Able to be heard. Generally the term audible is used to describe the ability of a human to hear a specific sound (although something that is audible to an animal such as a dog may not be audible to a human). udibility differs from person to person, but the general audible frequency range for people is 20 Hz to 20,000 Hz (or 20 kHz). As people age, they tend to lose hearing at the extremes, particularly in the upper frequencies. The human ear is the most attuned to the middle frequencies in the area of 3,000 Hz. An audio signal is not audible if it is above or below the frequency range of human hearing or if it is not of sufficient amplitude (it is not loud enough). Low frequency signals (those of 80 Hz and below) are non-directional meaning that the human ear cannot locate their source by listening alone.