Effect of linear frequency transposition on speech recognition and production of school-age children

To investigate the clinical efficacy of linear frequency transposition (LFT) for a group of school-age children.

A nonrandomized, within-subject design was implemented to investigate vowel and consonant recognition and fricative articulation of school-age children utilizing this feature.

Ten children, aged 6 years and 3 months, to 13 years and 6 months from a special education school district participated in this study. Individual hearing thresholds ranged from normal to moderate in the low frequencies and from severe to profound in the high frequencies. Average language age of children was within 2.2 years of chronological age.

Phoneme recognition and fricative articulation performance were compared for three conditions: (1) with the children's own hearing aids, (2) with an advanced hearing instrument utilizing LFT, and (3) with the same instrument without LFT. Nonsense syllable materials were administered at 30 and 50 dB HL input levels. Fricative articulation was measured by analyzing speech samples of conversational speech and oral reading passages. Repeated measures general linear model was utilized to determine the significance of any noted effects.

Results indicated significant improvements in vowel and consonant recognition with LFT for the 30 dB HL input level. Significant improvement in the accuracy of production of high-frequency (HF) fricatives after six weeks of use of LFT was also observed.

These results suggest that LFT is a potentially useful hearing aid feature for school-age children with a precipitous HF sensorineural hearing loss.