ࡱ> 5@ bjbj22 "VXXDDDD44484dL5|0w<55"555777vvvvvvv$lyR{v97@799vDD55v<<<9D855v<9v<<u=2o|t55 ДJ49 q.uw00wrZ|;Z|\tDDDDt"Z|u7>#8,<O8$s8H777vvl!D<l!Hong Kong University of Science and Technology COMP685B: Computer Music Spring 2004 Midterm Examination Saturday 3 April, 09:30-11:30AM Student Name: key  Student ID:  Instructions: This is a closed-book, closed-notes examination. Check that you have all 6 pages (including this cover page). Answer all questions in the space provided. Rough work should be done on the back pages. PageScore2/183/214/245/126/25Total /100 All short-answer questions are 3 marks. 1) What is the frequency of the fundamental if the 4th harmonic is at 1000 Hz? Answer: 250 Hz 2) The spectrum of a tone shows a plot of what? a) frequency vs. time b) amplitude vs. time c) amplitude vs. harmonic number d) harmonic number vs. time e) An amplitude envelope Answer: C 3) A waveform with a period of 10 seconds has what frequency? Answer: 0.1 Hz 4) If a tone at 9000 Hz is above the Nyquist frequency and below the sample rate and it folds over to sound like 5000 Hz due to aliasing, what is the sample rate? Answer: 14,000 Hz 5) The following is a Csound header sr = 20000 kr = 200 ksmps = 10 nchnls = 2 What is wrong? Answer: ksmps should be 100 6) Why is windowing necessary in time-varying Fourier analysis? Answer: To smooth samples at the window endpoints: to correct for an inaccurate user-specified fundamental frequency, and avoid implied discontinuity. 7) In additive synthesis, what is added? (Select the answer that best answers the question.) a) Two or more musical instrument tones b) Harmonic sine waves scaled by amplitude envelopes c) Wavetables d) Spectral snapshots e) Frequency deviations of 40-100 harmonics Answer: B 8) What is wrong with the following Csound score? ;p1 p2 p3 p4 p5 ; amp freq atck decay i1 4000 440 .1 .2 e Answer: p2 and p3 must contain the start time and duration respectively. 9) Write a Csound tempo statement that keeps a steady tempo of 84 beats per minute for 10 beats and then suddenly changes to 104 beats per minute. Answer: t0 84 10 84 10 104 10) What is wrong with the following Csound orchestra statement? result oscili 4000,440,1 Answer: result is illegal variable name (should be aresult). 11) What are the approximately lowest and highest frequencies humans can normally hear? Answer: Lowest: 20 Hz; Highest: 10,000-20,000 Hz 12) If a tone is 4 octaves lower than a 1000 Hz tone, what will its frequency be? Answer: 62.5 Hz 13) In wavetable synthesis, how many waveform periods are normally stored in each wavetable? Answer: 1 14) What is wrong with the following Csound f-statement? f1 0 1000 10 1.0 .9 .8 .7 Answer: The wavetable has a table length of 1000, but it must be a power of 2, or a power of 2 plus 1 (e.g., 1024 or 1025). 