This study proposes a post-processor to improve the harmonic structure of a vowel in enhanced speech, enabling speech quality to be improved. Initially, a speech enhancement algorithm is employed to reduce background noise for noisy speech. Hence the enhanced speech is post-processed by a block-directional-median (BDM) filter to reduce the musical effect of residual noise. Since the harmonic spectra are impacted by background noise and a speech enhancement process, the quality of a vowel is deteriorated. A harmonic regenerated method is developed to improve the quality of post-processed speech. Experimental results show that the proposed method can improve the quality of post-processed speech by adequately regenerating harmonic spectra.