Propagation delay correction apparatus and propagation delay correction method

A propagation delay time correction method for adjusting a propagation delay time of an audio signal of each of a plurality of channels to suppress sound image localization bias by Haas effect, comprising:

• generating a frequency spectrum signal by performing short-term Fourier transform on the audio signal;
• determining whether propagation delay times for respective frequency bands of a plurality of predetermined frequency bands are changed by a user, if the propagation delay times are changed,
• calculating phase control amounts for respective frequency bands of the plurality of predetermined frequency bands based on the propagation delay times respectively set for the plurality of predetermined frequency bands, the calculated phase control amounts representing a first phase control signal, and generating a second phase control signal by smoothing the first phase control signal in a frequency domain;
• controlling a phase of the frequency spectrum signal for each of the plurality of predetermined frequency bands on a basis of the second phase control signal;
• and
• generating an audio signal on which a propagation delay correction is applied by performing an inverse short-term Fourier transform on the frequency spectrum signal of which the phase is controlled for each of the plurality of predetermined frequency bands.