Edge frequency effect on speech recognition in patients with steep-slope hearing loss

Abstract

AimThe aim of this study was to evaluate the effect of edge frequency on speech recognition after nonlinear frequency compression (NFC) using Arabic consonant speech discrimination lists.Patients and methodsThe study was conducted on 20 adult literate patients with bilateral steep-slope high-frequency sensory–neural hearing loss. Patients were subjected to history taking, ear examination, puretone audiometry, and threshold equalizing noise (HL) test to estimate cochlear dead regions. They were divided into four groups according to the edge frequency. Speech recognition was evaluated using modified Arabic consonant discrimination lists before and after amplification with NFC at three settings that differed in cutoff frequency of compression using the same hearing aid. Free field aided thresholds were obtained in every setting.ResultsPatients showed improvement in aided thresholds when the cutoff frequency was lowered. Speech recognition evaluation showed that the extent of dead regions has a marked impact on patients’ speech recognition score. Patients with the lowest edge frequencyobtainedtheworstspeechrecognitionscoreandleastbenefitfromlowering the cutoff frequency, unlike those patients with the highest edge frequency who had better speech recognition and benefitted more from the highest cutoff frequency.ConclusionIdentifying edge frequency in NFC is important, especially in those patients with steep-slope configuration, as the lower the edge frequency, the poorer the performance. In contrast, satisfactory amplification is reached when the cutoff frequency is at or near the edge frequency.