Inside the system
19 notes in this shelf
Science
Plain-language explanations of the cochlea, auditory pathways, and current research models.
Latest in Science
Sorted by publish date.
- 01Jul 15, 2026
Why does my tinnitus squeal when I move my eyes?
Eye movement can rarely modulate tinnitus through somatosensory links in the brainstem. It is worth noting, and some symptoms need care. What to watch.
Read note → - 02Jul 15, 2026
Why does my tinnitus tone change when I cover my ear?
Covering one ear changes outside sound, body sound, and ear-canal resonance, so tinnitus may shift pitch or location for a moment. Know when to act now.
Read note → - 03May 22, 2026
Auditory brainstem response (ABR): the test that bypasses behavior
ABR uses scalp electrodes to record auditory nerve and brainstem responses to clicks. The standard test for newborns, retrocochlear lesions, and patients who can't respond behaviorally.
Read note → - 04May 22, 2026
The cochlear amplifier: outer hair cells as the mechanical pre-amp
Outer hair cells provide ~50 dB of mechanical amplification of basilar membrane motion. Their electromotility is the mechanism behind the cochlear amplifier.
Read note → - 05May 22, 2026
The endolymphatic potential: the +80 mV battery powering hearing
The cochlea maintains an unusual +80 mV potential in the endolymph, generated by the stria vascularis. This battery powers hair-cell transduction.
Read note → - 06May 22, 2026
Loudness discomfort level (LDL): the volume at which sound becomes painful
LDL is the lowest sound level at which a stimulus is judged uncomfortably loud. Standard hyperacusis assessment and the input to safe hearing-aid fitting.
Read note → - 07May 22, 2026
Olivocochlear efferent system: feedback control of the cochlea
Medial olivocochlear efferents from the brainstem suppress outer hair cell amplification, providing feedback control. Implications for hearing in noise and tinnitus.
Read note → - 08May 22, 2026
Otoacoustic emissions (OAE) test: how it detects outer hair cell function
OAEs are sounds the cochlea itself emits. The OAE test checks outer hair cell function, often catching damage before standard audiometry shows it.
Read note → - 09May 22, 2026
Speech-in-noise testing: why your audiogram can be normal but listening is hard
QuickSIN, BKB-SIN, HINT: the tests that quantify how well you understand speech against background noise. Why audiologists run them when audiograms look fine.
Read note → - 10May 22, 2026
Stria vascularis: the cochlea's metabolic engine
The stria vascularis maintains endolymph composition and the endocochlear potential. Its decline with age is a major contributor to presbycusis.
Read note → - 11May 22, 2026
Tonotopic map development: from birth to cortex
The cochlear-cortical tonotopic map develops in the first year of life under sensory experience. Sensitive periods, plasticity, and implications for cochlear implant outcomes.
Read note → - 12May 22, 2026
Cochlear traveling wave: von Bekesy and the basilar membrane
Sound enters the cochlea as a fluid wave that travels along the basilar membrane, peaking at a frequency-specific location. The mechanical basis of frequency selectivity.
Read note → - 13May 22, 2026
Tympanometry explained: what the pressure test measures and why
Tympanometry measures eardrum mobility under varying pressure. It is the standard test for middle-ear effusion, ossicular issues, and patulous eustachian tube. What the trace shapes mean.
Read note → - 14May 21, 2026
Auditory cortex and phantom sound: why your brain rings when nothing does
Tinnitus is generated centrally even when triggered peripherally. fMRI and MEG studies of the auditory cortex point to maladaptive plasticity as the dominant model.
Read note → - 15May 21, 2026
The dB scale explained: logarithms, dB-SPL, dB-HL, and dBA
Why doubling decibels does not double loudness. The four dB scales you'll see on audiograms, exposure regulations, and consumer products.
Read note → - 16May 21, 2026
Hidden hearing loss: when an audiogram looks normal but listening is hard
Cochlear synaptopathy damages the synapses between hair cells and auditory neurons before audiometric thresholds shift. Why this matters for tinnitus and what 'normal' audiograms miss.
Read note → - 17May 21, 2026
How the cochlea works: a tour from eardrum to neuron
Three windings, two fluid compartments, 16,000 hair cells, and one tonotopic map. The cochlea translated for non-anatomists.
Read note → - 18May 21, 2026
Outer vs inner hair cells: the two-cell choreography behind hearing
Inner hair cells signal to the brain. Outer hair cells amplify the cochlear traveling wave. Noise damage hits outer hair cells first, which is why noise-induced tinnitus starts so quietly.
Read note → - 19May 21, 2026
Why hearing loss causes ringing: the central-gain hypothesis
When the cochlea sends less signal, the brain's auditory pathway turns up its gain. That gain amplifies internal noise into perceptible ringing. The current dominant model explained.
Read note →