An intra aural probe for monitoring multiple physiological parameters simultaneously. The probe includes a pressure sensor, a temperature sensor and a light sensor. The probe is dimensioned to fit snugly and sealingly within the outer aural cavity. The probe measures blood pressure and pulse rate and volume of blood by detecting contraction and expansion in the vascular bed of the lining tissue of the external auditory canal during the cardiac cycle. The probe also measures respiratory rate and respiratory volume by detecting pressure changes across the tympanic membrane or movement of the tympanic membrane induced by corresponding pressure changes in the naso-pharynx and trachea during respiration. In addition, the probe measures temperature in the auditory canal, measures electroencephalographic voltages or electrocardiographic voltages by measuring small potential differences between the external auditory canal region and a suitable reference position, measures electroencephalographic currents by measuring magnetic flux, and measures changes in oxygen saturation of the haemoglobin traveling in the capillary bed lining the external auditory canal.