Equalization (eq) is the process of changing the tonal characteristics of an audio signal. Equalization can either enhance a signal or alter it to create a special effect. In either case, it is a distortion of the original.
People tend to describe what they hear in non-technical, subjective, terms such as:
This can be difficult to translate, but it is your job as the engineer to understand what they mean by these terms. If an accurate interpretation of their description is not possible, ask more questions.
Simply stated “boomy” and “muddy” tend to mean that there is too much bass or low end. “Harsh” refers to an excessive amount of mid-range frequencies, while “bright” and “crisp” indicate too much high end. You need the correct amount of all three areas to create a natural sound.