THE PHYSIOLOGY OF VOICE AND THE PHONOGRAPH.

New Zealand Times, Volume XXXIII, Issue 5378, 22 June 1878, Page 2 (Supplement)

THE PHYSIOLOGY OF VOICE AND THE PHONOGRAPH.

(From the Lancet.) The years 1877 and 1873 will be noted in the annals of science for the great additions which have been made to our knowledge of accoustics, and especially to the physiology of speech. Hitherto all attempts to construct a musical instrument capable of imitating the human voice have been so far failures that the idea was very generally held that the sounds peculiar to the voice of man were producible only by means of the human larynx and the human mouth. Edison’s phonograph, however, has revolutionised our ideas on that point, for in it we are confronted with the phenomenon of a machine, made entirely of metal and paper, emitting articulate words in tone and measure exactly resembling those of the original speaker. The human quality of the words emitted by Edison's phonograph is calculated to astonish and appal those who hear it for the first time, and the extreme simplicity of the mechanism adds greatly to our wonder at the result. The phonograph is formed of a receiving drum, a recording cylinder, and a transmitting drum. The receiving drum consists of a disc of thin metal, fitted into the thin end of a short conical tube. This disc has a blunt needle fastened to its centre, and this needle can bo made (with each vibration of the disc) to impinge on the recording cylinder. The necessary vibrations of the receiving drum are caused by speaking Joudly 'and distinctly down the conical tube of which it forms the end.- The recording cylinder is made of brass, and is about 4in. in diameter. It has a revolving and a horizontal motion, and is marked on the surface by a spiral groove, the thread of which passes exactly opposite the needle of

the receiving ' drum. When it is desired to make a record of a sound or a speech the recording cylinder is covered with a thin sheet of tinfoil, which is readily indented by the slightest movement of the needle of the disc of the receiving dram which impinges upon it, each dent in- the tinfoil, sinking into the groove of the cylinder. The cylinder is set in motion, and at the same time some one speaks loudly and distinctly into the tube of the receiving drum, thereby causing the drum to vibrate in response to each wave of sound. As a result of this we see the surface of the tinfoil marked with a spiral line of tiny'indentations, which have been made by the needle of the receiving drum, the characters of the indentations varying remarkably with the pitch and character of the sounds which had produced them. Tims the record is made by the production of inequalities on the surface of a sheet of tinfoil by means of a needle attached to a vibrating disc. These inequalities are capable of causing in. the transmitting drum vibrations exactly similar to those to which they owe their origins The transmitter consists of a paper drum-head fixed in a circular frame. In front of this drum-head, anaattached to its frame, is a steel spring, the end of which, just opposite the centre of the drumhead, is furnished on one side with a needle, which can be made to impinge on the spiral groove of the cylinder, while from the other side a silk thread attaches it to the centre of the drum-head, the thread being sufficiently taut to keep the drum-head slightly convex. The cylinder being brought back to zero, and the needle of the transmitter being made accurately to impinge upon it, we hear, when the cylinder is made to rotate, the sound produced by the vibrations of the drum-head as the inequalities of the tinfoil travel over the end of its spring needle. This sound is almost indistinguishable from the human voice. By means of a water tympanum, the horizontal vibrations of the drum-head can be made to move a pen vertically, and we are thus enabled to get a tracing showing the force and duration of each vibration. Such an arrangement is called a phonautograph. The phonograph and the phonautograph present us, as it wore, with the ground plan and section of the waves which produce articulate speech. The complicated mechanism with which we speak—a mechanism the perfection of which is ever a source of wonder—is not, it must be remembered, a simple accoustic instrument. Its various parts have more than one function, and these functions, so intimately connected with nutrition and respiration, are each of them more essential for the life of the individual than speech. As regards speech itself, it is wonderful how little seems to be absolutely necessary for its complete performance. The utterances of ventriloquists have made it highly probable that very perfect articulation is producible without any appreciable movement of the lips or tongue, and experiments made for us by disease and surgery have confirmed these surmises. Operations for removal of the tongue have proved that a man can talk fairly web without this organ : loss of the epiglottis causes only a slight alteration of the character of the voice ; one vocal chord (in cases where one is completely ulcerated away) seems capable of producing sufficient vibration for the purposes of phonation, and where both are removed the ary-epiglottic folds, as Dr. Yeo and Mr. Lister have lately shown, seem cTapable of, in some sort, supplying their place ; or, as Dr. Emilia has demonstrated, the functions of phonation can be performed by an articial reed placed in the larynx, the sound of which is capable of being moulded into articulate speech by the cavities of the mouth and nose. Lastly, the phonograph shows us that the majority at least of articulate sounds are producible without the aid of the pecudar resounding cavities of the mouth and nose ; and some experiments conducted by Professor Jenkin and Mr, Ewing, which arc foreshadowed in last week’s Nature, seem to indicate that Helmholt’s theory, that the vowel sounds are due to the prominence of notes of absolutely definite pitch, is not tenable. The pitch of the sounds emitted by the phonograph varies with the rate of its rotation, and Messrs. Jenkin and Ewing have found that the character of the vowel sounds is accurately maintained, no matter how quickly the cylinder of the instrument be made to revolve.