Just been reading an interesting set of posts on the sound_design yahoo group about the use of anthropomorphic sound design to give non-human objects/characters (such as robots) "personalities".
The group members suggest some good examples of such sound design.
The Black Stallion
Lord of the rings
Old Warner Bros cartoons
One member (Craig) points out a nice little example from Jurassic Park:
"in the first part of the film when they are getting the guided tour of
the labs. They are standing over some eggs and a very gentle robotic
arm servo sound is used in handling the eggs. Then Jeff Goldblum
touches one of the eggs and the robotic arm turns aggressive, using a
completely different type of servo sound, one that is more aggressive
and grating. A small detail, but in my opinion, a great use of sound
to convey emotion of a non human character."
Another member (Andy Farnell) provides some good examples of the use of sound to provide a feeling of emotion for robotic characters:
"HAL - measured, cold, soporific. The line "I'm sorry Dave, I can't
allow you to do that" is delivered to juxtapose the life and death
situation against indifferent, emotionless logic. Though later, when
he is (being killed) having his memory circuits ripped out the drunken,
confused rendition of "Daisy" is clearly played for emotions.
Daleks ! :) Pure, arrogant evil of a superior master race hellbent on
exterminating 'inferior' lifeforms. The inharmonic shift of the ring
modulator gives that nasty buzzing (like a wasp) feel. The modulator shift
is used to emphasise manic nihilsim, with the pitching up towards the
end of each phrase or sentence.
Cylons - The vocoder is followed by a tight verb or resonator that makes
them sound like they are speaking out of their hollow metal heads. It's actually
a bit dumb and drone like. While you could imagine Daleks could be formidable
enemies and easily angered, Cylons seem like stupid metal heads any human
could easily outwit.
Robby the Robot - with his pointlessly flailing arms and spinning ears
probably wouldn't be much use in a scrap against ninjas, but the voice
(complementing the 7 foot tall stature) is all about strength and protection,
so when he says "Danger Will Robinson!" you think - ah don't worry Robby
is with them, he'll sort it all out. Good old reliable Robby will save
everyone (by falling on the enemy and crushing them).
Bender - He's just a regular robot. The lack of VO effects emphasises
the lack of difference. Bender is more grounded and human than the other
pretentious residents of the Futurama universe. He gets drunk, watches
roboporn, cheats, steals and lies and acts like a coward. While at
the same time, remains completely lovable.
R2D2 - basically R2 is a dog. He fetches. He does cute tricks. Not big
enough to be a threat, but can bite if he needs to. His purposeful
chatter is intelligent, but seems like it's directed at himself much
of the time. He gets frightened and shrieks.
Notice how Imperial probe droids (which are a similar species to R2)
are made evil with a bit of modulation and inharmonic sidebands."
Another good example is from the Transformers film. In the scene where Bumblebee (the yellow car/robot) is captured by the US army the mechanical groans. creaks, etc all give the impression of the robot being in distress.
The vocals of the robots were also devised in such a way as to help the viewer differentiate between the autobots and deceptecons. The deceptecon voices are pitched down slightly and are processed to give them a slightly sinister edge.
I think its fair to say that creating sounds for a non-human character can be quite an exciting prospect as you are able to provoke emotional responses from the viewers through nothing other than the use of sound design.