The threshold of hearing is the minimum sound level that a person can hear when no other sounds are present. This point will vary from person to person, but is typically reported as the RMS sound pressure of 20 micropascals or 2×10
−4 dynes per square centimeter - that equals 0 dBSPL.
The threshold of pain is the point at which pain begins to be felt. It is an entirely subjective phenomenon. The pressure at which sound begins to feel painful is the pain threshold pressure. It starts with 20 pascals or 120 dBSPL to be painful.