A stimulus enters
The vagus and phrenic nerves, together with sympathetic fibres, can carry signals from the chest and abdomen into the reflex circuit.
BREATH · REFLEX · SOUND
A breath hits a gate.
A hiccup begins with an involuntary inspiratory contraction. Air moves towards the lungs, then a sudden laryngeal closure brakes it: “hic”.
35 ms
In approximately 35 milliseconds, inspiratory muscle contraction is followed by the classically described glottic closure.
DIAPHRAGM
GLOTTIS
air moves
the gate closes
01 · CHRONOGRAPH
Draw a “hic” in milliseconds.
Choose the rhythm and the gap between contraction and gate closure. The chronograph produces no sound and does not try to trigger an episode; it only makes the sequence visible.
Interval between contractions5.0 s
“Hic” window35 ms
At 12 per minute, contractions are 5.0 seconds apart.
Reading model. The physiological arc is real; the drawing simplifies duration and amplitude to separate events.
interval = 60 ÷ rhythm
02 · MEASURE A REAL EPISODE
Count without causing anything.
If you are already hiccupping, sit comfortably and start the timer. Press once for each “hic”; at the end you will see an approximate per-minute rhythm.
Safety boundary: do not try to induce hiccups, hold your breath or use manoeuvres that cause discomfort. If hiccups last more than 48 hours or affect breathing, sleep or eating, ask a clinician for advice.
30.0seconds
Timer ready.
Hiccups counted0Your rhythm will appear when it ends.
This measurement is not diagnostic. A short episode can vary from one “hic” to the next.
03 · THE REFLEX ARC
The diaphragm presses the accelerator. The larynx presses the brake.
The diaphragm contracts
Inspiratory muscles start a sudden inward movement. Air is pulled forward before the reflex closes.
The gate closes
In the classic description, the glottis closes shortly after contraction. Stopped air makes the sharp sound.
04 · THE NUMBER AND THE PUZZLE
The “hic” is fast. The full explanation is still open.
4–60 / min
Review literature describes a wide rate of 4 to 60 hiccups per minute. At 4 per minute, an idealised interval is 15 seconds; at 60 per minute, 1 second.
The exact structure that produces the sound is debated: the classic account points to the glottis, while a modern fluoroscopic study reopened the glottis–epiglottis question.Scientific note: involuntary diaphragm contraction and the reflex arc are well described. The idea that hiccups have a clear evolutionary purpose remains a hypothesis, not a settled conclusion.
SOURCES
What is firm, and what stays open.
- 01Howes (2012), Hiccups: a new explanation for the mysterious reflex.PubMed / PMC ↗
- 02Fass et al. (1997), Stimulus and site specific induction of hiccups in the oesophagus of normal subjects.PubMed / PMC ↗
- 03Seifi & Fox (2022), What puts the “hic” into hiccups?PubMed / PMC ↗
- 04Stacey & Bassett (2024), Hiccup Relief Using Active Prolonged Inspiration.PubMed / PMC ↗