The Gauffin and Sundberg technique of assessing masking during vocalization was modified and tested on 22 normal-hearing and 20 hearing-impaired subjects. The masking effect of the vocalized [a:] on narrow-band noise pulses (250-8,000 Hz) and on test reading was studied. The results showed that the female voice was about 4 dB more efficient in masking external speech compared to the male voice and that the female voice had a high-frequency bias of masking the narrow-band noise, whereas the male voice had a low-frequency bias. Subjects with hearing impairment in the high frequencies were particularly impaired by the masking caused by their own voice. The implications for multilogue conversations and auditory rehabilitation are discussed.