To provide a portable telephone set capable of performing the optimization processing of a head transmission function in consideration of an individual difference such as the shapes of the head and ears of a user and correctly localizing a sound image, and to provide a sound adjustment method.
The sound adjustment method includes: sound image localization processing for performing sound image localization processing in a sound source signal by using the head transmission function, thereby generating an output sound signal; sound signal output processing for outputting the output sound signal, with the sound image localization processing performed therein, as sample sound; display processing for announcing the output of the sample sound and also displaying a message to request the input of a sample sound incoming direction; and head transmission function correcting processing for correcting the head transmission function, based on the inputted sample sound incoming direction.
KAWAGUCHI TAKASHI
Tadahiko Inaba
Kanako Murakami
Nakatsuru Kazutaka