Speaker recognition experiments have been conducted with the publicly available YOHO database to compare the performance of human listeners and computers. Two types of listening experiments have been performed, one is the forced-choice speaker discrimination test which is corresponding to the task of speaker identification. The second experiment of speaker recognition by human listeners is the same-different judgment which is similar to the task of speaker verification. It is shown that the human listeners perform well for the same-different judgment task, but the error rate of speaker discrimination is relatively large. Besides, human listeners are more robust to session variability, while the machine's performance falls off largely when the reference and test utterances are from different recording sessions.