Most Things Biology

Case home · Start at the beginning · The Reveal

Time To Read

19–28 minutes

Date Last Modified

The Special Senses · Chapter 6 of 7

Hearing is a chain of conversions. Air pressureThe force exerted by gases in the respiratory system, affecting airflow and gas exchange. waves become the movementA fundamental property of life involving motion of the body or its parts. of a membrane; the membrane moves three small bones; the bones drive a fluid; the fluid bends a hair cell; the hair cell fires a nerve. Five translations between a sound in a room and a signal in your headRounded proximal end that fits into the acetabulum of the hip bone., and a fault at any one of them produces deafness — they just produce different-looking deafness, and telling the shapes apart at the bedside is most of what an audiologist does. Stina noticed hers in restaurants. The shape of her audiogram says where in the chain it happened, and the tissue it names is the one tissue in this module that cannot replace what it loses.

The question you will answer

Build the chain first and then break it. The outer and middle ear and the trick the ossicles do with pressure; the cochlea past the oval window, its three ducts and the membrane that sorts sound by place; the hair cell and the stereocilia that open channelsProtein passages in the cell membrane that allow specific molecules to pass through. when they bend; the road up the brainstemThe lower part of the brain that connects to the spinal cord and controls vital functions. to the temporal lobeThe brain region responsible for processing sound and memory.. Then the audiogram: conductive against sensorineural, why the high notes go first, why hair cellsThe basic structural and functional units of life. are a one-way door, and what a slow inflammatory disease can and cannot be said to do in an inner ear.

Opener · Twenty-Fold · about 1¾ minutes

The opener is the same narrated animation you will watch in Scene 1.

Watch it in Scene 1 ↓

Watch the opener first. It sets the question; the chapter answers it.

Read the chart

Patient chart · Stina

2018 · age 43 · the audiologist’s and the ENT’s folders

2018 · 43
Restaurants: hears that people are talking, cannot catch the words; birdsong gone; a thin ringing in quiet rooms (tinnitus). Asks people to repeat themselves and insists she is not going deaf.

2018 · 43
Audiogram: thresholds normal through the low and middle frequencies, dropping at the high frequencies, both ears, symmetric — “earlier than age explains.” Air conductionThe transmission of nerve impulses along neurons. and bone conduction fall together: sensorineural. (Module’s own detail; no dB values are invented; any audiogram shown is drawn from a shape, never scanned.)

2018 · 43
ENT: canals clear, drums intact and mobile, tympanograms normal, Weber midline, Rinne air better than bone both sides. “Nothing to fix; come back in a year.”

Jun 2026 · 51
Dr. Y: a whisper at arm’s length is missed on both sides; tuning fork as above. Cranial nerve VIII, cochlear division, abnormal; vestibular division normal.

Standing
High frequencies live at the baseA substance that accepts hydrogen ions (H⁺) or releases hydroxide ions (OH⁻). of the cochlea; a loss that starts there is a loss in a tissue that does not regrow. Permanent, and worth chasing rather than shrugging at.

Chart clues this module: #12 — Two cranial nervesNerves that arise from the brain and control head and neck functions., a cochlea and an eye under the same tide

Before you go on · your prediction

The drums are intact, the middle ears are clear, the tuning fork is heard better through air than bone, and the audiogram dips only at the high frequencies. The best first reading is…

Open the one you lean toward. Nothing is recorded and nothing is revealed — you come back to it at the end.

Wax or fluid — a blocked ear, fixed by cleaning it

Ask what a block in the canal or middle ear does to all frequencies, and what the tuning fork would have shown.

Hair cells at the base of the cochlea, lost and not coming back

Ask which end of the cochlea reads high notes, why that end goes first under almost every insult, and what “earlier than age explains” means for a woman of 43.

The auditory cortex has stopped understanding speech

Ask whether a cortical problem would show on an audiogram at all, and whether a patient who hears vowels and misses consonants has a cortex problem or a frequency problem.

From Stina’s diary

2016–19 · ages 41–44 · “Ten folders”

The story

Three short movements: the case, the anatomyThe study of the structure of the human body. and physiologyThe study of how the body functions., then the tie back to Stina. Each links to the scene where you’ll see it move.

