The invention provides a system suitable for monitoring the usage of a toothbrush, the system comprising: (a) a toothbrush; (b) a sound sensor which is located in or on the toothbrush; (c) a programmable data logger which is located in or on the toothbrush, the data logger incorporating a motion sensor and a data store for the logging of data; (d) switching means for triggering the operation of the sound sensor in response to initial signals of toothbrush motion generated by the motion sensor, and (e) a data analysis device which is adapted to analyze data transmitted or acquired from the system to provide information about tooth brushing behavior; in which the duration of data logging is controllable in response to the combined signals received from the sound sensor and the motion sensor respectively.