抄録
It is known that most impulsive sounds are noisier than others with equal acoustical energy. The perceived noisiness of impulsive sounds, however, cannot satisfactorily be assessed by established methods. In order to clarify the nature of the perceived noisiness of repetitive impulses, three series of psycho-acoustical experiments were performed in an acoustically treated listening room. Six to eight trained subjects were requested to adjust the level of the continuous sound to the impulses to achieve the equal perceived noisiness in Experiment I , and were requested vice versa in Experiment II and III. Stimuli included fifteen time-patterns of electrically generated repetitive impulses. Several interesting findings were obtained by these experiments, which were organized in a proposal named the Perceived Noisiness Model of Repetitive Impulses 82-A. It consists of the energy effect and the impulsive effect, and is expressed as in the following formula. PSE = Leq + IE_<max>・exp(-α・RR)・exp(-β・DT)・(1 - exp(-γ・DR))・1/(1 + δ・exp(- ε・BBL)) where PSE=continuous sound levek of equal noisiness in dBA Leq=equivalent sound level in dBA RR=repetition rate per second DT=decay time in msec. DR=duration of each pulse in msec. BBL=background-to-burst level in dBA IE_<max>=hypothetical maximum value of impulsive effect in dBA α, β, γ, δ, ε=constants obtained by experiment
