tympanum

O thou philosophic Teufelsdrockh, that listenest while others only gabble, and with thy quick tympanum hearest the grass grow!

When the tympanum vibrates under the influence of the voice, the stylus acts as a pawl and turns a ratchet-wheel.

The tympanum T is that which is used for recording the sounds, and M is a mouthpiece, which is fixed to it for speaking purposes.

The other tympanum, T', reproduces the sounds; and E E is a branched ear-piece, conveying them to the two ears of the listener.

The air bladder therefore assists the ear of the catfish as the tympanum and its bones assist the ear of the higher animals.