The Human Hearing Range — What 20 Hz to 20 kHz Really Means
Where does the familiar 20 Hz–20 kHz figure come from, and how high can adult ears actually hear? Including why the ear's sensitivity differs from one frequency to the next.
Published 2026-09-26
20 Hz–20 kHz is the textbook outer boundary
The frequencies people perceive as pitch are usually said to run from about 20 Hz to 20 kHz. The neuroscience textbook Neuroscience (Purves et al.) presents this range and explains that infants can hear slightly above 20 kHz but lose high-frequency sensitivity as they grow, so the upper limit for the average adult is closer to 15–17 kHz.
In other words, 20 kHz is not a line everyone hears — it is closer to an outer boundary that healthy young ears can reach when the sound is loud enough. People differ a lot, and the top end comes down for everyone with age.
Each frequency sounds differently loud
The ear does not hear all frequencies equally well. At the same sound pressure, the region around 2–5 kHz sounds loud, while very low and very high sounds seem quiet. The international standard ISO 226 maps the sound pressure that sounds equally loud at each frequency as 'equal-loudness contours'. One reason is that the ear canal, running from the ear opening to the eardrum, resonates at roughly 3–4 kHz and boosts that band.
So a hearing limit is not defined only by 'how many Hz you can hear' — it also depends on how loud the sound is played. Bass near 20 Hz or treble above 18 kHz needs quite a lot of sound pressure to be heard at all. That is also why changing the volume on this site changes your limit.
Sounds outside the hearing range
- Infrasound (below 20 Hz): felt as vibration or pressure changes rather than pitch. It comes from wind, earthquakes and large machinery.
- Ultrasound (above 20 kHz): people can't hear it, but animals such as bats and dolphins use it, and so does medical ultrasound imaging.
We perceive pitch on a log scale
Going from 100 Hz to 200 Hz and from 1,000 Hz to 2,000 Hz are both one octave, and they sound like similar steps to the ear. The 20 Hz–20 kHz hearing range spans about 10 octaves. That is why this site shows its frequency ruler and sweeps on a logarithmic scale.
How to check it on this site
- High limit tab: records the moment the tone disappears as it rises from 8 kHz to 22 kHz.
- Low limit tab: records the moment it disappears as it falls from 250 Hz to 20 Hz. Earphones and laptop speakers reproduce bass poorly, so the device often hits its limit before your ears do.
- Tone generator: pick a specific frequency and keep listening.
Your result is the narrower of your ears' and your device's limits, and it is not a medical hearing test.
Sources
- Purves D. et al., Neuroscience, 2nd ed. (2001), The Audible Spectrum — NCBI Bookshelf
- ISO 226:2023, Acoustics — Normal equal-loudness-level contours