The signal processing apparatus receives an input acoustic signal, and amplitude-modulates the received input acoustic signal to generate an output acoustic signal having an amplitude change corresponding to a frequency of a gamma wave, and outputs the generated output acoustic signal.

A method for stringed instruments' pickup, the method comprising a step of: capturing mechanical vibrations of at least one string; and converting them to a signal representative of a string's current state, the method being characterized in that the capturing comprises the following steps: capturing, using an image capturing device, image frames comprising views of at least one musical instrument's string in a still state; storing the captured image as a reference of a still state; capturing (500), using the image capturing device, image frames comprising views of at least one musical instrument's string in a vibrating state; storing the captured image as a reference of a vibrating state; comparing (520) the still state reference with a vibrating state reference in order to find (530) amplitude of vibrations of each string as well as frequency of each string vibrations based on amplitude height in pixels with reference to the still state and determining a frequency of each vibrating string on the basis of the number of pixels between two nuts of at least half-period of a given periodic function.

A sound generation method that is realized by a computer includes receiving a first feature amount sequence in which a musical feature amount changes over time, and using a trained model that has learned an input-output relationship between an input feature amount sequence in which the musical feature amount changes over time at a first fineness and a reference sound data sequence corresponding to an output feature amount sequence in which the musical feature amount changes over time at a second fineness that is higher than the first fineness, to process the first feature amount sequence, thereby generating a sound data sequence corresponding to a second feature amount sequence in which the musical feature amount changes at the second fineness.

A method for stringed instruments' pickup, the method comprising a step of: capturing mechanical vibrations of at least one string; and converting them to a signal representative of a string's current state, the method being characterized in that the capturing comprises the following steps: capturing, using an image capturing device, image frames comprising views of at least one musical instrument's string in a still state; storing the captured image as a reference of a still state; capturing (500), using the image capturing device, image frames comprising views of at least one musical instrument's string in a vibrating state; storing the captured image as a reference of a vibrating state; comparing (520) the still state reference with a vibrating state reference in order to find (530) amplitude of vibrations of each string as well as frequency of each string vibrations based on amplitude height in pixels with reference to the still state and determining a frequency of each vibrating string on the basis of the number of pixels between two nuts of at least half-period of a given periodic function.