15) If a Csound variable has the name gkamp, what type of variable is it? Answer: A global control-rate variable. 16) Why are fade-ins and fade-outs always necessary on amplitude envelopes? Answer: To avoid clicks. 17) When does vibrato become FM? Answer: When the vibrato rate is faster than 20 Hz (especially as the vibrato rate approaches the fundamental frequency). 18) If a simple FM instrument has a carrier frequency of 240 Hz and a modulator frequency of 360 Hz, what will be the fundamental frequency? Answer: 120 Hz 19) For a simple formant FM instrument with the carrier frequency set to the 5th harmonic, which sidebands will contribute to the amplitude of the 7th harmonic? Answer: The 2nd and the -12th. 20) If one sound is 10 times greater than another in amplitude, what is the decibel difference? Answer: 20 log10 10 = 20 dB 21) Is additive synthesis an effect? Why, or why not? Answer: No, because it generates a sound rather than modifying a sound. 22) If you want to remove hiss from a recording, which type of filter should you use? Answer: Low-pass. 23) Does the comb filter frequency determine the delay time or gain factor? Answer: Delay time 24) If someone makes a loud sound and they are 1750 meters away from you, how long will it take the sound to reach you? Answer: 5 seconds 25) Given a Schroeder reverberator with a reverb time of 2 seconds and the longest comb delay time of .04 seconds, what gain factor should be user for that comb filter? Answer: .001 = g2/.04 .001 = g50 .0011/50 = g g = .87096 26) [25 marks] Write a Csound orchestra and score to produce a 5-second 1000 Hz sine wave. Make its maximum amplitude 5000, with a .05-second fade-in and .1-second fade-out. Also add vibrato to your sine wave, where the vibrato rate decreases from 6 Hz to 3 Hz over the 5-second duration, and the vibrato width increases from 0% to 2% of the fundamental frequency over the 5-second duration. Answer: ;----------------------------------------------------------------- sr = 22050 kr = 2205 ksmps = 10 nchnls = 1 instr 1 imaxamp = p4 ifreq = p5 ; vibrato: 9 marks kvrate linseg 6, p3, 3 ; 3 marks kvwidth linseg 0, p3, .02*ifreq ; 3 marks avib oscili kvwidth, kvrate, 1 ; 3 marks ; sinewave: 10 marks aenv linseg 0,.05,imaxamp,p3-.15,imaxamp,.1,0 ; 5 marks asig oscili aenv, ifreq+avib, 1 ; 4 marks out asig ; 1 mark endin ;----------------------------------------------------------------- ; score: 