A digital tuning method comprising: determining a tuning target period; receiving an audio signal from an instrument to be tuned; obtaining a plurality of different segments of the audio signal starting at times that correspond to integer multiples of the target period; producing waveform samples from the segments; and causing presenting an effect of a succession of waveform segments by: displaying at same display position said segments so that the shape of the waveform appears to move on the display at a speed and direction directly dependent on a difference of a wave period of the audio signal to be tuned and the tuning target period; or producing a combination signal for employing wave interference by adding an inversed first waveform segment representing an earlier portion of the received audio signal to a second waveform segment representing a subsequent portion of the audio signal; the first segment and the second segment being based on portions of the audio signal starting at different integer multiples M of tuning target period T, wherein M is an integer greater than or equal to zero; and outputting the combination signal for indicating tuning of the audio signal; characterized by adjusting the tuning target period depending on a difference between the wave period of the audio signal to be tuned and the tuning target period; and setting the tuning target period back to an original value of the tuning target period when the difference between the wave period of the audio signal to be tuned and the tuning target period meets a given closeness criterion. determining a tuning target period; receiving an audio signal from an instrument to be tuned; obtaining a plurality of different segments of the audio signal starting at times that correspond to integer multiples of the target period; producing waveform samples from the segments; and causing presenting an effect of a succession of waveform segments by: displaying at same display position said segments so that the shape of the waveform appears to move on the display at a speed and direction directly dependent on a difference of a wave period of the audio signal to be tuned and the tuning target period; or producing a combination signal for employing wave interference by adding an inversed first waveform segment representing an earlier portion of the received audio signal to a second waveform segment representing a subsequent portion of the audio signal; the first segment and the second segment being based on portions of the audio signal starting at different integer multiples M of tuning target period T, wherein M is an integer greater than or equal to zero; and outputting the combination signal for indicating tuning of the audio signal; characterized by displaying at same display position said segments so that the shape of the waveform appears to move on the display at a speed and direction directly dependent on a difference of a wave period of the audio signal to be tuned and the tuning target period; or producing a combination signal for employing wave interference by adding an inversed first waveform segment representing an earlier portion of the received audio signal to a second waveform segment representing a subsequent portion of the audio signal; the first segment and the second segment being based on portions of the audio signal starting at different integer multiples M of tuning target period T, wherein M is an integer greater than or equal to zero; and outputting the combination signal for indicating tuning of the audio signal; characterized by adjusting the tuning target period depending on a difference between the wave period of the audio signal to be tuned and the tuning target period; and setting the tuning target period back to an original value of the tuning target period when the difference between the wave period of the audio signal to be tuned and the tuning target period meets a given closeness criterion. <EOS>