This application relates to an apparatus (300) for monitoring an operating temperature condition of a microphone device (100) having an acoustic port (110). The apparatus includes a spectrum peak detect block (301) for receiving a microphone signal (SMIC) and determining, from the microphone signal, a resonance frequency (fH) and a quality factor (QH) of a resonance (202) associated with the acoustic port of the microphone. A condition monitoring block (302) is configured to determine any change in resonance frequency and quality factor with respect to respective reference values of resonance frequency and quality factor and to determine a temperature condition for the air temperature within the acoustic port based on said determined changes.