The spectrum of a 1 kHz tone. A sound will not be heard if it is under the threshold in quiet. This limit changes around the masker frequency, making it more difficult to hear a nearby tone. The slope of the masking threshold is steeper toward lower frequencies than toward higher frequencies, which means it is easier to mask with higher frequency tones. (Photo credit: Wikipedia ) A Layman's Guide to EQ Frequency : number of cycles per unit time (measured in hertz, Hz) - A sound at 1Hz only has one cycle per second (making it a low, an inaudible pitch) - A sound at 20 kHz has 20000 cyles per second (an extremely high pitch usually outside the human range of hearing...your dog might hear it though) - Human range of hearing can be from 20Hz to 20kHz -Orchestras tune to A440 (at 440 Hz) It is important when mixing to determine the general frequency range of your instruments, sounds, and voice tracks in order to EQ properly. Excess noise, for example,...