A patient monitor can diagnose whether its speaker is blocked, malfunctioning, or at a volume that is too low. For example, the monitor can include a processor that can diagnose the speaker by recording a microphone input signal. The processor can compare the microphone input signal to an expected alarm signal that should be output by the speaker. If the two do not match or reasonably correspond to one another, then the processor may increase the volume of the alarm to determine whether doing so can overcome an obstruction, noise, or potential malfunction. The microphone can again detect the speaker output, and the processor can again make another comparison or analysis of the input with the speaker output. If the speaker output as detected via the microphone is still insufficiently loud, then the patient monitor may output an indication that the speaker has a problem.