The Study Of Masking Effect On Chinese

Masking effect is an important psychoacoustic phenomenon. It is a process that thethreshold of one sound is raised for the emergence of another sound (maskee). Suchphenomenon has important application values in sound information science such as audiocompression algorithm, speech enhancement, information hiding and so on. One hundredyears have passed since Wegel and Lane published their first article on masking in1924,though we had a great achievement on masking, still no one can say that the laws andmechanism of masking have been completely made clear. The main reasons are that thesubjects’ physical sizes are not the same, human neural physiological is not fully understanditself is very complex. For the reasons above, we carry out further study on masking effect inthis paper on the basis of previous work. We expect a further understanding of its workingmechanism, and then apply it in scientific and practical fields.The research of simultaneous masking is the most important part in masking effect.Simultaneous masking is the masking effect in the condition that the masker and maskee existsimultaneously. The studies in this paper are based on simultaneous masking experiments.The work in this paper can be divided into three parts, in the first part of the work, wemeasured the simultaneous masking thresholds of10Chinese subjects when masker’s SPL is70dB and analyzed the data according to the experimental results. First of all, we calculatedthe average rising and falling slope of the masking curve and verified the phenomenon of"Masking spread upward". Then we compared the measured value to the theoretical valuefrom linear interpolation when masker’s SPL is70dB, founded that linear interpolation effectis remarkable. Finally, we modified the spread function according to the experimental data toachiceve a more accurate spread function that fits to the Chinese people’s characteristic.In the second part of the work, we had a preliminary study on masking effect of elderly.The elderly have varying hearing loss because of its own physical reasons, especially in highfrequency region. Disappointly, the study of it is almost blank previously. Because the studyof this experiment can help to further understand the structure of the ear canal filter and itsmechanism, also it can help to provide the evidences for carrying out the health strategy of protecting the elders and developing hearing-aid products. So we measured the simultaneousmasking thresholds of the aged in this paper on the basis of critical bands and simultaneousmasking. From this work, we founded some useful laws and conclusions.In the last part of the work, we had a preliminary study on masking effect with differentposture. Compared to the factors such as the type of signals, space distribution or thesymmetry of signals in right and left ear, the importance of posture in masking effect still notget enough research. So we measured the masking thresholds under two postures of uprightposture and supine posture. Then we analyzed the datas and made some conclusions. Theresults from the posture masking study can be applied in space and medical equipmentresearch fields, especially in the research with unconventional sitting position. Though theexperiment is just an exploratory research, it still has a very important significance.