A Study Of Masking Level Difference And Speech In Noise Test In Hearing Impaired Youths And Seniors

Objective To observe the difference of masking level difference(MLD)in normal hearing and mild hearing loss crowd,and analyze whether the MLD test frequency,type of hearing loss,age and gender will affect the result.And observe the relationship between MLD and speech in noise test threshold’s signal to noise ratio(SNR),to investigate the clinical value of MLD test.Methods Select 80 patients with mild hearing loss,including 40 sensorineural hearing loss people which is set as sensorineural group,and 40 conductive hearing loss people which is set as conductive groups.20 young and 20 older people were selected in each group,and 20 young normal hearing people and 20 older normal hearing people were selected as control group.6 group with total 120 subjects,and the proportion of men and women in each group is 1:1.Get 500-4KHz MLD in all groups.Then get speech in noise test result SNR,analyze the factors and the correlation between MLD and SNR.Result MLD difference between frequency was statistically significant(P<0.05)in control group,sensorineural group and conductive group,and each group shows 500Hz MLD>1KHz MLD>2KHz MLD>4KHz MLD.Control group,sensorineural group and conductive group show no significant difference in 500Hz,1KHz MLD values(P>0.05);Sensorineural group get greater 2KHz MLD than the control group(P<0.05).Conduction group get greater 2KHz MLD than the control group(P<0.05);Conduction group get greater 4KHz MLD than the control group(P<0.05).Conduction group get greater 4KHz MLD than the sensorineural group(P<0.05).Age has no effect on all frequency MLD.Gender has no effect on all frequency MLD(P>0.05).Hearing loss lead to a increased SNR(P<0.05).Older people get greater SNR than young people(P<0.05).Gender has no effect on SNR(P>0.05).All frequency MLD have no significance correlation with SNR(P>0.05).Conclusion MLD decrease with increasing frequency,and the 500Hz MLD is the most valuable data.MLD is a stable test which is not effect by the type of hearing loss,age and gender,and can be used to distinguish auditory function disorder patient in hearing loss crowd.MLD and speech in noise test reflect two different processing capacity of auditory system respectively.The two test should be merged for central auditory function assessment.