Frequency is how many times a sound wave repeats each second, measured in hertz (Hz), and it is what your ear hears as pitch. Repeat faster and the sound is higher; repeat slower and it is lower. It is one of the three things that describe any sound, sitting alongside how loud it is and the shape of the wave, and it is the one that decides which note you are hearing.
This is true of any sound in any tool, a synth, a plugin, a DAW or a browser instrument. Hertz is hertz wherever you meet it, and none of this is tied to one product. The band figures further down are rough and rounded, since sources draw the lines in slightly different places.
Frequency is how many times a sound wave repeats per second, and it is measured in hertz (Hz). Sound travels as fast, tiny changes in air pressure, and most musical sounds come from a wave that repeats, cycling through the same shape over and over. Count how many of those cycles happen in one second and you have the frequency. One hertz is one cycle per second, so a wave at 100 Hz repeats a hundred times a second. Because the numbers climb quickly, they are often written in kilohertz, where 1 kHz is simply 1000 Hz.
What you hear as frequency is pitch. A faster vibration, meaning a higher frequency, sounds higher, and a slower vibration, a lower frequency, sounds lower. A tight or short string vibrates quickly and sounds high; a loose or long one vibrates slowly and sounds low. Everything from a deep bass note to a thin whistle is the same idea running at a different speed.
Frequency is not the same as level or shape. Frequency is how fast the wave repeats, heard as pitch and measured in hertz. Amplitude, or level, is how big the wave is, heard as loudness and measured in decibels. The waveform is the shape of the wave, heard as its character or timbre. A sound can change one without changing the others: turn a note up and its frequency stays exactly the same, it just gets louder.
The range of human hearing runs from roughly 20 Hz at the low end to about 20 kHz at the high end. Below about 20 Hz a vibration is felt more than heard, and above about 20 kHz it passes out of hearing altogether. That span covers everything music asks of it, from the deepest bass you can sense in your chest to the finest air and shimmer at the top.
The top end is not fixed. It drops as we age, and after years of loud sound it drops faster, so many adults hear little above 15 or 16 kHz and notice nothing missing in everyday listening. This is normal and not something to worry about. It is worth knowing, though, because the highest band is where much of what we call air and brightness lives, and two people can honestly disagree about it simply because they do not hear the very top the same way.
20 Hz to 20 kHz is the textbook range, and it is a useful average rather than an exact boundary for any one person. The low end is fairly stable across a lifetime; the high end is the part that changes. When a chart or a plugin marks the audible range, this is almost always the span it means.
Every musical note is a particular frequency, and the two are tied together by one simple rule: doubling the frequency raises the pitch by exactly one octave. Notes are named and tuned by their frequency, and the usual reference point is the A above middle C, which is tuned to 440 Hz. This is the note orchestras tune to and the default that most instruments and software are set to, though some ensembles pick a slightly different value on purpose.
From that reference, an octave is a doubling. The A one octave above 440 Hz sits at 880 Hz, and the A one octave below sits at 220 Hz. Keep doubling or halving and you keep moving by octaves, which is why the same note name repeats up and down the keyboard: each one is double the frequency of the one below. The smaller steps between octaves, the individual semitones, are spaced by other even ratios, but the octave is the easiest to hold on to because it is just twice the frequency.
The A above middle C is 440 Hz. Double it to 880 Hz and you have the A one octave up; halve it to 220 Hz and you have the A one octave down. Every octave is a doubling of frequency, which is the one number relationship in pitch that is worth memorising, since it holds for any note, not just A.
Frequency matters for mixing because a mix is not one sound but many playing at once, all sharing the same frequency range. When two parts crowd the same region, they mask each other and the result turns muddy or harsh. A clear mix comes from giving each part its own space, so the ear can pick out every element. The main tool for that job is EQ, which raises or lowers particular frequency ranges so that a kick and a bassline, say, are not both fighting for the same low end.
It helps to think of the range in rough bands. The names below are common shorthand, and the exact boundaries vary from one engineer to the next, so treat them as a map rather than hard lines.
| Band | Rough range | What tends to live there |
|---|---|---|
| Sub-bass | 20 to 60 Hz | Deep rumble and weight, felt as much as heard; the lowest kick and bass energy. |
| Bass | 60 to 250 Hz | The body and fundamental of bass and kick, and the low end of most instruments. |
| Low mids | 250 to 500 Hz | Warmth and fullness; the region where a crowded mix most easily turns muddy. |
| Mids | 500 Hz to 2 kHz | The body of most instruments and voices, and much of what carries a melody. |
| High mids | 2 to 4 kHz | Attack, edge and presence; strong here reads as forward, too much as harsh. |
| Presence | 4 to 6 kHz | Clarity and definition; helps voices and lead parts cut through a mix. |
| Air | 6 to 20 kHz | Openness, sparkle and shimmer; cymbals, breath and the top of almost everything. |
None of this replaces good recording and arrangement. If two parts sit in the same range and play at the same time, no amount of EQ fully hides that they are competing, which is why choosing sounds that already occupy different parts of the range is half the battle. Frequency is the lens that makes all of this visible: once you hear a mix as a stack of bands rather than one wall of sound, deciding what to cut and what to lift gets a great deal easier.
A fader changes how loud a whole part is; EQ changes how loud each frequency range within that part is. If a vocal is buried, turning it up on the fader makes everything about it louder, while lowering a competing instrument's mids with EQ can clear a space for it without raising the whole mix. Frequency thinking is what tells you which of the two a problem really needs.
Frequency is far easier to manage when the parts arrive in different places to begin with. You can carve space with EQ all day, but a mix comes together fastest when the sounds were not fighting for the same range in the first place.
The Collection is our three instruments together, ARGISH, SILT and REHEAT, with three separate licence keys. A clear mix starts with sounds that each own their part of the frequency range, and these instruments are voiced to sit cleanly in a mix without fighting for the same space, which leaves you less to untangle with EQ later. ARGISH is a self-playing chord synth, SILT is a tape-loop instrument, and REHEAT writes acid lines, and whatever you make with them is yours to release. Each one ships as AU, VST3, AAX and a standalone app on macOS, signed and notarized, and a VST3 on Windows.
You can hear one free in your browser first, no install and no account, then decide.
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