Distributed May 23, 2002
News Service Contact: Kristen Cole
Some sound effects are better than the real thing, says Brown study
New scientific evidence supports long-time claims by sound effect technicians, known as Foley artists, that exaggerating sounds in movies makes them more believable to the audience. Laurie Heller, assistant professor (research) of psychology, will present her findings June 3, 2002, at the 143rd meeting of the Acoustical Society of America, in Pittsburgh, Pa.
PROVIDENCE, R.I. — Artificial sound effects created to exaggerate the sound of real events were more realistic to listeners than recordings of the actual events, says a recent Brown study that provides insight into how humans identify sounds.
Sound effect technicians, known as Foley artists, have long claimed that exaggerating sounds in movies makes them more realistic to the audience. They recreate a sound such as walking in the mud by recording an unrelated physical event such as squeezing wet newspaper.
Brown researchers mixed successful components of recorded events, such as walking in the mud, and the Foley imitation of the sound, to create a hybrid sound effect that was deemed more realistic than either. More than 70 percent of the time, listeners preferred the hybrid version to either the real or Foley version.
“Caricatures that exaggerate essential facial features have been found to improve recognition,” said Laurie Heller, lead researcher. “Through the study of auditory caricatures, we are interested in discovering what is essential in a sound for its identification.
“When certain features are exaggerated – like in a caricature – it appears to enhance the sound so that it becomes more realistic to listeners. The Foley artists found this through trial and error. I’m interested in finding the scientific basis for it.”
Heller, assistant professor (research) in psychology at Brown, will present her findings June 3, 2002, at the 143rd Meeting of the Acoustical Society of America, in Pittsburgh, Pa.
Researchers first recorded the sounds of nine events and generated corresponding Foley sound effects in the laboratory. Those included the sound of walking through the leaves and its Foley counterpart created by running fingers through a box of Cornflakes; the sound of a crackling fire, and the Foley version created by twisting cellophane.
Both types of sounds were tested for accuracy. Seventeen normal-hearing research volunteers listened through headphones to identify all of the real and Foley auditory events. Neither the real nor the Foley versions stood out as more accurate than the other.
Next, researchers digitally synthesized new sounds out of three pairs of sound stimuli: walking through mud, walking in leaves, and crushing eggshells. They mathematically extracted certain acoustic features – those determined to be the strengths of each – and combined them for the recorded hybrids.
For example, the tempo of walking was extracted from the real recording of a person walking in mud. But the sound of squishing mud came from the Foley version because it better conveyed the material sound, said Heller.
The fact that listeners perceived the hybrid as more realistic than either the real or Foley version points to characteristics of our auditory system that have yet to be explained, said Heller.
The process of recording real events and creating realistic Foley counterparts was intensive. Although recorded sound effects were available through the Internet, researchers created their own recordings because they did not know the materials or events that created the available sounds.
Heller conducted the study with Lauren Wolf, a graduating senior in neuroscience.