The invention discloses a protection method for automatically regulating a volume of a 
loudspeaker according to temperature raising of a 
voice coil. The protection method comprises the following stepsof: S1: acquiring a current value and a 
voltage value of an audio of the 
loudspeaker, and carrying out 
Fourier transform on the current value and the 
voltage value; S2: according to a frequency valueafter 
Fourier transform, obtaining an impedance curve of the 
voice coil; S3: reading the impedance curve, searching a nominal impedance RAC of the 
loudspeaker on the impedance curve, and according toa 
voice coil power and tolerance table corresponding to a material of the voice coil and according to a formula that RDC=RAC-XL(f1), obtaining a 
direct current resistance RDC, wherein the XL(f1) represents a voice 
coil inductance inductive impedance of of the loudspeaker under a frequency f1 corresponding to the nominal impedance; S4: carrying out comparison on a resistance value RDC of the acquired 
direct current resistance and a preset standard resistance value to obtain a resistance variation percentage; and S5: according to the resistance variation percentage and a 
metal temperature coefficient, calculating the temperature raising, and when the temperature raising exceeds a preset value, regulating input power of the loudspeaker by an attenuation 
signal. The protection method disclosed by the invention is accurate to monitor, wide in applicability and high in protection.