The importance of how something is said has become a common problem for users of e-mail. If you rely on e-mail, you have probably spent some time trying to straighten out a misunderstanding. You dashed off a message that offended the recipient. You didn't intend it to sound obnoxious. Instead, the recipient detected a nasty tone in your text and took offense.
Tone is so important that when it is omitted people fill it in.
HAL, of course, doesn't have to rely on text-only communication with Frank and Dave. Look Dave, I can see you're really upset about this. I honestly think you ought to sit down calmly, take a stress pill, and think things over. In the novel 2001, Clarke tells us that HAL analyzes Dave's voice harmonics. We also might expect him to be able to interpret Dave's facial expression, as hearing and seeing are the only two perceptual abilities we know HAL possesses.