Humming: a vocal standard with a diurnal variation.
The process of humming can be used as a basal vocal measurement which can be repeatedly obtained with an accuracy comparable to that of other physiological variables. Studies have shown a diurnal fluctuation of the hum frequency. Data were collected by employing automatic telephone-answering equipment.
D002940:Circadian Rhythm; D010507:Periodicity; D013016:Sound
PERIODICITY; SOUND