1Phys 1240: Sound and MusicLAST: resonance, work, energyTODAY: instruments:percussion, string, and windNEXT: more instrumentsREAD: Finish Chapter 3.Help sessions - find Chris/David!1st midterm: Thurs 22 (!) See WebCT2res.xx.Can sound really break glass?A)Maybe, if it is high enough pitchB)Maybe, if it is loud enoughC)Maybe, if the sound frequencymatches the resonantfrequency of the glassD)Not likely!Chapter 3Sources of sound:PercussionWindString(and others!E.g., what’s a synthesizer?)CT 3.1.1(Reading/vocabulary:)The following sound could be classified as…i. Originalii. Naturaliii. Transienta) i. onlyb) ii. onlyc) iii. only.d) ii., and iii.e) (some other combination)2CT 3.1.2The following instrument could be classified as?a) Percussionsb) Stringsc) Windsd) It deserves its own classificationbellsCT 3.2.1Which of the following is generally acharacteristic of percussion instruments?a) The sound produces a clear sensation ofpitchb) The larger the amplitude of the vibrationsthe higher pitched the soundc) The larger the surface area of the objectthe softer the soundd) The sound produced is transiente) More than one of theseCT 3.2.2What happens to the energy that was originallypresent in the vibration on a struck percussioninstrument?a) It is transferred into pure potential energywhich is then able to dissipateb) The force of gravity ultimately cancels outall the energyc) It is carried away by heat and soundd) It all turns to heat (sound is irrelevant, itdoes not carry away energy)e) There is no energy present as long as anobject vibrates steadilyCT 3.2.3This is a picture of a Marimba (closelyrelated to a Xylophone, also withwooden bars):What is the importance of the symmetry of the pipes?a) To get a full range of notesb) To complete the resonancec) To improve and clarify the soundd) Aestheticse) Some other reasonListen(It’s basically a visual trick!)3CT 3.2.4If I double the surface area of a percussioninstrument, (all other things being equal), whathappens to the loudness?a) It increasesb) It decreasesc) It remains the samed) Not enough informationWhat happens to the pitch?• It gets higher• It gets lower• It remains the same• Not enough information to decideCT 3.2.5Will the vibrations of a tuning fork diefaster if I hold it a little closer to the microphone?a) Yesb) Noc) Not enough informationWhat if I touch it to the desk?OctavesDoubling the frequency produces atone which is “the same” (sort of!) => It’s one octave higherSame NAME (e.g. middle C, go upby a factor of 2 in frequency,you’re back to C
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