Sound perception begins with air vibrations reaching the ear. The frequency of these vibrations, measured in Hertz (Hz), determines the sound’s pitch. One Hertz represents a single cycle of vibration per second. The human ear converts these physical vibrations into electrical signals the brain interprets as sound. This article defines the typical frequency limits humans can perceive and explores the factors that alter an individual’s hearing range.
The Benchmark: Standard Human Hearing Range
The standard frequency range of human hearing is 20 Hz to 20,000 Hz (20 kHz). Perception also depends on volume, measured in decibels (dB). The dynamic range spans from the softest sounds at 0 dB to painful sounds around 120 to 130 dB. Sounds below 20 Hz are classified as infrasound, and those above 20,000 Hz are known as ultrasound.
While 20 kHz is the maximum potential, this upper limit is typically only observed in children and young adults. Most adults perceive the highest-pitched sounds between 15,000 Hz and 17,000 Hz. This reduction in high-frequency sensitivity is a universal phenomenon that begins relatively early in life.
Why the High-Frequency Limit Changes
The primary reason the upper frequency limit decreases is presbycusis, or age-related hearing loss. This progressive process involves the gradual degeneration of sensitive hair cells located in the cochlea. The cochlea is organized tonotopically, with the hair cells detecting high-frequency sounds situated at the basal turn. Because they are the most susceptible to damage, high-pitched sounds are generally the first to become inaudible as a person ages.
Chronic noise exposure significantly accelerates this high-frequency loss. Repeated exposure to sounds at or above 85 dB, such as loud music or machinery, causes permanent damage to these delicate hair cells. Since these sensory cells do not regenerate in humans, this leads to permanent noise-induced hearing loss. This environmental damage compounds the effects of presbycusis, resulting in an earlier loss of high-frequency hearing.
Practical Assessment: How Frequency Hearing is Tested
A formal evaluation by an audiologist determines an individual’s hearing profile using an audiogram. This graph plots the softest sounds a person can hear, known as the hearing threshold, across various frequencies. The horizontal axis represents frequency (Hz), typically ranging from 125 Hz to 8000 Hz, covering most speech sounds. The vertical axis measures sound intensity in decibels (dB), with quieter sounds appearing toward the top.
During the test, pure tones are delivered through headphones to determine the threshold for each frequency. This air conduction testing measures how well sound travels through the outer and middle ear. Bone conduction testing is also performed to assess the inner ear directly, bypassing those structures. While online frequency sweeps offer rough estimates, a professional audiogram provides the calibrated accuracy necessary for a precise assessment of hearing health.