June 25, 2013
Vocal Training Could Help Alleviate Voice Loss In The Elderly
redOrbit Staff & Wire Reports - Your Universe Online
Researchers have successfully used vocal training to reduce some of the voice problems experienced by older rats and their work could ultimately lead to new treatment options for aging humans experiencing similar issues.University of Illinois speech and hearing science professor Aaron Johnson and colleagues from the University of Wisconsin explain that the aging process can cause the muscles of the larynx (the organ which contains the vocal folds) to atrophy.
The vocal folds of a healthy and young larynx completely open and close during the vibration, the authors said. However, this is not the case in older men and women suffering from a condition known as presbyphonia, which prevents the vocal folds from closing properly and results in a gap during vocal fold vibration.
According to Johnson, a second cause of presbyphonia symptoms is degradation of the neuromuscular junction, which is the interface between the nerve that signals the vocal muscle to function and the muscle itself.
In healthy individuals, once the signal reaches neuromuscular junction, it triggers a release of chemicals that causes the muscle to contract. However, age-related decline of the neuromuscular junction can result in muscular weakness and/or fatigue. As a result, the weakness causes a person to have a weak or breathy voice, and to become fatigued due to the extra effort required to speak.
In some cases, doctors can correct the gap between the vocal folds using surgery and injections, but in many cases, neither is a viable option for elderly presbyphonia patients. The good news, the authors said, is the condition might be treatable with vocal training.
Johnson said he was inspired to “become interested in what we can do as we get older to keep our voices healthy and strong” because of his previous experience working with seniors as a former classical singer and vocal instructor. “We know exercise strengthens the limb musculature, but we wanted to know if vocal exercise can strengthen the muscles of the voice,” he added.
To examine whether or not voice training could be used to alter the strength and physiology of human vocal muscles, Johnson and his colleagues opted to use a rodent model.
While the ultrasonic vocalizations made by rats are above the range of human hearing, computers and special recording equipment can be used to lower their frequency so that people can hear them. Both rats and humans use similar neuromuscular mechanisms to vocalize, making the rodents excellent models for the study of human vocal characteristics, according to Johnson’s team.
Old and young male rats were used for both the treatment and control groups. In the treatment group, a female rat was introduced into a cage with a male, and once he expressed interest in her, she was removed. This caused the male rat to vocalize – a behavior which was rewarded with food.
“After eight weeks of this operant conditioning in which rewards were only given for certain responses, all of the rats in the treatment group had been trained to increase their number of vocalizations during a training session,” the Champaign, Illinois university explained.
“At the end of the eight-week period, the researchers measured the intensity of the rats’ vocalizations and analyzed the animals’ larynges to see whether the training had any effect on the condition of their neuromuscular junctions,” they added.
The study authors discovered both the trained older rats and the trained younger ones had similar vocal intensities, but the untrained older rats had lower average intensities than the trained rats and the untrained younger ones. Furthermore, the authors found multiple age-related differences within the groups’ neuromuscular mechanisms.
“Other research has found that in the elderly, there is a dispersion, or breaking apart, of the neuromuscular junction at the side that is on the muscle itself. We found that in the older rats that received training, it wasn’t as dispersed,” Johnson said.
He added these so-called singing rats provide the “first evidence that vocal use and vocal training can change the neuromuscular system of the larynx,” and even though the study did not involve humans, he believes it demonstrates that people “can train ourselves to use our voices and not only reduce the effects of age on the muscles of our voices, but actually improve voices that have degraded.”
The results of this research appear in The Journals of Gerontology.