August 23, 2012
Similarities Between Operatic Soprano Singers And Helium-Huffing Monkeys Detailed
John Neumann for redOrbit.com - Your Universe Online
If you are not a fan of opera music, you may have already assumed the similarities of a classic music form and the shrieks of helium-huffing monkeys. Researchers in Japan however, have released a study detailing similarities between such primates, gibbons in particular, and professional soprano singers.
A gibbon´s song is acoustically unique among primates, with a melody which can be heard over two miles away. Wild gibbons use their voices to communicate with neighboring pairs, strangers and potential mates through visibility-poor jungle.
“The complexity of human speech is unique among primates as it requires varied soft sounds made by the rapid movements of vocal tracts,” said Dr. Takeshi Nishimura from the Primate Research Institute at Kyoto University, Japan.
“Our speech was thought to have evolved through specific modifications in our vocal anatomy. However, we´ve shown how the gibbons´ distinctive song uses the same vocal mechanics as opera singers, revealing a fundamental similarity with humans,” he added.
Exemplified by sopranos, control of this nature was thought to be unique to humans, however humans and primates share a great deal of biological equipment for sound production. This biology includes the vocal folds vocal tract - the upper esophagus, trachea and the mouth, which are well known in humans to shape sung notes and subtle vowel sounds.
The human vocal tract acts as a filter on the sound from the source, and the “source-filter theory” held that the separate, fine control of the vocal tract to be the product of a long evolution in the development of the subtleties of speech, writes Jason Palmer, science and technology reporter for BBC News.
Exploring the similarities, the researchers conducted the first acoustic investigation on non-human primates using helium gas, which, as every kid knows, makes human voices sound high pitched. The lighter-than-air gas is useful for studying animal vocal mechanisms as it increases sound velocity and resonance frequencies.
Twenty gibbon calls were recorded in normal air atmosphere, before recording 37 calls in a helium-enriched atmosphere. The resulting sounds reveal how gibbons can consciously manipulate their vocal cords and tract to make their distinctive sound.
“The lowest frequency of harmonics is amplified in a gibbon´s song when performed in normal air,” said Nishimura. “However, in a helium-enriched atmosphere the tuning of the vocal cord vibration and the resonance of the vocal tract are altered as the gas causes an upward shift of the resonance frequencies.”
Nishimura explained that the results upended a long history of research suggesting the control humans use is the product of a long line of physiological and anatomical changes under the influence of evolution.
“The present study challenges that concept and throws new insight into the studies on biological foundations producing the diversifications in primate vocalizations, including human speech,” Nishimura said.
“It is hoped that this study will encourage researchers in various research fields to conduct further investigations of primate vocalizations and that such empirical evidence will lead to a deeper understanding of the evolution of speech and language.”