Study

Hearing with an atympanic ear: good vibration and poor sound-pressure detection in the royal python, Python regius

Christensen, Christian Bech; Christensen-Dalsgaard, Jakob; Brandt, Christian; Madsen, Peter Teglberg

Journal of Experimental Biology, 2012

Peer-reviewedcontrolled laboratory experimentlaboratory

What they did

Auditory brainstem responses were recorded from royal pythons while airborne sound pressure and substrate vibration were delivered and controlled independently, so the two stimuli could be separated rather than confounded as they are in ordinary conditions.

Studied in: Python regius
Sample size: 11 royal pythons

What they found

The snakes responded to both, with sensitivity to substrate vibration far exceeding sensitivity to airborne sound. Best responses fell in a low band of roughly 80–160 Hz. Airborne sound was detected, but required much higher levels to produce a response.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

Snakes hear, using an ear without an eardrum in which the jaw and inner ear are coupled to the substrate, and they are specialised for low-frequency ground-borne vibration rather than deaf to airborne sound.

How NatureHQ reads it

This is the measurement that retires "snakes are deaf". They are not deaf; they lack an external ear and an eardrum, which is a different statement, and the consequence is a hearing profile rather than an absence. The practical version — a snake notices your footfall long before your voice — is right, and is a fact about what its ear is built for rather than about a missing sense. Note the scope: one species, and a python at that. Snakes vary.

Limitations

A single species, and one adapted to a particular habitat.
Auditory brainstem responses measure what the ear transmits, not what the animal attends to or acts on.
Behavioural thresholds are typically lower than physiological ones, so this may understate sensitivity.