I · Air to bone to fluid

Sound arrives as pressure waves, which the auricle funnels down the external acoustic meatus onto the tympanic membrane. (the textbook notes that “pinna” is better kept for an ear that can be moved, like a cat’s.) The membrane moves, and behind it, strung across an air-filled middle ear, three small bones move with it: malleus, incus and stapes — hammer, anvil, stirrup — the smallest bones you own, the malleus fixed to the drum and the stapes footplate seated in the oval window of the inner ear. They amplify, but not by adding energyThe capacity to do work or cause change.; the technical term is impedance matching. Air is thin and the fluid on the far side is not, so a pressure wave meeting that fluid directly would mostly bounce off. The ossicles solve it geometrically, funneling the force collected by the large drum onto the far smaller footplate, multiplying pressure something like twenty-fold (the ratio is standard anatomy; the textbook gives the arrangement, not the number). Two tiny muscles — the tensor tympani and the stapedius — stiffen the chain against very loud sound, a fraction of a second too late for a gunshot. The auditory (Eustachian) tube links the middle ear to the pharynxThe muscular passageway connecting the mouth to the esophagus and larynx. and equalizes pressure across the drum; it is normally closed and pops open when you swallow or yawn, which is the whole physiology of the airplane descent. Everything to here is conduction, and a fault anywhere in it — wax, fluid behind the drum from a cold, a stiffened stapes — is conductive hearing loss: the sound never reaches the cochlea at full strength, every frequency is dimmed more or less equally, and turning up the volume fixes it.

See it move: Scene 1 · Outer and Middle

II · Past the oval window

Past the oval window everything is fluid. The inner ear is a bony labyrinth tunneled into the petrous part of the temporal boneBones on the sides of the skull near the ears; house structures of hearing and balance., with a membranous labyrinth floating inside it, and two separate regions share the bone: the cochlea for hearing and the vestibule for balance, their nerves traveling together as cranial nerve VIII. The cochlea is a snail shell of two and a half turns holding three parallel tubes. The scala vestibuli starts at the oval window and runs up to the apex; it bends over the top and comes back down as the scala tympani, ending at the round window, a membrane that bulges outward to give the incompressible fluid somewhere to go. Between them, sealed off, runs the cochlear duct (standard texts add scala media), floored by the basilar membrane and holding the organ that hears. Two fluids, and here the textbook stays silent and the anatomy lab does not: the outer scalae hold perilymph, much like cerebrospinal fluid(CSF) – A fluid that cushions and nourishes the brain and spinal cord.; the cochlear duct holds endolymph, rich in potassium(K⁺): Major ICF cation; essential for muscle and nerve function. like the inside of a cell, kept that way by a strip of capillary bed in the duct’s outer wall, the stria vascularis, which also runs an unusual standing voltage across the duct. The cochlea is a metabolic extremist: two fluids of different composition a hair’s breadth apart, an electrical gradient to maintain, and a single small vessel supply with no collateral circulation to speak of. Hold that; it comes back. The stapes rocks, perilymph in the scala vestibuli moves, and a traveling wave runs along the basilar membrane. The membrane is the clever part. It is narrow and stiff at the base and wide and floppy at the apex, so each frequency peaks the membrane at its own place: high frequencies near the base by the windows, low frequencies at the apex, across the whole human range of 20 to 20,000 Hz. It is often called a prism for sound; the piano stretched into a snail shell is the same idea. That is the tonotopic map, and it means the cochlea has done the analysis before the brain sees anything — pitch is encoded as a position along a spiral, exactly as place along the postcentral gyrusThe area of the parietal lobe responsible for processing sensory input. encodes where you were touched.

