Burtt used many of MacDonald's items on WALL-E.
For EVE, Burtt wanted her humming to have a musical quality.
Burtt described the robot voices as"like a toddler…
universal language of intonation.
Ben Burtt as WALL-E(Waste Allocation Load Lifter: Earth-Class), the title character.
Burtt began work in 2005,
and experimented with filtering his voice for two years.
Burtt had visited Niagara Falls in 1987
and used his recordings from his trip for the sounds of wind.
Sound designer Ben Burtt created the voice of the Dark Overlord by altering
Jeffrey Jones' voice as his character transformed.
He praised Burtt's sound design, saying"If there
is such a thing as an aural sleight of hand, this is it.
Producer Jim Morris recommended Ben Burtt as sound designer for WALL-E because Stanton kept
using R2-D2 as the benchmark for the robots.
As for the iconic sound of the lightsaber, Ben Burtt stated,“the very first sound I created
for the film was the lightsaber.
Burtt was only able to provide neutral or masculine voices,
so Pixar employee Elissa Knight was asked to provide her voice for Burtt to electronically modify.
Most of the characters do not have actual human voices, but instead communicate with body language and robotic sounds,
designed by Ben Burtt, that resemble voices.
Because Burtt was not simply adding sound effects in post-production,
the animators were always evaluating his new creations and ideas, which Burtt found an unusual experience.
Burtt also used an automobile self starter for when WALL-E goes fast, and
the sound of cars being wrecked at a demolition derby provided for WALL-E's compressing trash in his body.
Burtt's accomplishment was such that the Academy of Motion Picture Arts
and Sciences presented him with a Special Achievement Award because it had no award at the time for the work he had done.
Burtt had completed Star Wars: Episode III- Revenge of
the Sith and told his wife he would no longer work on films with robots, but found WALL-E and its substitution of voices with sound"fresh and exciting.