Processing with an equalizer or filter can have a great impact on the perceived sound. To correctly identify the sound characteristics of different frequency ranges, the following clues can help:
| Frequency range | Frequencies | too less | just right | too much |
| subbass/ bass/ Upper bass | up to 250 Hz | thin | powerful, rich | booming |
| lower mids | 250 – 750 Hz | cold | warm | muddy |
| upper mids | 750 Hz – 3 kHz | lax | crispy | intrusive |
| lower highs | 3 – 8 kHz | muffled | present | sharp |
| upper highs | above 8kHz | muffled | brilliant | spiky, hissy |
Frequencies and pitch
All tones and octaves are related to frequency. In order to tune instruments correctly, it has been determined that the pitched A is at a frequency of 440Hz. This tone is called “concert pitch” and corresponds to A3 on a MIDI keyboard. From this frequency all tones can be derived, because an octave up or down always corresponds to a doubling or halving of the frequency.
Example tone A:
A0 = 55 Hz
A1 = 110 Hz
A2 = 220 Hz
A3 = 440 Hz
A4 = 880 Hz
A5 = 1760 Hz
A6 = 3520 Hz
A7 = 7040 Hz
A8 = 14080 Hz
In some EQs, a keyboard can also be displayed, which can then be used to assign frequencies to individual tones.
