Phys 1240: Sound and MusicLAST: strings and harmonicsTODAY: harmonics, perception &earsNEXT: perception and spectraReading: Lecture notes for Ch 8.Harmonics on a string! fn= n "v2LOnly certain wavelengths “fit”,=> only certain frequencies resonate = n* (the “fundamental” frequency)L! 440Hz! 2 * 440Hz! 3 * 440HzL 2L/3! 3 * 440Hzf=?L 2L/3! 3 * 440Hz! 1.5 * 440HzA string on an instrument plays anA (440 Hz) when plucked. If youput your finger down lightly, onethird of the way along the string,and then pluck the longer side,you are mostly likely to hear…A: 3*440HzB: (1/3)*440 HzC: 3/2 * 440 HzD: 2/3 * 440 HzE: Something entirely differentct.10.1.10bA string on an instrument plays anA (440 Hz) when plucked. If youput your finger down hard(pushing the string to the fret), onethird of the way along the string,and then pluck the longer side,you are mostly likely to hear…A: 3*440HzB: (1/3)*440 HzC: 3/2 * 440 HzD: 2/3 * 440 HzE: Something entirely differentct.10.1.10b2Electric guitars can have severalpickups to detect string motion.You can flip a switch to activatesingle pickups or combos.Which pickup would you activate tomake your music sound “crisper”(i.e. pick up more of the higherpitch frequencies?)A.B.C.D. Somecombo / nodiff10.1.10cLFletcher-Munson graphFrequency (in Hz)SIL (deciBels)100100010k0100Fletcher-Munson graphFrequency (in Hz)SIL (deciBels)100100010k0100500 phon100CT 6.6.3 Which will SEEM like a biggerincrease in loudness?A) Increasing by 50 dB, whilelistening to 50 Hz soundB) Increasing by 50 dB, whilelistening to 1000 Hz soundC) Both seem “equally moreloud”Fletcher-Munson graphFrequency (in Hz)SIL (deciBels)100100010k0100500 phon100CT 6.6.4Music is recorded at a loud concert.You play it at home, and turn downthe volume (reducing ALLfrequencies by the same # of dB)How will it sound?A) Same, just quieterB) Low frequencies will be over-emphasized (“bass-y”)C) Low frequencies will be under-emphasized (“treble-y”)Fletcher-Munson graphFrequency (in Hz)SIL (deciBels)100100010k0100500 phon100Fletcher-Munson graphFrequency (in Hz)SIL (deciBels)100100010k0100500 phon100CT 6.6.5Music is recorded at a soft concert.You play it at home, and crank thevolume (increasing ALL frequenciesby the same # of dB)How will it sound?A) Same, just louderB) Low frequencies will be over-emphasizedC) Low frequencies will be under-emphasizedFletcher-Munson graphMIDDLEOUTER INNERMiddle earCT 6.1.1Why have a middle ear?A) To provide an amplifier ofpressure wavesB) To better couple pressurewaves from “air” medium to“liquid” mediumC) To protect the inner ear fromextremely loud soundsD) To maintain the tympanicmembrane (eardrum) inproper equilibriumE) More than one of the aboveCT 6.1.1aThe eardrum is ~ 20 times larger than the ovalwindow.Assume force is same on either end of theconnecting bones (“ossicles”)The pressure on the oval window is…A) 20 times larger than on eardrumB) 20 times smaller than on eardrumC) 400 times larger than on eardrumD) 400 times smaller than on eardrumE)
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