A noise reduction circuit, a noise reduction apparatus and a noise reduction method

A mixed signal which contains a noise is input. Then, the signal is inverted and amplified by an inverting amplifier (4) which has a high gain, and attenuated by a attenuator (5) in order to generate an inverted phase signal. In a mixer (6), the input signal and the inverted phase signal are added, and output. Since the inverted phase component of the noise is added to the noise, the noise in the mixed signal is canceled. For the voice signal, an amplified inverted signal is generated by an inverting amplifier (4). However, the amplitude thereof is restricted due to a high gain. Since the amplitude is restricted, a level of the inverted phase signal is lower than a level of a voice signal. Even if the voice signal and the inverted phase component are added in the mixer (6), the voice signal is output almost thoroughly.