An effect device may be configured such that when an input audio signal switches from a consonant to a vowel and an input level of the switched vowel is greater than a threshold value Lc (and a variable t is greater than time Ts), an audio effect signal A may be generated. Such an effect device may allow for increasing the occurrences when portamento is simulated, while still sounding natural. In general, a detecting module detects whether an audio signal is a vowel sound or a consonant sound and whether the audio signal changed from a consonant sound to a vowel sound; and a pitch change module changes a pitch of the audio signal and changes, based on a prescribed function, an amount the pitch is changed to produce a modified audio signal, when the audio signal changed from a consonant sound to a vowel sound.