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Animal hearing

Small animals went high because high sounds can be located. Large animals went low because low sounds travel. It is the same physics read from both ends.

Hearing ranges vary enormously, and the variation is not random: small animals that need to locate things went high, large animals that need to be heard a long way went low. Both directions are the same physics read from opposite ends.

A hearing range is usually presented as a fact about an animal, and it is better understood as a consequence of two constraints pulling in opposite directions. High frequencies have short wavelengths, which is what makes them locatable: a sound only casts an acoustic shadow across a head if its wavelength is small compared with the head, so a small animal that needs to know where a sound came from has to hear high. High frequencies also attenuate quickly and are blocked by anything in the way, so they do not travel. Low frequencies do the reverse — they carry for kilometres, bend around obstacles, pass through vegetation and, at the extreme, through the ground — and they are correspondingly hard to localise, which is a cost a large animal can afford because it usually already knows roughly where its family is. Elephants and baleen whales sit at one end of this, bats and many rodents at the other, and the ranges you can look up in a table are the outcome. Two cautions apply to those tables. A published range depends heavily on the criterion used, so numbers from different laboratories are often not comparable. And an audiogram describes what an animal can detect in a quiet booth, which is not what it can use in a noisy world — the gap between the two is where most confident statements about animal hearing quietly fail.

Early coverage · 35% complete · reviewed 2026-09-02

What this page covers

Hearing ranges have been measured across mammals, birds, amphibians, some reptiles and a growing number of fish and invertebrates. The comparative data are much better for mammals than for anything else.

Often confused with: Sensitivity, which is how quiet a sound can be and is a different measurement from which frequencies are audible

Quick facts

Why large animals go low
Low frequencies travel much further and bend around obstacles
Why small animals go high
Short wavelengths cast a shadow across a small head, which is what makes them locatable
The cost of going low
A sound that carries for kilometres is very hard to place
Published ranges
Depend on the criterion used, and are often not comparable between studies

Why the big animals went low and the small ones went high

Low sounds carry much further than high ones through air, vegetation and water. That physical fact, more than anything about the animals, explains who communicates at long range and who does not.

Established

Specialists would state this without hedging. Multiple independent lines of evidence agree.

Atmospheric and aquatic attenuation increase with frequency, so low-frequency signals suffer less absorption and scattering over distance. Species communicating over kilometres — elephants, baleen whales, some birds in dense habitat — use correspondingly low fundamental frequencies, while short-range and high-resolution signals such as echolocation use high frequencies.

Who this applies to
A physical constraint on sound propagation, applying wherever animals signal acoustically.
Studied in
Animalia
Why we rate it this way, and what the caveats are
EstablishedHigh confidence

The physics is not in dispute, and the comparative pattern across unrelated long-range signallers is exactly what it predicts.

How far it can be extended

The frequency dependence of attenuation is a property of the medium, and the comparative pattern across long- and short-range signallers follows it closely.

Caveats

  • Range is not the only pressure: low frequencies are harder to localise and harder for a small animal to produce.
  • Habitat matters as much as frequency — dense vegetation and temperature gradients change everything.
  • Comparative patterns of this kind are consistent with the physics rather than tests of it.

Still unanswered

  • How much of the variation in signal frequency within a habitat is explained by transmission as opposed to by competition for acoustic space.

Last reviewed 2026-09-02

The evidence (3 studies)
Approximate. Published ranges vary with the criterion used and are frequently not comparable across studies.
AnimalRoughlyWhat the range is for
ElephantDown into infrasound, below human hearingContact across kilometres of bush
HumanAbout 20 Hz to 20 kHz, falling with ageGeneral purpose; speech sits in the middle
DogExtends well above oursSmall prey, and small prey are quiet and high
BatFar above ours, into tens of kilohertzEchoes off insects, which need short wavelengths
MothTuned narrowly to the frequencies bats useOne job: hearing the bat first

The moth is the entry worth pausing on, because it shows how specific a hearing range can get. A noctuid moth’s ear is about as simple as an ear can be — in some species two receptor cells — and it is tuned to the band that bats hunt in. It cannot hear another moth. It is not a general-purpose sense that happens to be narrow; it is a bat detector, and the rest of the acoustic world is not its problem.

