The Collaborative International Dictionary of English v.0.48:

Speaking \Speak"ing\, a.
   1. Uttering speech; used for conveying speech; as, man is a
      speaking animal; a speaking tube.
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   2. Seeming to be capable of speech; hence, lifelike; as, a
      speaking likeness.
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   A speaking acquaintance, a slight acquaintance with a
      person, or one which merely permits the exchange of
      salutations and remarks on indifferent subjects.

   Speaking trumpet, an instrument somewhat resembling a
      trumpet, by which the sound of the human voice may be so
      intensified as to be conveyed to a great distance.

   Speaking tube, a tube for conveying speech, especially from
      one room to another at a distance.

   To be on speaking terms, to be slightly acquainted.
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The Collaborative International Dictionary of English v.0.48:

Trumpet \Trump"et\, n. [F. trompette, dim. of trompe. See
   Trump a trumpet.]
   1. (Mus.) A wind instrument of great antiquity, much used in
      war and military exercises, and of great value in the
      orchestra. In consists of a long metallic tube, curved
      (once or twice) into a convenient shape, and ending in a
      bell. Its scale in the lower octaves is limited to the
      first natural harmonics; but there are modern trumpets
      capable, by means of valves or pistons, of producing every
      tone within their compass, although at the expense of the
      true ringing quality of tone.
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            The trumpet's loud clangor
            Excites us to arms.                   --Dryden.
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   2. (Mil.) A trumpeter. --Clarendon.
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   3. One who praises, or propagates praise, or is the
      instrument of propagating it. --Shak.
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            That great politician was pleased to have the
            greatest wit of those times . . . to be the trumpet
            of his praises.                       --Dryden.
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   4. (Mach) A funnel, or short, fiaring pipe, used as a guide
      or conductor, as for yarn in a knitting machine.
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   Ear trumpet. See under Ear.

   Sea trumpet (Bot.), a great seaweed (Ecklonia buccinalis)
      of the Southern Ocean. It has a long, hollow stem,
      enlarging upwards, which may be made into a kind of
      trumpet, and is used for many purposes.

   Speaking trumpet, an instrument for conveying articulate
      sounds with increased force.

   Trumpet animalcule (Zool.), any infusorian belonging to
      Stentor and allied genera, in which the body is
      trumpet-shaped. See Stentor.

   Trumpet ash (Bot.), the trumpet creeper. [Eng.]

   Trumpet conch (Zool.), a trumpet shell, or triton.

   Trumpet creeper (Bot.), an American climbing plant (Tecoma
      radicans) bearing clusters of large red trumpet-shaped
      flowers; -- called also trumpet flower, and in England
      trumpet ash.

   Trumpet fish. (Zool.)
      (a) The bellows fish.
      (b) The fistularia.

   Trumpet flower. (Bot.)
      (a) The trumpet creeper; also, its blossom.
      (b) The trumpet honeysuckle.
      (c) A West Indian name for several plants with
          trumpet-shaped flowers.

   Trumpet fly (Zool.), a botfly.

   Trumpet honeysuckle (Bot.), a twining plant (Lonicera
      sempervirens) with red and yellow trumpet-shaped flowers;
      -- called also trumpet flower.

   Trumpet leaf (Bot.), a name of several plants of the genus
      Sarracenia.

   Trumpet major (Mil.), the chief trumpeter of a band or
      regiment.

   Trumpet marine (Mus.), a monochord, having a thick string,
      sounded with a bow, and stopped with the thumb so as to
      produce the harmonic tones; -- said to be the oldest bowed
      instrument known, and in form the archetype of all others.
      It probably owes its name to "its external resemblance to
      the large speaking trumpet used on board Italian vessels,
      which is of the same length and tapering shape." --Grove.

   Trumpet shell (Zool.), any species of large marine univalve
      shells belonging to Triton and allied genera. See
      Triton, 2.

   Trumpet tree. (Bot.) See Trumpetwood.
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WordNet (r) 3.0 (2006):

speaking trumpet
    n 1: a trumpet-shaped acoustic device to intensify and direct
         the human voice; formerly held to the ear by a hard-of-
         hearing person