Purpose: Disuse atrophy of swallowing-related organs due to an excessive decrease in swallowing frequency is suspected to occur in patients with poor oral intake, especially elderly people. However, swallowing frequency in elderly or dysphagic patients during daily life has not been examined previously. We developed a small swallowing frequency meter that does not restrict daily activities and can work for a long time. This study assessed the validity of the swallowing frequency meter.

Subjects and Methods: The subjects of this study were 10 healthy young people. The swallowing frequency meter consisted of a laryngeal microphone, which was placed on the neck during recording, and an MP3 recorder. The number of swallowing times was counted by auditory judgment of the sound recorded by the meter and visual judgment of the sound waveform. Two examiners (A and B) participated in this study. We examined: 1) the concordance rate between the number of swallowing times counted by videofluorography and that counted by the frequency meter. Examiner A counted the number of swallowing times on videofluorography, and examiner B counted the number of swallowing times on the frequency meter; 2) the concordance rate between the number of swallowing times counted by the subjects themselves and that counted by the frequency meter. Both examiners A and B counted the number of swallowing times on the frequency meter.

Results: 1) The concordance rate between videofluorography and the frequency meter was 100%. 2) The concordance rate between the frequency meter and the self-counting was 97.1±4.3% (A) and 98.4±4.0% (B) at rest, and 94.9±5.2% (A) and 96.2±7.9% (B) during meals.

Conclusion: These findings indicated that the frequency meter is useful for measuring the frequency of swallowing during daily life.