left, binaural), and within-subject analysis showed that 27% of these participants had binaural interference, while 18% experience binaural advantage. Also with the HINT, when pooling the two elderly groups, 33.3% of participants in the two elderly groups exhibited binaural interference, compared with about half that percentage (16.7%) for the younger group. The DDT showed a significant right-ear advantage for the entire group and for at least some subjects when inspecting individual data.
Overall, the authors state that the results support the occurrence of binaural interference in 16.7% of listeners, and hearing loss did not seem to influence the probability of a person exhibiting binaural interference. The findings did suggest that older adults may be more likely to have binaural interference, but more research is needed on the topic. Mussoi and Bentler conclude:
“The possibility of binaural interference need not change the general practice of binaural hearing aid fittings for listeners with symmetric hearing loss. However, it is imperative that clinicians be aware of binaural interference and be attentive to its signs, such as subjective reports of preference for one hearing aid.” They suggest that bilateral speech-in-noise testing with adaptive levels of background noise (eg, HINT) can lend insights into confirming a patient’s testimony relative to a preference for monaural hearing aid use. —KES
Study citation: Mussoi BS, Bentler RA. Binaural interference and the effects of age and hearing loss. J Am Acad Audiol. 2017;28(1)[Jan]:5-13. doi: 10.3766/jaaa.15011.