What is the minimun auditery signal people can hear regularly?

Answer 1

Generally from 20 - 20,000 HZ depending on the individual. We lose some high end range as we age

Answer 2

I assume you are asking about loudness, rather than frequency (as in the other answer). Auditory pure-tone thresholds begin at 0 decibels (rarely heard by people unless they have really acute hearing) all the way to 120 decibels. Most people without hearing loss have a pure-tone threshold of abot 5 to 10 decibels.