Page:An outline of English phonetics ... with 131 illustrations (IA cu31924027389505).pdf/28

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simple experiment. Take a short tube of wood or glass T, say 4 cm. long and 1 cm. in diameter, and tie on to one end of it a piece of thin indiarubber tubing I, of a somewhat larger diameter, say 3 cm., as shown in fig. 6. The tube of wood or glass is taken to represent the windpipe, and the indiarubber part the larynx. The space enclosed by the edge of the indiarubber E, E, represents the glottis. If we leave the indiarubber part in its natural position and blow through the tube, air passes out, making a slight hissing sound. This corresponds to breath. If we take hold of two opposite points of the edge of the indiarubber, E, E, and draw them apart so that two edges of the indiarubber come into contact along a straight line, we have a representation of the glottis in the position for voice, the two edges which are in contact representing the two vocal chords. Now, if we blow through the tube, the air in passing out causes the edges to vibrate and a kind: of musical sound is produced. This sound corresponds to voice.

48. Every speech sound contains either breath or voice, Those which contain breath are called breathed or voiceless sounds, and those which contain voice are called voiced sounds. Examples of breathed sounds are p, f; examples of voiced sounds are b, v. When we speak in a whisper, voice is replaced throughout by whisper, the breathed sounds remaining unaltered. It will not be necessary to deal further with whisper.

49. It does not require much practice for a person with a fairly good ear to be able to recognize by ear the difference between breathed and voiced sounds. The following well known tests may, however, sometimes be found useful. If breathed and voiced sounds are pronounced while the ears are stopped, a loud buzzing sound is heard in the latter case but not in the former. Again, if the throat be touched by the fingers, a distinct vibration is felt when voiced sounds are pronounced, but not otherwise. Thirdly, voiced sounds can be sung, while breathed sounds cannot. Compare in these ways p with ɑ, f with v.

*50. The presence or absence of voice may be observed experimentally in various ways. Thus it. may be heard very clearly by means of a stethoscope, or simply by applying a funnel to the outside of the larynx and connecting it by means of a tube to one or both ears.