In simple terms a sound that is 57 dB would be in the normal noise floor of any decent sized city. In other words you would not hear it unless pretty close. At 97 dB, you could hear it for many thousands of feet away.
Every 10 dB you double the noise energy of an event so a 97 dB event is 16 times as loud as a 57 dB event. Its been awhile, I might not be saying that exactly right.
