| The sound quality of the appliance has become a significant component in the purchaser's overall subjective evaluation. The sound of the appliance used to be evaluated by the noise level measured in dB (A). However, in some cases, the noise level measured in dB (A) can't match the feeling of people. So the validity of traditional objective-quantifiers in acoustics is being questioned. This is because the evaluation using dB (A) criterion includes an A-weight filtering to compensate a sensitivity of human hearing. An under estimation of the hearing effects by the low frequency noise could be happened. That is to say, even if the A-weight sound level is small, the low frequency noise may annoy to listener by the different ways from the high frequency noise. So it is necessary to understand psychoacoustics in order to make noise quality evaluations that match the subjective experience of the purchaser. In this paper, the author established the model of objective evaluate parameters of sound quality and developed an objective evaluation system which could give quantitative objective evaluate parameters, such as loudness, sharpness, roughness, psychoacoustics annoyance (PA) etc. Paper also describes an subjective evaluation investigation ir "'hich 16 subjects used pair comparison statistical evaluation methods to evaluate the noise character of room air-conditioners, the results show that there is generality good agreement between quantitative objective evaluate sound quality parameters and subjective evaluation. At the same time an example of application of the technique to improve the noise character of room air-conditioner is offered. After exhaust pipe and fan system are modified, the total loudness is reduced from 11.5 to 9.6 sone, the fluctuation strength and sharpness are reduced. At the end of this paper, a standard of subjective and objected evaluation method of room air-conditioner is also offered. |
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