| 摘要 |
PURPOSE:To realize the good approximation of an optional spectrum at a fraction power type amplitude scale. CONSTITUTION:The transmission function H(z) of a digital filter to be attained is obtained as H(z)=[H0(z)]- (1) and in the form of the power of the transmission factor H0(z) of an appropriate digital filter. Thus the amplitude characteristics¦H(e<j> )¦, (where OMEGA=omegaDELTAt, omega: frequency and DELTAt: unit delay tume of digital filter of the filter is shown as¦H(e<j> )¦=¦H0(e<j> ) ¦- (2). Then a digital filter of H0(z) is selected to have the good approximation to the spectrum G(OMEGA) of a fraction amplitude scale of (1/lambda) power type. Accordingly the desired filter has a lambda-stage connection for the function H0(z). It is generally said that the level of a sound audible with an ear is proportional to about 1/2 square of the amplitude spectrum, i.e. lambda=2. Thus a synthetic sound having high acoustic properties can be obtained with this filter. |
