What is the Audio Frequency Spectrum?
The human audio spectrum ranges from 20Hz to 20KHz. It means we can hear when air shakes back and forth at 20 times per second, and at 20,000 times per second. Any lower or higher and we don’t detect anything, so our nerves don’t fire so we don’t hear. Your dog can hear from 60Hz-45KHz, which is far beyond the human limits!
Of course, that is the most extreme limits and as we age cochlear nerves die due to excessive loud noises, and natural decay and we lose the upper and lower limits of our range, causing hearing loss. There is actually a temporary form of hearing loss, in which the tip links on the hair cells in your ears lose their functionality (they get broken off by such loud noises), and they will regrow and reform later. But when your cochlear nerves begin to die, usually due to prolonged exposure and over excitation they do not grow back. And thus your current range may vary, check it here.
Visualizer and Audio
Sub Bass
The Sub Bass, section of the human audio range covers the very lowest frequencies: 20-60Hz.

Now humans cannot generally hear 20-60Hz at softer volumes, due to the Fletcher-Munson Curve, so the Sub Bass is the type of bass that people feel, not so much hear. At louder concerts the sub bass is what lends to that electric feeling that your whole body is experiencing the music: because it is. These frequencies are also resonant frequencies of the objects inside of your body, like your bones. So you really feel the Sub Bass in your bones.
Bass
The Bass, Covers the 60-250Hz range of the Audio Spectrum

The Bass is usually where the rhythm of a song lies. Most of the drums and bass have their fundamental frequencies here. Hence, too much Bass makes the song sound like it is thumping. Modern music has the Bass centered around the 100-200Hz range.
Lower Mid-Range
The Lower Mids, Covers the 250-500Hz rangeof the Audio Spectrum

The Lower Mids, as most engineers refer to them, contain most of the fundamentals and lower degree harmonics. This is the basis of most of the sounds inside of a song, and is treated as the foundation of the sounds.
Too much sound in this range, will cause a song to sound muddy. Boosting ~300 Hz adds clarity to the bass, and subtracting in the 500Hz can make other instruments sound less muffled.
Mid-Range
The Mid-Range, Covers the 500-2KHz rangeof the Audio Spectrum

The Mids, are important in instrument placement within a song. An instrument with a strong presence in the Mid-Range will be easily heard and featured in the song. This is the part of the audio spectrum where the sound becomes more brassy, and metallic.
Upper Mid-Range
The Upper Mid-Range, Covers the 2KHz-4KHz range of the Audio Spectrum, (humans are most attuned to this range will probably sound the loudest)

Human language and hearing have co-developed. The sound of predators and important alerts are centered in this range (screaming, a bob cats whine) and that explains why the Upper Mid range is so sensitive to changes.
This range on the audio spectrum can cause fatigue when over-saturated so be careful, but it can add presence to drums, and small changes can alter the timbre of any instrument significantly.
Presence
Presence, Covers the 4KHz-6KHz range of the Audio Spectrum

The Presence range is very important to, well… presence of a sound in a mix. Cuts in this region make a sound more distant, and boosting gives the sound more presence. However, be careful too much manipulation in this range can make a song sound grating and unpleasant.
Upper Range/Highs/Harmonics/Brilliance
The Upper Range, Covers the 6KHz-20KHz range of the Audio Spectrum

The Upper Range, is consists completely of harmonic tones for the instruments used in modern music. This adds depth and an airy quality to the sound of an instrument. Ex: this range is what gives a flute it’s timbre.
Excessive boosting in this range quickly tires the listeners ears. And cutting it will give a noise an artificial feeling.
Take Aways
Range Name | Audio Spectrum Frequencies |
Sub Bass | 20-60Hz |
Bass | 60-250Hz |
Lower Mids | 250-500Hz |
Mid-Range | 500Hz-2KHz |
Upper Mids | 2-4KHz |
Presence | 4-6KHz |
Upper Range | 6-20KHz |