See it move: Scene 2 · Past the Oval Window

III · The organ of Corti, and what inflames quietly

The organ of Corti is a strip of sensory epithelium on the basilar membrane holding the hair cells — mechanoreceptorsReceptors that respond to mechanical stimuli such as touch or pressure. named for the stereocilia on their tops, microvilli-like rods arranged tallest to shortest and tethered to one another by fine protein links so the bundle bends as a unit, their tips embedded in the overhanging tectorial membrane. Where the basilar membrane peaks, the hair cells there are pushed against the tectorial membrane and the bundles bend. Bend toward the tallest and tension on the tethers opens ion channels; potassium from the endolymph rushes in, the cell depolarizes and releases glutamate onto a fiber of the spiral ganglion in the bony core, and that fiber fires — the cell does not; it is a common slip, and it is the same one the taste bud invites. Bend toward the shortest and the tethers slacken, the channels close, the fiber quiets; at rest the bundle sits slightly tense and the cell slightly depolarized, so the fiber reports both louder and quieter than silence. Standard anatomy adds: a single row of roughly 3,500 inner hair cells does the actual hearing, and three rows of about 12,000 outer hair cells do something stranger, contracting in time with the sound to sharpen and amplify the membrane’s response — an active tuning system, and the more fragile of the two, so the earliest losses are of clarity rather than volume. Here is the factA statement based on direct observation that is repeatedly confirmed. the chapter turns on: in mammals these cells do not regenerate. Skin replaces itself continuously; the liverA large organ that produces bile, detoxifies blood, and stores nutrients. regrows; the olfactory epithelium you met two chapters ago replaces its neuronsThe functional cells of the nervous system that transmit signals. for life. The roughly fifteen thousand hair cells you were born with are the entire allocation. Lose one and the frequency it read goes quiet permanently, and damage accumulates from the base forward, partly because every traveling wave, whatever its pitch, has to pass the base to get anywhere, and partly because those basal cells are the stiffest and most metabolically driven. Noise, ototoxic drugs, age and inflammation all take the top notes first for the same anatomical reason — and the top notes are the consonants, the high-frequency, low-energy, short parts of speech that carry most of the information in language. Vowels are loud and low and survive; the world does not go quiet, it goes blurry, words arriving with their edges filed off. That is sensorineural hearing loss: the sound arrives perfectly well and the machinery that should transduce it, or the nerve beyond it, has failed. Turning up the volume does not help, which is why shouting at someone with it makes them wince without a word becoming clearer. The signal climbs from the cochlear nerve to the cochlear nuclei of the medulla, then to the superiorAbove or toward the upper part of the body. olive, where the two ears are first compared for location — a sound on the left reaches the left ear microseconds sooner and slightly louder, because the head blocks it — then the inferiorBelow or toward the lower part of the body. colliculus of the midbrainThe upper portion of the brainstem involved in visual and auditory processing. (with a branch to the superior colliculus that turns your head), the medialToward the midline of the body geniculate nucleus of the thalamusThe brain’s relay center, sending sensory information to the cerebral cortex., and the primary auditory cortex in the temporal lobe, which reads pitch, loudness and location off the map. Beside it the auditory association area is where perception happens: whisper versus scream, your name in a crowded room. Damage the second and you can hear perfectly and understand nothing. Stina’s problem is at the other end of the chain. Her high-frequency dip points at the base of the cochlea and its hair cells, in a woman too young for the audiogram she has. The mechanism this course proposes is the one the anatomy predicts: chronic IL-1β and IL-6 acting on a microvascular bed with no margin for error, in a tissue that cannot replace what it loses. Be honest about its standing. Cochlear involvement in familial Mediterranean fever is a documented finding — published hearing evaluations in FMF patients from 2011 and 2013 are on the evidence page — but it is cohort-level evidence, no one has looked inside her cochlea, and “the same cytokines” is the case’s own reading, not a measurement. What is a measurement is the shape of the audiogram, and the shape says base, hair cells, permanent.

See it move: Scene 3 · The Organ of Corti · Scene 4 · Up the Brainstem · Scene 5 · The Audiogram

Watch · explore · think · check

5 scenes. Each one has a short animation or a slide, something to explore, a true/false spot-check of your thinking, and a quick check. Every scene gives you an evidence card for your board.

How to read the scenes

Animation (dark teal) — a short animated explainer, one idea each
Slide (dark teal) — a still to study: a micrograph, a diagram or a map
Explore (purple) — something to push on while you watch
Game (purple) — a quick challenge
Think (gold) — reason it out, then spot-check yourself with a few true/false questions; not graded
Check (gold) — a quick H5P that scores itself

Scene 1 of 5

Outer and Middle

A funnel, a drum, three bones, and a trick with pressure that adds no energy.

Animation · in production · 1 min 45 s

Twenty-Fold

The auricle funnels a wave down the canal; the drum moves; malleus, incus and stapes rock; a pressure gauge at the drum reads 1 and at the footplate reads about 20 as the force is concentrated onto a far smaller area. The auditory tube pops open on a swallow. Then three faults, each with a frequency bar dimming evenly across the whole range: wax in the canal, fluid behind the drum, a stapes fused to its window. A volume knob turns up and the bar recovers. Caption: conduction, and a loss that volume fixes.

