Purpose: To investigate the clinical efficacy of linear frequency transposition (LFT) for
a group of school-age children.
Research Design: A nonrandomized, within-subject design was implemented to investigate vowel and consonant
recognition and fricative articulation of school-age children utilizing this feature.
Study Sample: 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.
Data Collection and Analysis: 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: 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.
Conclusions: These results suggest that LFT is a potentially useful hearing aid feature for school-age
children with a precipitous HF sensorineural hearing loss.
Key Words
Frequency transposition - hearing aids - speech recognition
