Comparison of the Ling-6 Sound Test with Warble Tone Stimuli in Audiometry of Hearing-Impaired Children Using Hearing Aids Considering Different Prescriptions and Normal-Hearing Children

Background and Aim: Speech is a vital stimulus and the ultimate goal of hearing aid fitting to make the speech an audible signal. The purpose of this research was to investigate whether it is possible to track the threshold with speech phonemes and which of the two fitting methods of Desired Sensation Level version 5.0 (DSL v5.0) and National Acoustic Laboratories-Nonlinear 2 (NAL-NL2) provide better audibility for the phonemes. Methods: In this cross-sectional study, the unaided thresholds of 18 normal-hearing children and the aided thresholds of 15 hearing-impaired children aged 5-8 years were evaluated with two types of stimuli. DSL v5.0 and NAL-NL2 methods were used for hearing aid fitting in hearing-impaired children. Results: There was a significant relationship between the unaided and aided thresholds   of each phoneme and the warble tone threshold at the corresponding frequency (p<0.01), except for the phoneme /s/. The results showed a significant difference between the aided thresholds of each phoneme and the upper limit of the speech banana in the corresponding frequency for each method (Z=–4.99, p≤0.001). Conclusion: The results showed that phonemes could be used to assess unaided and aided thresholds. In the first fit, both methods estimated the amount of amplification that caused the average aided thresholds for these six phonemes for moderate to severe hearing loss to be positioned within the speech banana range, except for the average aided thresholds for the /s/ phoneme in the NAL-NL2 method that was placed outside the range. Keywords: Ling-6 sound test; pediatric audiometry; desired sensation level version 5.0; national acoustic laboratories-nonlinear 2