What is "barrel of the ear"

Barrel \Bar"rel\ (b[a^]r"r[e^]l), n.[OE. barel, F. baril, prob. fr. barre bar. Cf. Barricade.]

1. A round vessel or cask, of greater length than breadth, and bulging in the middle, made of staves bound with hoops, and having flat ends or heads; as, a cracker barrel. Sometimes applied to a similar cylindrical container made of metal, usually called a drum.

2. The quantity which constitutes a full barrel. This varies for different articles and also in different places for the same article, being regulated by custom or by law. A barrel of wine is 311/2 gallons; a barrel of flour is 196 pounds.

3. A solid drum, or a hollow cylinder or case; as, the barrel of a windlass; the barrel of a watch, within which the spring is coiled.

4. A metallic tube, as of a gun, from which a projectile is discharged.
   --Knight.

5. A jar. [Obs.]
   --1 Kings xvii. 12.

6. (Zo["o]l.) The hollow basal part of a feather.

   Barrel bulk (Com.), a measure equal to five cubic feet, used in estimating capacity, as of a vessel for freight.

   Barrel drain (Arch.), a drain in the form of a cylindrical tube.

   Barrel of a boiler, the cylindrical part of a boiler, containing the flues.

   Barrel of the ear (Anat.), the tympanum, or tympanic cavity.

   Barrel organ, an instrument for producing music by the action of a revolving cylinder.

   Barrel vault. See under Vault.