Comparison of hearing aids and assistive listening devices with omni-directional and directional microphones at personal communication distances

This study was conducted to compare performance between binaural hearing aids and an ALD used in two modes (companion mode and interview mode). Performance was evaluated on the basis of word recognition at two distances and SMI at four distances. Additionally, this study was conducted to determine if directional microphones can be used to significantly improve performance with both hearing aids and an ALD using measures of word recognition and SNR. Word recognition performance measures indicated a rank ordering of the amplification devices with the poorest performance with the HA, improving with the ALDI and best when using the ALDC. The use of directional microphones improved word recognition for each device but the improvement was not sufficient to change the rank ordering of devices. As communication distance increased, the SMR decreased for three amplification devices. The measures of SNR found the least favorable SNR to be with the HA improving with the ALDI and best with the ALDC. The use of directional microphones increased the SNR for the amplification devices over use of omni-directional microphones, however, the rank ordering did not change. Additionally, a critical SNR was established for the listeners in this study. Improving the SNR above the level of the SNR did not significantly improve word recognition performance regardless of amplification device or communication distance. These results provide clear evidence that the ALD can improve both word recognition performance and SNR more than HAs. While the use of directional microphones can be beneficial, the benefit of directional microphones in HA does not out-perform the benefit of directional microphones in ALD. Additionally, the results indicate that the ALD can be used effectively in the interview mode at personal communication distances.