What the Elderly Can Learn from Singing Rats - Hear One Sing Now
Aging takes its toll on the human body—not the least of which causes the elderly not only to look old, but to sound old as well. However, sounding old may change according to research from scientists at the University of Wisconsin who demonstrated that vocal training of older rats encouraged to sing reduces some of the voice problems related to aging.
In a new study published in The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, scientists explain that sounding old has to do with the normal aging process that is known by the medical term “Presbyphonia.”
Presbyphonia is due to structural and biochemical changes in the larynx that causes changes in how a voice sounds. The changes include a decrease in muscle surrounding the vocal cords, thinning of mucosal tissue that cover the vocal folds and biochemical changes in proteins and other components of the mucosal tissue in the larynx.
Both physical and biochemical changes in the aging larynx leads to incomplete closure of the vocal folds that in turn reduces the dynamic range of a voice as well as interfere with normal vibration activity in the larynx that can give a characteristic “frog” feel and sound in the throat. Nerve interactions with vocal muscles are also affected in the aging larynx that often results in a pronounced wobble or tremor in the voice.
According to a press release issued by the University of Wisconsin, researcher Aaron Johnson, who had previous experience working with the elderly as a former classical singer and voice teacher, became interested in finding ways to help the elderly sound young again.
“We know exercise strengthens the limb musculature, but we wanted to know if vocal exercise can strengthen the muscles of the voice,” said Johnson.
In his research, Johnson turned to the rat as an animal model of study due to that rats have similar neuromuscular mechanisms used to vocalize when communicating with other rats―especially when attempting to mate.
The rat larynx produces ultrasonic vocalizations that are out of the range of human hearing. However, by using specialized recording equipment and software the researchers were able to lower the frequency of rat vocalizations so that they could hear the calls (singing) of rats under a variety of testing conditions.
In the study, male rats both young and old were divided into test and control groups. The test group rats were presented individually with a female rat, which was then removed as soon as the male rat began to show some romantic interest in the female. Upon removal of the female rat, the male rat would typically vocalize as if in protest, but then given a treat by its handler.
The giving of a treat during each induced vocalization is a type of operant conditioning that rewards the male rat for “singing” and thereby increases the frequency of singing during a training session by the researchers.
After 8 weeks of this operant training, the intensity of the vocalizations and the larynxes of young and old male rats from both groups were measured and compared to determine whether the trained older males had an improved voice over the non-trained control group males.
What the researchers found was that:
• Both trained old and young rats had similar average vocal intensities
• Untrained older rats had lower average intensities than both the trained rats and the young rats that had not been trained.
• There are several age-related differences within the groups’ neuromuscular mechanisms.