Prefer the full lecture? The Fading Sound (original video on the site)

Explore · in production

Build the middle ear

An empty middle ear between a drum and a window, and three bones in a tray. Before any key, place them in order and name them, decide which is fixed to the drum and which sits in the oval window, and predict the pressure gain from the area ratio shown on screen. Then three patients — a swimmer with a blocked canal, a child with a cold and fluid behind the drum, a grandmother whose stapes has stiffened — and a frequency bar for each: shade what you think each one loses, then turn up the volume and predict whether it helps. The reveal names all three as conductive and shows why the bar dims evenly.

Think · not graded

The ossicles multiply pressure about twenty-fold without adding any energy, by concentrating the drum’s force onto the small footplate. A stapes fused to its window blocks that transfer and every frequency dims together. If a patient’s loss dimmed only the high frequencies, what does the evenness rule let you say about the middle ear before you have looked in it?

The true/false spot-check for this prompt is in production.

Check · Drag and Drop

Label the ear.

This self-scoring check is in production.

Evidence card 1

Add it to your evidence board

Her canals were clear, her drums intact and mobile, her tympanograms normal: nothing in the outer or middle ear — the conductive half of the chain — explains the loss.

Scene 2 of 5

Past the Oval Window

Three tubes in a snail shell, two fluids, and a membrane that sorts sound by place.

Animation · in production · 1 min 55 s

The Prism

The cochlea uncoils into a straight tube with three stacked channels; perilymph in the outer two, endolymph in the duct, the stria vascularis glowing along the outer wall. The stapes rocks; a traveling wave runs the basilar membrane; the round window bulges. A low tone peaks far along, near the wide floppy apex; a high tone peaks near the narrow stiff base; a chord peaks in three places at once. A piano keyboard wraps itself into the snail. Caption: 20,000 at the base, 20 at the apex, and the analysis is done before the brain sees anything.

Prefer the full lecture? The Fading Sound (original video on the site)

Explore · in production

Play the membrane

An uncoiled cochlea with a keyboard under it. Before any key, press a note and predict where along the membrane it will peak; press a higher one, a lower one, a chord. Then label the three scalae and the two windows, and drop the two fluids where they belong. A last slider dims the base of the membrane from the windows forward and asks which keys go silent first — and what a conversation sounds like when they do.

Think · not graded

The basilar membrane is narrow and stiff at the base and wide and floppy at the apex, so each frequency peaks at its own spot. Every traveling wave, whatever its pitch, has to pass the base to get anywhere. Which hair cells, then, get shaken by every sound you have ever heard — and what does that predict about which end of the map wears out first, under almost any insult?

The true/false spot-check for this prompt is in production.

Check · Summary

How sound becomes signal.

This self-scoring check is in production.

Evidence card 2

Add it to your evidence board

A loss at the high frequencies is a loss at the base of the cochlea, by the windows — the stretch of membrane every sound passes and the first stretch anything wears out.

Scene 3 of 5

The Organ of Corti

Bend toward the tallest and the channel opens — and the cell that hears is not the cell that fires.

Animation · in production · 2 min 00 s

Tallest to Shortest

A hair cell in close-up; stereocilia tallest to shortest, tethered tip to tip, embedded above in the tectorial membrane. The basilar membrane rises; the bundle bends toward the tallest; the tethers pull; channels open; K+ floods in from the endolymph; the cell depolarizes; glutamate drops onto a spiral ganglionA cluster of neuron cell bodies located in the peripheral nervous system (PNS). fiber, which fires. The membrane falls; the bundle bends the other way; the tethers slacken; the fiber quiets below its resting trickle. Pull back: one row of inner hair cells with the nerve fibers; three rows of outer cells twitching in time with the tone, sharpening the peak. Caption: the cell hears, the fiber fires, and neither of them grows back.

Prefer the full lecture? The Fading Sound (original video on the site)

Explore · in production

Bend the bundle

A hair cell with a bundle you drag. Before any key, predict which direction opens the channels, which ion comes in and from which fluid, and whether the hair cell or the ganglion fiber fires the action potentialA rapid, temporary electrical charge that travels along neurons, allowing signal transmission.; then drag and watch the trace. A second screen shows the three rows and the one row and asks which does the hearing and which does the sharpening. A last counter: fifteen thousand cells at birth, a slider for noise, drugs, years and inflammation — and a question answered before the reveal: what regrows?

