The effects of various front-to-back ratios on the performance of directional microphone hearing aids.

Twenty-four sensorineural hearing-impaired adults were evaluated using four directional microphone hearing aids differing only in front-to-back ratios. The speech material utilized was the Synthetic Sentence Identification Message Competition Ratios of 0, -10, and -20 dB. The primary signal was presented from a 0 degree azimuth with the competing message was presented from a direct overhead location. The results revealed a systematic improvement in speech understanding as the size of the front-to-back ratio increased. This relationship was not significantly affected by the difficulty of the listening situation.