Respiratory therapy apparatus includes an expiratory vibratory therapy device (100) of the kind that produces an alternating resistance to expiration through the device. The apparatus also includes a sensor (30) that is strapped to the chest of the patient. The sensor (30) includes a three-axis accelerometer (36) responsive to vibration in the chest and a display (34) on which the frequency of chest vibration and the length of the therapy session are represented. The display (34) can be switched between an upright and inverted configuration so that it can be viewed by the patient looking down at the sensor (30).
