Physics
Audio Frequency Range
Quick fact
A healthy young human can hear sounds from about 20 Hz (a low rumble) to 20,000 Hz (a high-pitched ring), but this range shrinks with age, typically losing the highest frequencies first.
Why this is interesting
Have you ever wondered why a dog whistle is silent to you but your pet responds instantly? The answer lies in the audio frequency range—the invisible boundary of what your ears can detect.
Read the full explanation
Understanding Audio Frequency Range
Think of sound as waves vibrating through the air. The number of vibrations per second is called frequency, measured in hertz (Hz). The audio frequency range is the set of frequencies that most humans can hear, roughly 20 Hz to 20,000 Hz. Lower frequencies (like a bass drum) produce deep tones; higher frequencies (like a cymbal crash) produce sharp, high-pitched sounds. Our ears are not equally sensitive across this range—they are most sensitive around 2,000–5,000 Hz, which is why speech sounds clear. The range defines what we call 'audible sound' and separates it from infrasound (below 20 Hz, felt as vibrations) and ultrasound (above 20,000 Hz, used in medical imaging).
A deeper explanation
The audio frequency range arises from the physical construction of the human ear. Sound waves enter the ear canal and vibrate the eardrum, which transmits motion through three tiny bones to the cochlea. Inside the cochlea, hair cells along the basilar membrane are tuned to specific frequencies: near the entrance they respond to high frequencies, deeper inside to low frequencies. This tonotopic organization creates a frequency map sent to the brain. The range is limited by the mechanical properties of these structures—the cochlea cannot vibrate fast enough for frequencies above about 20,000 Hz, and below 20 Hz the wavelengths become too long to efficiently couple to the eardrum. Understanding this range is crucial for designing audio equipment (speakers, headphones) that reproduce sound accurately, for hearing loss diagnosis, and for technologies like ultrasound imaging that deliberately use frequencies beyond human hearing.