There's an old adage that it takes more muscles to frown than in takes to smile, but singing takes the muscle biscuit. When we sing, we use around 100 muscles in the throat, face, jaw, lips, tongue and chest. The sound starts in the larynx, or voice box, by the vibrations of the two vocal folds, controlled by a variety of muscles, which also manipulate pitch and volume. Muscles in the mouth, lips and tongue alter the sound as it passes through.
Now, a new way of taking magnetic resonance imaging videos will allow researchers to study exactly how all these parts of the neck and face work together in perfect harmony to produce beautiful music.
"The fact that we can produce all sorts of sounds and we can sing is just amazing to me," said Aaron Johnson, affiliate faculty member in the Bioimaging Science and Technology Group at the Beckman Institute and assistant professor in speech and hearing science at the University of Illinois.
"Sounds are produced by the vibrations of just two little pieces of tissue. That's why I've devoted my whole life to studying it: I think it's just incredible."
Johnson, who spent 10 years as a professional chorus singer, is particularly interested in the changes aging produces on the vocal system.
"The neuromuscular system and larynx change and atrophy as we age, and this contributes to a lot of the deficits that we associate with the older voice, such as a weak, strained, or breathy voice," he said.
"I'm interested in understanding how these changes occur, and if interventions, like vocal training, can reverse these effects. In order to do this, I need to look at how the muscles of the larynx move in real time."
To do this, Johnson used an MRI machine capable of taking video in real time at a rate of 100 frames per second, without losing resolution, a technique developed at the Beckman Institute. Typically, MRI machines can only take video at a rate of 10 frames per second, which is inadequate to capture the rapid tiny movements of the tongue and other muscles in the head, face and neck.
Last year, UK-based musician Sivu created a music video by laying in an MRI machine and singing; however, the footage was shot over a period of around three hours and later stitched together into a seamless movie. The Beckman Institute's technique is filmed in real time and requires no editing.
"The technique excels at high spatial and temporal resolution of speech -- it's both very detailed and very fast. Often you can have only one these in MR imaging," said Brad Sutton, technical director of the Institute's Biomedical Imaging Center and associate professor in bioengineering at the University of Illinois.
"We have designed a specialised acquisition method that gathers the necessary data for both space and time in two parts and then combines them to achieve high-quality, high-spatial resolution, and high-speed imaging."
Johnson's team is currently investigating whether group singing activities with older adults will help maintain, or even improve, the structure of the larynx, resulting in more powerful voices.