Headphone and headphone state detection method

A headphone state detection method, applied to a headphone, the headphone comprising a first sound playing unit, a first audio receiving unit, a sensing unit, and a signal processor, wherein the headphone state detection method comprises the following steps performed by the signal processor:

• (a) receiving a sensed signal generated by the sensing unit, and determining a contact state based on the sensed signal;
• (b) in response to that the contact state is in no contact, sequentially sending a plurality of pieces of code information to the first sound playing unit such that the first sound playing unit plays a plurality of first audio signals corresponding to the code information according to a playing sequence, and determining a wearing state of the headphone according to a plurality of first time points when the first audio receiving unit receives the first audio signals subjected to first reflection, wherein any two pieces of continuously sent code information among the code information are in correspondence to different frequencies, and
• (c) in response to that the contact state is in contact, stopping sending the code information.