Think · not graded

Taste cells are replaced every ten days, olfactory neurons for life, and cochlear hair cells never. All three are receptorA structure that detects stimuli. cells that hand a signal to a separate neuron. If you were a slow inflammatory process looking for a tissue where damage would accumulate rather than heal, which of the three would you choose — and which end of it?

The true/false spot-check for this prompt is in production.

Check · Single Choice

Why is sensorineural hearing loss from hair-cell damage permanent?

This self-scoring check is in production.

Evidence card 3

Add it to your evidence board

A receptor cell that does not fire, that hands its signal to a nerve, and that is never replaced: a loss here is a one-way door, and the door she walked through is at the base.

Scene 4 of 5

Up the Brainstem

Two ears compared in the brainstem, a map read in the temporal lobe — and the kind of deafness where you hear everything and understand nothing.

Animation · in production · 1 min 40 s

Where, Then What

A click on the left. It reaches the left ear microseconds sooner and slightly louder; both signals climb cranial nerve VIII to the cochlear nucleiClusters of neurons in the CNS responsible for processing information.; in the superior olive they are compared and a direction is computed; the inferior colliculus relays; a branch to the superior colliculus swings the head left; the medial geniculate nucleusThe control center of the cell that contains DNA and directs cellular activities. hands it to the primary auditory cortex, which reads pitch, loudness and location off the map; the association area next door names it — a dropped fork. Then the association area dims: the fork drops again, the sound arrives perfectly, and nothing is recognized. Caption: primary tells you a sound occurred; association tells you what it was.

Prefer the full lecture? The Special Senses and Cranial Nerves (original video on the site)

Explore · in production

Climb the ladder

A brainstem with six unlabeled rungs and a cortex with two doors. Before any key, stack the stops in order — spiral ganglion, cochlear nuclei, superior olive, inferior colliculus, medial geniculate, primary auditory cortex — and say which rung first compares the two ears. Then a sound-localization game: a click arrives at the two ears with a time difference you can read on screen; predict left or right before the head turns. A last patient hears a tuning fork perfectly and cannot say what it is: which door is shut?

Think · not graded

Sound location is computed in the brainstem by comparing the two ears for arrival time and loudness; the cochlea itself knows only pitch. Stina’s loss is symmetric. What would a one-sided cochlear loss do to her ability to tell where a sound came from — and why would a symmetric loss leave that ability alone while still ruining a restaurant?

The true/false spot-check for this prompt is in production.

Check · Mark the Words

Mark every stop on the road from cochlea to cortex. Leave the visual and vestibular stops unmarked.

This self-scoring check is in production.

Evidence card 4

Add it to your evidence board

Her loss is symmetric, which leaves the brainstem comparison nothing to compare — the fault is at the receptor end of the chain, where the audiogram already pointed.

Scene 5 of 5

The Audiogram

Conductive or sensorineural, and the shape that says base, hair cells, permanent.

Animation · in production · 2 min 00 s

Consonants First

An audiogram grid: frequency across, thresholdThe minimum voltage needed to trigger an action potential. down. A normal curve runs flat; a conductive loss drops the whole curve evenly with a gap between air and bone; a sensorineural loss keeps air and bone together and dips at the right-hand end. Stina’s curve draws itself: flat through the speech middle, sloping down at the high frequencies, both ears. A tuning fork on the mastoid, then at the canal — air better than bone; on the vertex — midline. A sentence plays with the high frequencies filtered out: the vowels survive, the consonants blur, a restaurant’s broadband roar swamps what is left. Last, the cochlear wall: the stria vascularis and its capillary bed with cytokine icons drifting past, and an honesty card: documented in FMF cohorts (2011, 2013); never looked at in her; the case’s own reading. Caption: the shape of a loss tells you where it happened.

Prefer the full lecture? The Fading Sound (original video on the site)

Explore · in production

Read the audiogram

Three blank audiograms and three patients you can only hear: one with wax in both ears, one with high-frequency loss, one with a one-sided dead cochlea. Before any key, play each a sentence and a tuning fork (mastoid, canal, vertex), then draw the curve you think each would produce and mark air and bone. The reveal overlays the real curves and asks the last question in one sentence: which of the three patients does turning up the television help, and which one does shouting only hurt?

