ABSTRACT
Objective To investigate the influence of long-term sound conditioning on the physiology of outer hair cells.Methods Twenty healthy guinea pigs were exposed to a broadband noise for 14 days consecutively at the level 90 dB(A),8 h/day.The DP-gram and input/output(I/O)function(1~8 kHz)were measured at pre-conditioning,fourteen days conditioning,seven days post-conditioning and fourteen days post-conditioning,respectively.Results The results of DP-gram measurements demonstrated that long-term sound conditioning could enhance the DPOAE amplitudes within low frequencies(1~3 kHz,especially 5.0 dB at 2 kHz and 7.5 dB at 3 kHz,P
ABSTRACT
Objective To develop a portable and automatic quick screener for noise-induced hearing loss(NIHL),which is suitable for airman and ground crew.Methods Through using audio decoder chip VS1003 to achieve quick screener for noise-induced hearing loss and pre-exposing for special background noise.LPC2148 of ARM7-TDMI configuration was adopted as main controlling chip,and its software design was completed by multitask scheduler based on UCOS-Ⅱ,while the FAT system controlled the read-write to the files in SD card.The signal emergence,change in hearing class,frequency selection as well as records of subject reaction were automatically achieved.Results The system can produce stable signal of exact frequency according to GBZ49-2002 Diagnostic Criteria of Occupational Noise-induced Hearing Loss to output stability of the frequency and intensity of the audio signal,and the specific context of the noise pre-exposure function with screening of hearing impairment was achieved automatically.Conclusion Based on the great power of embedded system and VS1003,the portable and automatic quick screener for noise-induced hearing loss(NIHL) can be developed to carry out many functions,which has several features,such as simple structure,high integration,good stability and use of flexible etc.