US Patent 7822212 Method and system for amplifying auditory sounds

This invention relates to a system for amplifying a sound in an auditory environment. The system comprises a microphone for transforming said sound to an electric sound signal; a band-pass filtering means connecting to said microphone and outputting a filtered sound signal; and an amplifier amplifying said filtered sound signal and outputting a filtered and amplified sound signal to a loudspeaker. The band-pass filtering means comprises a passive first filter having a first bandwidth and first gain, an active second filter having a second bandwidth and a second gain larger than said first gain, and an active third filter having a third bandwidth and a third gain larger than said second gain.