A system and a method to determine heart and/or breathing rates. The system comprises a shell configured to occlude an ear canal, an in-ear microphone located inside the shell to capture an audio signal inside the ear canal, and a processor operatively connected to the in-ear microphone, the processor being configured to analyse the audio signal in order to determine at least one of a heart beat and/or a respiration rate measurement or attribute, even when the wearer of the system is immersed in high level of environmental noise. The system and method also comprise the use of an adaptive digital filter to remove the residual environmental noise from the audio signal captured by the in-ear microphone. The system and method also comprise the use of a predetermined audio signal association to identify attributes of the captured audio signal inside the ear canal.
