Signal processing apparatus and signal processing method
A signal processing apparatus receives an input acoustic signal, acquires a first acoustic signal having a periodic variation corresponding to the frequency of gamma waves, and outputs an output acoustic signal based on the acquired first acoustic signal and the second acoustic signal. The second acoustic signal is based on the input acoustic signal.
1 . A signal processing apparatus, comprising:
a memory that stores instructions; and
a processor that executes the instructions stored in the memory to
receive an input acoustic signal;
acquire a first acoustic signal having periodic variations corresponding to a frequency of a gamma wave by amplitude-modulating a partial signal of the input acoustic signal, the partial signal having a predetermined characteristic;
acquire a second acoustic signal from the input acoustic signal; and
output an output acoustic signal based on the acquired first acoustic signal and the acquired second acoustic signal to induce gamma waves in a brain of a user.
2 . The signal processing apparatus according to claim 1 , wherein
the first acoustic signal is generated by amplitude-modulating the partial signal of the input acoustic signal using a modulation function with a frequency between 35 Hz and 45 Hz, and wherein
the first acoustic signal has an amplitude change corresponding to a frequency between 35 Hz and 45 Hz.
3 . The signal processing apparatus according to claim 1 , wherein
the partial signal is an acoustic signal corresponding to a sound of a predetermined sound source type.
4 . The signal processing apparatus according to claim 1 , wherein
the partial signal is an acoustic signal corresponding to a sound that is audible to a listener from a predetermined direction.
5 . The signal processing apparatus according to claim 1 , wherein
the partial signal is an acoustic signal corresponding to a sound in a predetermined frequency band.
6 . The signal processing apparatus according to claim 1 , wherein
the partial signal is an acoustic signal corresponding to a sound in a predetermined time period.
7 . The signal processing apparatus according to claim 1 , wherein
the second acoustic signal is an acoustic signal obtained by separating the first acoustic signal from the input acoustic signal.
8 . The signal processing apparatus according to claim 1 , wherein
the first acoustic signal is a signal having pulses with an interval corresponding to the frequency of gamma wave.
9 . The signal processing apparatus according to claim 8 , wherein
the amplitude of the pulse included in the first acoustic signal varies according to an amplitude of the input acoustic signal.
10 . The signal processing apparatus according to claim 1 , wherein
the output acoustic signal has an amplitude change corresponding to a frequency between 35 Hz and 45 Hz.
11 . The signal processing apparatus according to claim 1 , wherein
the input acoustic signal is an audio signal including music content.
12 . A signal processing method, comprising:
receiving an input acoustic signal;
acquiring a first acoustic signal having periodic variations corresponding to a frequency of a gamma wave by amplitude-modulating a partial signal of the input acoustic signal, the partial signal having a predetermined characteristic;
acquiring a second acoustic signal from the input acoustic signal; and
outputting an output acoustic signal based on the acquired first acoustic signal and the acquired second acoustic signal to induce gamma waves in a brain of a user.
13 . The signal processing method according to claim 12 , wherein
the first acoustic signal is generated by amplitude-modulating the partial signal of the input acoustic signal using a modulation function with a frequency between 35 Hz and 45 Hz, and wherein
the first acoustic signal has an amplitude change corresponding to a frequency between 35 Hz and 45 Hz.
14 . The signal processing method according to claim 12 , wherein
the first acoustic signal is a signal having pulses with an interval corresponding to the frequency of gamma wave.
15 . A non-transitory computer-readable recording medium that stores a program which causes a computer to execute a method comprising:
receiving an input acoustic signal;
acquiring a first acoustic signal having periodic variations corresponding to a frequency of a gamma wave by amplitude-modulating a partial signal of the input acoustic signal, the partial signal having a predetermined characteristic;
acquiring a second acoustic signal from the input acoustic signal; and
outputting an output acoustic signal based on the acquired first acoustic signal and the acquired second acoustic signal to induce gamma waves in a brain of a user.
16 . The non-transitory computer-readable recording medium according to claim 15 , wherein
the first acoustic signal is generated by amplitude-modulating the partial signal of the input acoustic signal using a modulation function with a frequency between 35 Hz and 45 Hz, and wherein
the first acoustic signal has an amplitude change corresponding to a frequency between 35 Hz and 45 Hz.
17 . The non-transitory computer-readable recording medium according to claim 15 , wherein
the first acoustic signal is a signal having pulses with an interval corresponding to the frequency of gamma wave.
18 . The signal processing apparatus according to claim 1 , wherein
the second acoustic signal is generated by amplitude-modulating a second partial signal of the input acoustic signal, and wherein
the second acoustic signal has an amplitude change corresponding to the frequency of the gamma wave, and wherein
a modulation degree of the second acoustic signal is different from a modulation degree of the first acoustic signal.
19 . The signal processing apparatus according to claim 1 , wherein the processor executes the instructions to
determine a degree of modulation based on characteristics of the input acoustic signal, and wherein
the amplitude-modulating is performed with the determined degree of modulation.
20 . The signal processing method according to claim 12 , further comprising
causing the user to hear a sound corresponding to the output acoustic signal for cognitive function improvement, wherein
the signal processing method is used for improving cognitive function of the user.