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Show I Fireside Science By Reviuom Suttoo CeprrlgBt. llll N. T. gjvealag Werl4. Frees PsMlsalag Oa. ' MUSICAL SOUNDS. Irregular sound waves, caused by separate and distinct dlsturtmaces In the air. produce tha sensation of noise. If a succession of regular and rhythmic sound waves are produced by a vibrating object, such aa a violin string, the resulting brain sensation, as the wnvea beat upon tha lrum of the ear. la music Vibrating a etring slowly produces long waves, causing soft, low sounds low tn ths sense of pitch. The more rapid the vlbrationa tha more rapid the sound wavea and the higher the pitch. In etringed Instruments ths vlbrationa are controlled by tightening tighten-ing tha strings. Ire pianoa nd pipe organs, long sound wayes and resulting result-ing low no tee come from long strings and ptpes, whereas short waves, causing caus-ing high notes, coma from short strings and pipes. Basically there are only tow kinds of musical Instruments: (a Where air waves ve started ty vibrating airings, aa In vlotine, poo. harpe, bnJoa aad guitars. -ntha violin, the vibrations of tha strings are produced with a bow; In the piano, with a hammer; In harpe. ban-Joa ban-Joa and gut tare, by plucking the strings with ths fingers. bl Where air wavea are started by vibrating rods, .as In the aylophone and tuning forks. The longer the rods, the lower ths vibrations and tha lower the pitch. c) Where vibrations are etarted In the air Itself, aa In wind Instruments. In wind Instruments, ths air In the tubes Is caused to vibrate along the tube, whereas la at ringed instruments the direction of tha vlbrationa la across ths strings. This claas Includes In-cludes tha pipe organ, fife, flute, piccolo, pic-colo, bugle, cornet and trombone. d) Where the air wavee are produced pro-duced by vibrating membranes, aa tn tha drum, phonograph, gong, bell and human vocal corda. In a drum, there are two membranes, with air between. When one la struck, ths Inside sir starts vibrations In ths other membranes, mem-branes, so ths "mosio of tha drum cornea from ths una truck membrane. Mora wonderful than all other musical Instruments la the human voice. A pair of membranes, the vocal cords, may be stretched to vibrate alowly or loosely st will, producing pro-ducing a series) of sound wavea. The air from tha lunge, naasing aver these cords. Is est m vibration the result being noise, speech or music. It Is a self-tuning Instrument. The throat, nose and mouth act aa resonators reso-nators to reinforce tha vlbrationa. In woman and children the vocal corda are shorter than la men, giving taem a higher pftch. . . At the last meeting of the American Ameri-can Physical aoclaty, held In Pasadena. Pasa-dena. May a last. Profaaaor S. H. Anderson An-derson of ths University of Wsshlng-ton Wsshlng-ton demonstrated that ths formula followed (y manufacturers of stringed Instruments for vibrations of strtaga ! when sx cited by Impact (aa tn pianoa) la not quite correct. All ? ilanoa are now eonatructed accord-ngr accord-ngr to this formula originally put forth by U elm holts in ll.S, hence all contain a alight element of discord. The correct ton In the formula for vibrating vi-brating et rings when- ths vibrations are excited by ham mere will ultimately ulti-mately lead to purer tones. At this meeting Professor Vsra O. Knudsen of the University of California Cali-fornia reported the reeuhe of -a aeries of experiments to teat the auality of speech In auditoriums. It waa found that ft per cent ef the information obtained ob-tained by persona sitting near the epeeker cornea from lip reading: that auditors bear much more distinctly whan ths auditorium Is crowded; that vowel sound are seldom mfsuT4e-stood: mfsuT4e-stood: that the greateet difficulty lies witk the con sonants, aspeclalty with ng. a. v and th. Persons Interested hi the eonstrne-tien eonstrne-tien of musical Inatrumente or audt-toriuma audt-toriuma can obtain cooles of the, papera by communicating with ths authors. |