Individuals with normal hearing in one ear and severe hearing loss in the other ear typically show which effect when noise is closer to the ear with hearing loss?

• A. Improved speech understanding when the noise is closer to the ear with hearing loss
• B. Improved localization when the noise source is closer to the ear with normal hearing
• C. Better speech understanding and localization as reverberation time increases
• D. Improved localization when the noise is at 0° azimuth and the source is closer to the ear with hearing loss

Answer: (A)

In asymmetric hearing, the better ear tends to dominate speech understanding in noisy environments. When noise is placed near the ear with severe loss, the head between the ears casts a shadow that reduces the amount of noise reaching the normal-hearing ear. Meanwhile, the speech signal from the front still arrives to both ears, but the better ear now has a clearer input relative to the noise. The brain then relies on the information from the normal ear to understand speech, leading to an improvement in understanding in that noisy setup. Localization and other factors don’t improve in this configuration; unilateral/asymmetric hearing generally makes localization harder, and increasing reverberation time typically degrades speech understanding rather than helping it.