Children's speech perception and loudness ratings when fitted with hearing AIDS using the DSL v.4.1 and the NAL-NL1 prescriptions

This paper reports speech and loudness measures on a group of children in a double-blind cross-over trial comparing the NAL-NL1 and DSL[i/o] prescriptions. Twenty-four children with hearing impairment were fitted with digital WDRC hearing aids at each site (Australia, Canada). Speech recognition was measured for nonsense syllables and for the 50% correct threshold for sentence recognition in noise. Loudness ratings for sentences were made on a 7-point scale. Measures were made at fitting and repeated following 8-week trials. Fitting orders were randomized and counterbalanced. Significant differences in consonant recognition occurred for individual children. On average, scores at the 80 dB SPL presentation level were better with the NAL-NL1 fitting. Loudness ratings differed at baseline but did not differ following home trials. Speech recognition scores revealed a small but significant interaction of prescription with level in quiet but not in noise. Individual children had significant performance differences. Loudness ratings showed significant acclimatization effects for children at both sites.