| 摘要 |
A tone generation system and method generates tone signals having complex harmonic components while reducing aliasing noise resulting from sampling of high frequency harmonics. In a first step, waveshape data which has been sampled with a second sampling frequency which is higher than a first sampling frequency is obtained. Then a predetermined tone synthesis modulation operation is performed, using this waveshape data as at least one of a signal to be modulated and a modulating signal. By performing this modulation operation in accordance with the higher second sampling frequency, occurrence of an aliasing component contained in a tone signal obtained as the output of the modulation operation in a frequency band below a frequency which is 1/2 of the first sampling frequency can be prevented. Then, the frequency band of the output signal of the modulation operation is limited to a frequency band below the frequency which is 1/2 of the first sampling frequency. By this arrangement, even if an aliasing noise component concerning the second sampling frequency occurs in a frequency region which is higher than the frequency which is 1/2 of the first sampling frequency, such aliasing noise component will be eliminated. Lastly the output signal of the third step is resampled with the first sampling frequency. In this manner, in a tone signal generated in response to the resampled signal, an aliasing component concerning the first sampling frequency becomes higher than 1/2 of the first sampling frequency so that it does not appear as the aliasing noise.
|
