Judgement of disproportionate loss between Mandarin monosyllable discrimination and pure tone hearing thresholds

Objective To establish the criteria of the disproportionate loss of Mandarin monosyllable discriminative abilities to pure tone hearing thresholds. Methods Total of 165 patients with varying degrees of sensorineural hearing loss were recruited for routine audiological evaluations. The speech discrimination scores were obtained by Mandarin phonemic-balanced monosyllable lists via self-made speech audiometric software. The Performance-Intensity（P-I） function for individual ear was obtained by the same list which was administrated in ascending intensities, with 25 monosyllables presenting randomly. The lowest intensity was determined by the lowest pure tone threshold among all audiometric frequencies minus 5 dB.The intensities were increased in 5 dB step until the score was 100% or the intensity was reached to the patient's uncomfortable level The PBmax was obtained from the P-I plot. Three parameters about pure tone average hearing thresholds, including PTA1 （average of 0. 5, 1 and 2 kHz）, PTA2 （average of 1, 2 and 4 kHz） and PTA3 （average of 0. 5, 1, 2 and 4 kHz）, as well as three parameters about audiogram slope,including Slope0. 5 （4 kHz minus 0. 5 kHz）, Slope1 （4 kHz minus 1 kHz） and Slope2 （4 kHz minus 2 kHz）,were calculated respectively. The correlations between PBmax and above parameters were analyzed by SPSS10. 0 statistical software. Results The audiogram slopes were not shown any correlation with PBmax,while the pure tone average thresholds, especially PTA3 （r = - 0. 595, P = 0. 000 ） were confirmed to correlate with PBmax. In the scatter plot based on PBmax and PTA3, a linear boundary was constructed encompassing approximately 99% of observed data collected from the sensorineural hearing-impaired.Conclusion Any PBmax score falling below the boundary should be considered with high possibility and disproportionately poor comparision with pure tone hearing thresholds. Key words: Hearing loss, sensorineural; Audiometry, speech; Monosyllable, Mandarin; Audiometry, pure-tone