Swedish researchers have published a small study analyzing speech recognition in noise using bilateral open-fit hearing aids. They concluded that there is a limited benefit of directional microphones and noise reduction.

The study’s objective was to investigate speech recognition performance in noise with bilateral open-fit hearing aids, and, as a reference, also with closed earmolds in omnidirectional mode, directional mode, and directional mode in conjunction with noise reduction.

The research involved 20 adults, men and women, who had no prior experience with hearing aids. All had symmetric sensorineural mild hearing loss in the lower frequencies and moderate to severe hearing loss in the higher frequencies. Each patient was fitted bilaterally with open-fitting hearing aids programmed to “first fit” with thin tubes or open domes, and fitted. Their average age was around 57 years old.

The scientists found that speech recognition performance in noise was not significantly better with an omnidirectional microphone compared to unaided, whereas performance was significantly better with a directional microphone compared to unaided.

With open fitting, no significant additional advantage was obtained by combining the directional microphone with a noise reduction algorithm, but with closed earmolds, a significant additional advantage of 0.8 dB was obtained.

The researchers, Magnusson et al, concluded, “The significant, though limited, advantage of directional microphones and the absence of additional significant improvement by a noise reduction algorithm should be considered when fitting open-fit hearing aids.”

SOURCE: International Journal of Audiology abstract