Wireless earphone, mobile phone and sonic ranging method

A sonic ranging method for a mobile phone and a wireless earphone, comprising:

• the mobile phone performing an acoustic response test on the wireless earphone, comprising:
• the mobile phone generating a first audio sequence at a first time slot and plays an audible sound comprising the first audio sequence;
• when the wireless earphone recognizes the first audio sequence, the wireless earphone generating a second audio sequence to be played in ambience;
• and
• when the mobile phone recognizes the second audio sequence from the ambience, the mobile phone estimates a length of elapsed time according to a time difference between a current time slot and the first time slot;
• and
• when the mobile phone obtains the length of elapsed time, the mobile phone determining a distance between the wireless earphone and the mobile phone according to a delay compensation parameter and the length of elapsed time;
• wherein the delay compensation parameter comprises a length of time required by the mobile phone and the wireless earphone to process the first audio sequence and the second audio sequence.