Think · not graded

Her audiogram at 43 was called earlier than age explains, her reading glasses at 45 were on schedule, and both were filed under “age.” The evidence page says cochlear involvement in FMF is documented in cohorts and that no one has examined her cochlea. Write the one sentence that keeps both truths — what is measured and what is proposed — and say which word in it a clinician should underline.

The true/false spot-check for this prompt is in production.

Check · Drag the Words

Inflammation in the inner ear — kept honest.

This self-scoring check is in production.

Evidence card 5

Add it to your evidence board

Air beats bone, the drums are intact, and the dip is at the high frequencies: sensorineural, basal, permanent — in a woman too young for it, with a published cohort finding beside her and a mechanism the course proposes but has not measured.

Your evidence board

Every scene gave you an evidence card, and the chart adds more. Sort each card into the column it supports: A basal cochlear loss, early, where inflammation can reach, Neither on its own, or Ordinary age-related hearing loss, or a blocked ear. Some cards can honestly go in more than one place — that’s allowed, and the feedback tells you which cards decide the case.

Evidence board · drag and drop · in production

The sorting board for this chapter’s cards is being built. Until it arrives, sort your evidence cards on paper into the three columns above.

Your verdict

Time to decide. Look back at your bet, then build your verdict from statements that hold up — no writing needed.

Look back at your prediction

Consonants gone in restaurants, drums intact, air better than bone, a dip only at the high frequencies, at 43 — the reading that fits best is…

Find the one you chose at the top. Does the evidence support it, refute it, or revise it?

Wax or fluid — a blocked ear, fixed by cleaning it
Hair cells at the base of the cochlea, lost and not coming back
The auditory cortex has stopped understanding speech

Build your verdict · no writing

Choose the statement that holds in each set. The ones you keep become your argument.

This activity is in production.

The finding

Finding · the audiologist’s folder

The High Notes That Don’t Come Back

2018: consonants gone, birdsong gone, a ringing; drums intact, middle ears clear; air better than bone; a symmetric dip at the high frequencies, earlier than age explains. Chart entry: sensorineural loss at the base of the cochlea on cranial nerve VIII — hair cells that do not regrow, in a tissue with two fluids, a standing voltage and a single small blood supply. Documented in FMF cohorts; never examined in her; the mechanism is the case’s reading. Held open: the other half of the same nerve.

Next · Chapter 7

Balance, and Chart Clue #12

The sense you notice only when it fails shares a nerve and a fluid with the hearing that is failing, and it is quiet. Write that down precisely. Then put a face nerve, a cochlea and ten spared cables on one page and ask what moves them.

Continue to Chapter 7 →

Reliable information on rare diseases

NORD · NIH GARD · Orphanet · MedlinePlus Genetics: FMF · FMF & AID Global Association · Autoinflammatory Alliance · Global Genes · Amyloidosis Foundation

Stina has one rare disease. In the United States, about 1 in 10 people live with one of the more than 7,000 known rare diseases. These organizations are where patients, families and clinicians go for trustworthy information.

Hop to:

← Familial Mediterranean Fever — case home

All pages for Module 12 — The Special Senses

12.0 Module Overview
12.1 Two Nerves, One Neighborhood
12.2 Twelve Private Cables
12.3 The Chemical Senses
12.4 The Eye
12.5 The Retina
12.6 Sound Becomes Signal
12.7 Balance, and Chart Clue #12
12.8 Conclusion and Assessment
12.9 Evidence Behind the Case

List of terms

pressure
movement
head
channels
brainstem
temporal lobe
cells
conduction
base
cranial nerves
anatomy
physiology
energy
pharynx
temporal bone
cerebrospinal fluid
potassium
postcentral gyrus
mechanoreceptors
fact
liver
neurons
superior
inferior
midbrain
medial
thalamus
ganglion
action potential
receptor
nuclei
nucleus
threshold

12.6 Sound Becomes Signal

Read the chart

The story

I · Air to bone to fluid

II · Past the oval window

III · The organ of Corti, and what inflames quietly

Watch · explore · think · check

Outer and Middle

Twenty-Fold

Build the middle ear

Past the Oval Window

The Prism

Play the membrane

The Organ of Corti

Tallest to Shortest

Bend the bundle

Up the Brainstem

Where, Then What

Climb the ladder

The Audiogram

Consonants First

Read the audiogram

Your evidence board

Your verdict

The finding

The High Notes That Don’t Come Back

Balance, and Chart Clue #12

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List of terms