Words used here
Infrasound
Sound below the bottom of human hearing, roughly under 20 Hz. Travels a long way, and is used by elephants, some large birds and baleen whales.
Ultrasound
Sound above the top of human hearing, roughly over 20 kHz. Locatable and short-range, which is why echolocating animals use it.
Audiogram
A curve of the quietest sound an animal can detect at each frequency. It is measured in quiet conditions, which is why it overstates what an animal can use in the field.

Knowing where a sound came from

A different problem from hearing it, solved with two ears and — in some animals — hardware we do not have.

Locating a sound means comparing the two ears: which one it reached first, and which one it reached louder. Both comparisons get harder as a head gets smaller, because the two ears are closer together and because a low-frequency wave passes around a small head without casting much of a shadow. That is the constraint that pushed small mammals up the frequency scale, and it is why an animal that hunts by ear is almost always an animal that hears high.

  • Barn owls have ears set at different heights, so a sound arrives at different times vertically as well as horizontally — giving elevation as well as direction, and allowing a strike in complete darkness.
  • Many insects and frogs have ears connected internally through an air passage, so each eardrum is driven from both sides and the animal gets a directional response from a body far too small to compare arrival times.
  • Cats and many other mammals move their ear flaps independently, changing the filtering rather than the timing.
  • Some parasitoid flies locate a singing cricket with an ear a millimetre across, using a mechanical coupling between the two eardrums that amplifies a difference of nanoseconds.

Related

What is still unsettled

  • How much of a laboratory audiogram survives contact with a noisy environment?

    Why it matters: Detection thresholds are measured in quiet, and most animals live somewhere loud. The usable range is narrower than the published one by an amount nobody has characterised for most species.

    What would settle it: Threshold measurement against realistic background noise, which is standard in human audiology and rare in comparative work.

  • How much do invertebrates hear?

    Why it matters: Hearing has been found in an increasing number of insects, spiders and even plants’ visitors, often after being assumed absent. The comparative picture is incomplete in a way that keeps producing surprises.

    What would settle it: Broad screening rather than case-by-case investigation, which is slowly happening.

  • What does anthropogenic noise actually do to animals that rely on hearing?

    Why it matters: Shipping noise overlaps the band baleen whales communicate in, and traffic noise overlaps birdsong. That there is an effect is established; how large it is remains contested.

    What would settle it: Long-term population studies with noise measured directly rather than inferred from proximity.

Claims about this, checked

Things people have heard, and what the evidence actually supports.

The research behind this page

3 studies, newest first. Each one has a page explaining what it found and what it could not show.

2013Oxford University Press

Sensory Ecology, Behaviour, and Evolution

Sensory systems are shaped by the physics of the environment and by the specific tasks an animal performs, and no sensory system is general-purpose: sensitivity in one dimension is routinely traded against resolution, speed or energy in another.

2001BioScience

Echolocation by insect-eating bats

Call structure tracks foraging habitat closely.

1986Behavioral Ecology and Sociobiology

Infrasonic calls of the Asian elephant

Elephants produce powerful calls with fundamental frequencies below about 20 hertz, at the edge of or below human hearing, and these calls accompany social behaviour that had appeared silent.

This page is a stop on a longer route

A guided journey reads several subjects in a deliberate order, with an argument for why one follows another. You can join in the middle.

Where to go from here

Each of these follows from something on this page — a relationship in the evidence, a claim people ask about, or the next mechanism along.

How complete this page is, and what it is still missing

NatureHQ publishes its own gaps. This page is at 35% completeness against what we would call a finished subject, and was last reviewed on 2026-09-02. It carries 1 claims and answers 4 mapped search questions.

  • 1 high-priority search intent(s) not yet covered
  • no research from the last few years is attached — check for newer work
  • more experiments could be explained in plain English
  • The ear itself — how a cochlea separates frequencies, and how differently birds and reptiles do it — is not described.
  • Underwater hearing, which is a different problem because the ear’s impedance advantage disappears, is not covered.
  • Hearing loss, ageing and noise damage in wild animals are absent.