In this guide
Frequency describes how often a periodic vibration repeats, measured in hertz (Hz): 440 Hz means 440 cycles per second. It relates to perceived pitch for simple tones, while amplitude and loudness describe different properties. Real recordings often contain many frequencies at once.
Comparing broadband test signals? See pink noise vs white noise and how their frequency balance differs.
Sound frequency describes how often a periodic vibration repeats. It is measured in hertz (Hz), or cycles per second: a 440 Hz sine wave completes 440 cycles each second. For a simple steady tone, higher frequency generally corresponds to a higher perceived pitch. Frequency is different from how loud the sound is.
A voice, instrument or recording usually contains many frequency components at once. Frequency is useful when describing a note, locating a hum or understanding an equalizer, but one frequency number rarely describes a complete sound. OpenStax's wave guide explains cycles, frequency and amplitude.
What do Hz and kHz mean?
One hertz means one cycle per second. One kilohertz (kHz) means 1,000 Hz. Frequency says how quickly a repeating pattern cycles; the duration of a recording says how long it lasts.
| Example | Meaning | Useful comparison |
|---|---|---|
| 100 Hz | 100 cycles each second in a steady periodic tone. | One quarter the frequency of 400 Hz. |
| 440 Hz | 440 cycles each second. | A common A4 tuning reference, not a volume setting. |
| 880 Hz | 880 cycles each second. | Twice 440 Hz, or one octave above that reference tone. |
| 2 kHz | 2,000 cycles each second. | The same frequency written in a different unit. |
Frequency, pitch and loudness
Frequency is a physical property; pitch is a perception. For steady sine tones, a higher frequency normally sounds higher in pitch. Complex sounds contain a fundamental and other components, and their perceived pitch is not necessarily the strongest frequency in a spectrum. The pitch guide explains notes and octaves. The National Academies' hearing reference discusses the relationship between physical sound and perception.
Amplitude describes the size of a signal's variation; loudness is the perceived strength of a sound. A 440 Hz tone can be played quietly or loudly without changing its frequency. Decibels describe a level or ratio, not a frequency. Digital dBFS and acoustic sound-pressure levels use different references, so a digital file's level alone does not tell you how loud a speaker is in a room.
Low, middle and high frequencies in audio
Audio editors often divide the spectrum into broad regions. The boundaries are convenient labels, not separate boxes: voices, instruments and noise can overlap across them.
| Approximate region | Examples to listen for | Editing caution |
|---|---|---|
| 20–125 Hz | Deep bass, kick weight or low rumble. | A low cut may reduce unwanted rumble and wanted bass together. |
| 125–500 Hz | Body or warmth; sometimes a buildup that sounds muddy. | Judge in context before cutting a range. |
| 500 Hz–2 kHz | Energy from many voices and instruments. | A peak may be a musical note, not a defect. |
| 2–8 kHz | Some consonants, attacks and presence. | Boosting may also emphasize harshness or sibilance. |
| 8–20 kHz | Some cymbal detail, air or hiss. | Playback and hearing vary; do not assume the range is equally audible to everyone. |
The often-cited human hearing range is roughly 20 Hz to 20 kHz, but actual audibility depends on the listener, sound level and equipment. See the National Academies' hearing overview. Do not increase playback volume to force an inaudible tone to become audible.
Frequency and wavelength
Wavelength is the distance a wave travels in one cycle. In a given medium, wavelength equals wave speed divided by frequency. For example, using an approximate speed of 343 meters per second in air, a 100 Hz tone has a wavelength of about 3.43 meters; a 1,000 Hz tone has a wavelength of about 0.343 meters. Temperature and medium affect sound speed. OpenStax describes this relationship.
Try a tone and inspect a recording
- Use the free tone generator to create a short 440 Hz sine-wave WAV. Start playback at a low, comfortable device volume.
- Create an 880 Hz tone at the same digital peak setting and compare their pitch. The two files have different frequencies; equal digital peaks do not guarantee equal perceived loudness.
- To inspect real audio, use the audio spectrum analyzer on a supported short file. Select a moment and compare the visible peaks with what you hear. A spectrum snapshot shows frequency content at that moment, not the identity of each source.
The generator and analyzer run locally in the browser. Neither is a calibrated hearing test or sound-pressure meter. A single peak cannot prove that a sound is unwanted, and equalization affects all sources that occupy the changed range.
Common questions
Is frequency the same as sample rate?
No. Sound frequency describes a repeating component of the signal; sample rate describes how many digital samples are taken per second. See audio sample rate.
Does a higher frequency mean a louder sound?
No. Frequency and signal level are different properties. Perceived loudness also depends on frequency, listening level and playback conditions.
Can I remove one instrument by cutting its frequency?
Usually not cleanly: instruments and voices can share frequencies and harmonics. An EQ changes the selected range in everything present, while source separation is a different estimate with its own artifacts.