In a speech enhancement apparatus, a generator part generates a value representing likelihood of a consonant from an input audio signal, and a calculator part generates a consonant/vowel discriminating signal for discriminating a consonant portion and a vowel portion based on the generated value, detects a first signal level of the vowel portion and a second signal level of the consonant portion based on the audio signal and the consonant/vowel discriminating signal, and outputs a level-related signal. A determining part determines a gain coefficient that exceeds one when the second signal level is smaller than the first signal level based on the level-related signal so that the gain coefficient increases as the second signal level becomes smaller than the first signal level. A multiplier part multiplies the audio signal by the gain coefficient to output an audio signal having an emphasized consonant portion.