--- title: "Hearing and Balance: Frequency, Place and Head Motion" description: "The cochlea sorts sound by frequency mechanically, so position along it stands for pitch before any neuron is involved. The same kind of hair cell, placed in fluid-filled loops instead, reports how th" canonical: https://lightmysky.com/learn/science/hearing-and-balance-frequency-place-and-head-motion-mt_qzPAt9JMOZ source: https://lightmysky.com/learn/science/hearing-and-balance-frequency-place-and-head-motion-mt_qzPAt9JMOZ.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Hearing and Balance: Frequency, Place and Head Motion The cochlea sorts sound by frequency mechanically, so position along it stands for pitch before any neuron is involved. The same kind of hair cell, placed in fluid-filled loops instead, reports how the head is turning, which is why one organ serves two senses. Subject: Science · Area: The Human Body · Ages 20 to 21 Page: https://lightmysky.com/learn/science/hearing-and-balance-frequency-place-and-head-motion-mt_qzPAt9JMOZ ## Ready when they can - Explain the place code for frequency and what part of the cochlea does the sorting - Describe hair cell transduction and why it is fast enough to follow sound - Say how the semicircular canals and otolith organs report different kinds of head motion ## Lesson: How the ear sorts pitch and motion **Example.** Your cochlea sorts pitch mechanically, before any neuron fires, so you can follow a voice or a tune. High-frequency waves bend the basilar membrane near the base; low-frequency waves bend it near the apex. Each hair cell thus serves one frequency, like touch receptors serve one kind of touch, so the membrane reads sound the way a prism reads light. Above the membrane sits the organ of Corti, its hair cells crowned with tilted rows of stereocilia tied together and leaning into the tectorial sheet. When the membrane moves, the sheet slides and bends the bundles: toward the tallest hairs, tethers yank ion channels open and the cell fires; toward the shortest, channels close. Direct mechanical gating is why hearing keeps up with sound. The same kind of hair cell works in balance. The utricle and saccule weigh tilt and straight-line motion with otolith crystals sliding on gel. The three semicircular canals sense rotation: turning the head leaves fluid lagging, which bends the cupula and its hairs. Comparing canals maps any spin in three dimensions. **Tip.** Together the membrane's hair cells encode 20 to 20,000 hertz, apex low and base high. Their signals leave through the vestibulocochlear nerve, and brainstem nuclei compare the ears to pin down where sounds live. **Recap.** Place along the membrane picks the pitch, bent bundles open the current, and twin organs track tilt and spin. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Ion Channels: Selectivity, Gating and the Evidence from Single Channels](https://lightmysky.com/learn/science/ion-channels-selectivity-gating-and-the-evidence-from-single-channels-mt_2xPzPeXZZ_) - [Touch, Temperature and Pain](https://lightmysky.com/learn/science/touch-temperature-and-pain-mt_rnSuJA4-kj) - [Conduction Speed: Myelination and the Refractory Period](https://lightmysky.com/learn/science/conduction-speed-myelination-and-the-refractory-period-mt_x3M0sv6oD6) ## Opens up - [Motor Control: From Intention to Muscle](https://lightmysky.com/learn/science/motor-control-from-intention-to-muscle-mt_hrWOuRtPDl)