How does Arthur Dent see English vocalizations, not Vogon ones?

Question

When Ford Prefect shoved the Babel Fish in the ear of Arthur Dent, he is able to understand and comprehend speech by Vogons instead of hearing the screeches of their native language. But in the film, the Vogon's animations show their lips moving in such a fashion that it could be lip-read as normal Earth English.

The out of universe explanation is simple, and that is because it would be a bit weird to see Vogons screeching their native language but hear them speaking comprehensible English.

So how is this possible in universe? Is the Babel Fish capable of changing vision as well as hearing?

Answer 1

There's no reason why it could change the sound but not the vision to a listener who cares about the lip movements. You see, the Babel fish isn't like a headphone, it doesn't just whisper the translation to your ear. Let me quote The Hitch Hiker's Guide to the Galaxy chapter 6.

‘The Babel fish,’ said The Hitch Hiker's Guide to the Galaxy quietly, ‘is small, yellow and leech-like, and probabliy the oddest thing in the Universe. It feeds on brainwave energy to nourish itself with. It then excretes into the mind of its carrier a telepathic matrix formed by combining the conscious thought frequencies with nerve signals picked up from the speech centres of the brain which has supplied them. The practical upshot of all this is that if you stick a Babel fish in your ear you can instantly understand anything said to you in any language. The speech patterns you actually hear decode the brainwave matrix which has been fed into your mind by your Babel fish.[’]

Also, let me quote chapter 5 for the description of what using a Babel fish felt like to Arthur. Note that at that time he was listening to a loudspeaker without seeing the Vogon captain, so there was no way to see the lips.

He was still listening to the howling gargles, he knew that, only now it had somehow taken on the semblance of perfectly straight-forward English.

From this, I think the Babel fish simply gives you the meaning of the Vogon speech, and it's your brain that creates the illusion of the sound of English words or the lip movements for them. That experience would be impossible to show in a movie with current technology, so the movie simply shows the Vogon speaking English.

Answer 2

You are focusing too much on one alien species.

If you expect the Vogons lips to move differently to English, then so should the lips of every character. Including Zaphod Beeblebrox, Ford Prefect, Slartibartfast, etc. None of them are native English speakers, no matter how human they look.

Now consider:

• The film's budget in dubbing everyone.
• The entire thing would look like a badly dubbed chop-socky opus

In short - it's a comedy, don't overthink it.

Answer 3

Sadly, in the books, Douglas Adams neglected to elucidate on alien lip synchronisation in relation to Babel fish third party observations. So, here is my guess. The reason the Vogons lips are moving in English is because ifs a film. If the vocals didn't sinc with lip moments it would look like someone had messed up the animatronics in the vogon mask. Also, and more to the point, it would have looked silly.