Patent ID: 7873426

Claim:
A digital recording device comprising: a microphone configured to convert collected sound into an analog audio signal; a first analog to digital converter configured to convert the analog audio signal converted by said microphone into a digital audio signal; a first memory configured to store the digital audio signal of said first analog to digital converter; an attenuator configured to attenuate said analog audio signal with a predetermined attenuation factor; a second analog to digital converter configured to convert the attenuated analog audio signal into a digital audio signal; a second memory configured to store the digital audio signal of said second analog to digital converter; an audio signal generating unit configured to extract the digital audio signal in one of said first memory and said second memory for a required time range according to an amplitude maximum value of said digital audio signal, and generate a new digital audio signal, the audio signal generating unit configured to determine a first zero crossing point before and a second zero crossing point after each amplitude maximum value in the digital audio signal in the first memory that exceeds a threshold, and the audio signal generating unit generating the new digital audio signal by replacing the digital audio signal from the first memory with the digital audio signal from the second memory between the first zero crossing point and the second zero crossing point for each amplitude maximum value in the digital audio signal in the first memory that exceeds the threshold; and an audio signal memory configured to store the new digital audio signal.