Acoustic signal processing device and acoustic signal processing method

An acoustic signal processing method for an acoustic signal processing device in which an attack component control and a reverberation component control are applied to an input audio signal,

• the acoustic signal processing device comprising:
• an FFT section for transforming the input audio signal from a time-domain signal into a frequency-domain signal to calculate a frequency spectrum signal and for generating a first amplitude spectrum signal and a phase spectrum signal;
• an attack component controller for controlling an attack component of the first amplitude spectrum signal generated by the FFT section to generate a second amplitude spectrum signal;
• a reverberation component controller for controlling a reverberation component of the first amplitude spectrum signal generated by the FFT section to generate a third amplitude spectrum signal;
• a first adding section for synthesizing the first amplitude spectrum signal generated by the FFT section, the second amplitude spectrum signal generated by the attack component controller, and the third amplitude spectrum signal generated by the reverberation component controller to generate a fourth amplitude spectrum signal;
• and
• an IFFT section for generating an audio signal transformed from a frequency domain to a time domain based on the fourth amplitude spectrum signal generated by the first adding section and the phase spectrum signal generated by the FFT section,
• the attack component controller including:
• a first HPF section, a first limiter section, and a first gain section,
• the reverberation component controller including:
• a second HPF section, an amplitude inverting section, a second limiter section, and a second gain section,
• wherein the acoustic signal processing method, comprising the steps of:
• performing a short-time Fourier transform to the input audio signal with time shifted by a differential time between a Fourier transform length and an overlap length to calculate a plurality of amplitude spectra differing in time from one another by the differential time, calculating, on a per frequency basis, a time variation of each of the calculated amplitude spectrum to calculate the frequency spectrum signal, and generating the first amplitude spectrum signal and the phase spectrum signal based on the frequency spectrum signal, in the FFT section;
• applying, on a per spectrum basis, high-pass filtering to the first amplitude spectrum signal generated by the FFT section based on a preset first cut-off frequency by means of the first HPF section of the attack component controller;
• limiting a negative side amplitude of the amplitude spectrum signal that has been subjected to the high-pass filtering by the first HPF section to set the negative side amplitude to 0 to detect, on a per spectrum basis, the attack component of the amplitude spectrum signal by means of the first limiter section of the attack component controller;
• applying, based on a preset first weighting amount, weighting processing to the attack component of the amplitude spectrum signal detected by the first limiter section by means of the first gain section of the attack component controller;
• applying, on a per spectrum basis, high-pass filtering to the first amplitude spectrum signal generated by the FFT section based on a preset second cut-off frequency by means of the second HPF section of the reverberation component controller;
• multiplying the amplitude spectrum signal that has been subjected to the high-pass filtering by the second HPF section by −1 to invert an amplitude of the amplitude spectrum signal by means of the amplitude inverting section of the reverberation component controller;
• limiting a negative side amplitude of the amplitude spectrum signal that has been subjected to the amplitude inversion by the amplitude inverting section to set the negative side amplitude to 0 to detect, on a per spectrum basis, the reverberation component of the amplitude spectrum signal by means of the second limiter section of the reverberation component controller;
• applying, based on a preset second weighting amount, a weighting processing to the reverberation component of the amplitude spectrum signal detected by the second limiter section by means of the second gain section of the reverberation component controller;
• synthesizing the first amplitude spectrum signal, the second amplitude spectrum signal whose attack component has been subjected to the weighting processing by the first gain section, and the third amplitude spectrum signal whose reverberation component has been subjected to the weighting processing by the second gain section to generate a fourth amplitude spectrum signal by means of the first adding section;
• and
• calculating a frequency spectrum signal based on the fourth amplitude spectrum signal and the phase spectrum signal generated by the FFT section and applying an inverse short-time Fourier transform and an overlap addition to the calculated frequency spectrum signal to generate the audio signal transformed from a frequency domain to a time domain by means of the IFFT section.