Symbols are plotted on the audiogram at the quietest level at which the client can detect the frequency. This level, at which the tone can just be detected, is called a threshold.

For instance, the quietest level at which this individual could detect a 2000 Hz tone was at 80 dB.

Therefore, they also responded to the 2000 Hz tone when it was presented at 90 dB, 100 dB, etc., but they did not respond (or respond consistently enough) at 75 dB, 70 dB, 60 dB, 50 dB, and so on. The sound needed to be presented at a louder volume (at least 80 dB) in order for the individual to detect it.