A method of monitoring speaker temperature for speaker protection starts by generating a low level inaudible noise signal and injecting the low level inaudible noise signal in an audio signal. The voice coil resistance estimate that estimates a resistance of a voice coil of a speaker is then computed. The voice coil resistance estimate changes while the speaker is being driven by the audio signal that includes the low level inaudible noise signal. The temperature estimate is then computed based on the voice coil resistance estimate. The level of the audio signal may be adjusted based on the temperature estimate. Other embodiments are also described.