Acoustic analysis device and a frequency conversion device used therefor

A frequency conversion device comprising:

• sound signal forming means for forming a signal to be radiated by sound radiation means for radiating a sound by storing first digital signal information at a predetermined sampling frequency in first digital memory means, reading out the first signal information at a first sampling clock, digital-to-analog converting the read out signal information to an analog signal and supplying the converted signal to said sound radiation means;
• collected sound reproducing means for reproducing a sound collected by sound collecting means for collecting a sound by analog-to-digital converting an output analog signal waveform from said sound collecting means to a second digital information at a second sampling clock, storing the second digital information in second digital memory means and reading out the stored second signal information at a third sampling clock, wherein said predetermined sampling clock and said third sampling clock are at least twice the maximum audio frequency input to the frequency conversion device;
• sampling clock control means for setting a frequency of the first sampling clock at a value which is n times (n being 1 or over) as high as the predetermined sampling frequency and setting a frequency of the second sampling clock at a value which is n times as high as the frequency of the third sampling clock;
• and
• system control means, coupled to the sampling clock control means and responsive to the reduced scale of the reduced scale model means, for commanding the sampling clock control means to generate frequencies corresponding to the first, second and third sampling clocks and for controlling the input and output of the first and second digital information with respect to the first and second digital memory means.

An acoustic analysis method comprising the steps of:

• producing a reduced scale model of a reduced scale of 1/n (n being 1 or over) of an acoustic space to be measured;
• radiating a sound provided in said reduced scale model;
• collecting a sound provided in said reduced scale model;
• forming a signal to be radiated in said reduced scale model comprising the steps of storing first digital signal information in a first digital memory means, obtaining the first digital signal information by converting an analog signal waveform to be measured at a predetermined sampling frequency, converting the first signal information to an analog signal by digital-to-analog conversion means, reading out the first signal information at a first sampling clock and radiating the converted analog signal;
• reproducing said collected sound and converting an output analog signal waveform from said collected sound to second digital signal information at a second sampling clock, and storing the second digital signal information in a second digital memory means and reading out the stored second signal information at a third sampling clock, wherein said predetermined sampling clock and said third sampling clock are at least twice the maximum audio frequency of said analog waveform to be measured;
• setting a frequency of the first sampling clock at a value which is n times as high as the predetermined sampling frequency and setting a frequency of the second sampling clock at a value which is n times as high as a frequency of the third sampling clock;
• controlling the sampling clock to generate frequencies corresponding to the first, second and third sampling clocks and to control the input and output of the first and second digital signal information with respect to the first and second digital memory means;
• and
• acoustically analyzing the output of said reproduced collected sound.