The Collaborative International Dictionary of English v.0.48:

Auxetophone \Aux*e"to*phone\, n. [Gr. ? that may be increased +
   ? sound, voice.]
   A pneumatic reproducer for a phonograph, controlled by the
   recording stylus on the principle of the relay. It produces
   much clearer and louder tones than does the ordinary
   vibrating disk reproducer. [obsolescent]
   [Webster 1913 Suppl.]