Researchers in Japan have discovered that how effectively we clean our teeth and how satisfied we are with our brushing depends on the sound of the bristles scrubbing against the enamel. In the study, published in the International Journal of Arts and Technology, the team used a tiny microphone in a modified toothbrush to ‘sample’ the sound being made in the mouth during brushing, and to modulate it and then feed it back to the volunteer via headphones to see what effect it had on cleaning efficacy and satisfaction.
The team found that if they manipulated the pitch (frequency and loudness) of the brushing sound they could alter volunteers’ perception of comfort and accomplishment. They also showed that if they gradually increased the frequency as teeth cleaning progressed, volunteers felt that the process was more comfortable and that their teeth were cleaner at the end.
Tooth brushing provides a ‘negative reward’, as people brush their teeth to avoid developing caries. Many people find the task boring, so they do not consider the impact of not brushing until they are suffering from caries or other dental diseases. These results show that it is possible to motivate people by interactively manipulating the frequency of brushing sounds, so that the task becomes more satisfying. The system can also tell, through a built-in sensor, whether a person is brushing too hard, which can damage the gum line, and so give them aural feedback to encourage them to clean more gently.
The prototype system requires the teeth cleaner to wear headphones. However, bone conduction speaker systems could be incorporated into the smart toothbrush so that the amplified feedback loop is created in the mouth.