Patent ID: 8515090

Claim:
An ambient noise removal device for a headphone speaker, the ambient noise removal device comprising: an interface that connects the headphone speaker; a sound signal output section that connects to the headphone speaker via the interface and outputs a sound signal to thereby drive the headphone speaker; a noise detection section, including an equivalent circuit of the headphone speaker, that detects an electromotive force produced in the headphone speaker by ambient noise; an equivalent circuit setting section that sets the equivalent circuit depending on the headphone speaker connected to the interface; and a noise cancellation section that generates, on the basis of the electromotive force, a signal of an opposite phase from the ambient noise and adds the generated signal to the sound signal to thereby cancel the ambient noise, wherein the noise detection section detects the electromotive force, produced by the ambient noise, by obtaining a difference between a first electromotive force produced in the headphone speaker in response to the sound signal output section driving the headphone speaker on the basis of the sound signal and a second electromotive force produced in the equivalent circuit by inputting the sound signal to the equivalent circuit.