6 marks f1 0 1025 10 1 ; 3 marks ; st dur amp freq i1 0 5 5000 1000 ; 3 marks end ;----------------------------------------------------------------- [Note: -1 mark for each additional mistake] PAGE  PAGE 1 379GIOSTiqrsty{ 嶭呅vjvh|CJPJnHtHhWG|hXCJPJnHtHh= gCJPJnHtHh\L{CJPJnHtH h5CJh756CJhX56CJ hX5CJjhXCJUmHnHu hMCJh7hhX hXCJ hXCJ hCJ h5CJ hX5CJ)/HIUi2 $$Ifa$ & F & F$a$ {]$ Z@@#$IfVDWD$^`#a$gdWG| $$Ifa$zkd$$IfTll0n] t04 laT {]$ Z@@#$IfVDWD$^`#a$gdWG| $$Ifa$zkd$$IfTll0n] t04 laT {]$ Z@@#$IfVDWD$^`#a$gdWG| $$Ifa$zkd@$$IfTll0n] t04 laT * , E F N T U V ] ߱pdYS hCJh\L{hCJaJhB*CJaJph#hh5B*CJ\aJphhhh5CJH*\aJh5CJ\aJ h= g5CJhh5CJhX5>*CJ h zdCJ h\L{CJh7CJPJnHtHhWG|CJPJnHo(tH hXCJhWG|hXCJPJnHtHhM7CJPJnHtH {]$ Z@@#$IfVDWD$^`#a$gdWG| $$Ifa$zkd$$IfTll0n] t04 laT {]$ Z@@#$IfVDWD$^`#a$gdWG| $$Ifa$zkd$$IfTll0n] t04 laT {]$ Z@@#$IfVDWD$^`#a$gdWG| $$Ifa$zkd $$IfTll0n] t04 laT E F N U V }}}}}}}}}}gdzkd$$IfTll0n] t04 laT] e      Y Z b h i j    ! E O ˹˹ڌzoiYh= gh= g5OJQJ\^J h= gCJh\L{h= gCJaJ#hh= g5B*CJ\aJphh= ghB*CJaJph hCJh\L{hCJaJh= gB*CJaJph#hh5B*CJ\aJphhh j5CJ\aJh= g5CJ\aJh5CJ\aJhh56CJ\aJ      Y Z b i j   ! E Q [ g s gd= ggdO P \ f s { | } ­¡zvdXMG hqCJh\L{hqCJaJhqB*CJaJph#hhq5B*CJ\aJphhqh}^O5CJ\aJhq5CJ\aJ h= gCJh\L{h= gCJaJh= gB*CJaJph)h= gh= gB*CJOJQJ^JaJph#hh= g5B*CJ\aJphh= gh= g5CJ\aJh= gh= g5OJQJ\^Jh= g5OJQJ\^J  ^ | } 9H_ RSgdqgd= g QRSXFG_`aiop͇vjv\hs9B*OJQJ^Jphhs9B*CJaJph!hs9hqB*OJQJ^Jph$hs9hqB*OJQJ\^Jphh}^O5CJ\aJhq5CJ\aJ hqCJh\L{hqCJaJhqB*CJaJph#hhq5B*CJ\aJphhqhq5OJQJ\^Jh= ghq5OJQJ\^J$F`ai)*|}/JKSgd|gdq ()*.Az|}/0IJK÷䑆ëّنëviveh|h|5OJQJ\^Jh= gh|5OJQJ\^Jh|5CJ\aJhs95CJ\aJh|hqB*CJaJphh|B*CJaJphhqB*CJaJph#hhq5B*CJ\aJphhqh}^O5CJ\aJhq5CJ\aJ hqCJh\L{hqCJaJ%KS=>?CDEFGHIij}ŵű֦ű֦ű֓}śśśśű֦}hs95CJ\aJh|hM7CJaJh|CJaJh}^O5CJ\aJh|h|CJaJh|hs9h|5OJQJ\^Jh|5CJ\aJ h|CJh\L{h|CJaJh|B*CJaJph#hh|5B*CJ\aJph,>?EFG  (gd|(.46z|  $'()+-LM_`a̺||̺k_|hs9B*CJaJph hM7hM7B*CJH*aJphhs95CJ\aJh|h|CJaJh\L{h|CJaJ hM7hM7B*CJH*aJphhM7B*CJaJph#hh|5B*CJ\aJphh|h|5CJ\aJhM7hM75CJH*\aJh}^O5CJ\aJhM75CJ\aJ%()`ai cdlxygd}AgdM7gd|ai :Qacdlvwxyz{ʿʿʿn#hhM75B*CJ\aJphhM7h}^O5CJ\aJh|hM75CJ\aJh75CJ\aJh|5CJ\aJhs95CJ\aJh|h|CJaJh\L{h|CJaJh|B*CJaJphhM7B*CJaJph#hh|5B*CJ\aJph(),5FQgt⺨}}qf`UUUhbt5CJ\aJ hCJh|hM7CJaJh7B*CJaJphhM7B*CJH*aJph hM7hM7B*CJH*aJphhM7B*CJaJph#hhM75B*CJ\aJphhM7h}Ah}A5CJ\aJh}A5CJ\aJhs95CJ\aJhM75CJ\aJhM7CJaJh\L{hM7CJaJ!vw+P}4Sagdbtgd}Agd|gdM7uvw*+AEFrs`a²¤tcP$h}AhbtB*OJQJ\^Jph!h}AhbtB*OJQJ^Jph!h}Ah}AB*OJQJ^Jph!h}Ah~B*OJQJ^JphhbtB*OJQJ^Jphh}AB*OJQJ^JphhbtB*OJQJ\^Jph$h}Ah}AB*OJQJ\^Jph h}Ah}AB*CJ\aJphh}Ah}A5CJ\aJhbt5CJ\aJZ_`akp̹}yhXh/h/0JmHnHuh h0Jjh0JUhP5>*CJhbtB*CJOJQJaJph%hbthbtB*CJOJQJaJph!h}Ah}AB*OJQJ^JphhbtB*OJQJ\^Jph$h}AhbtB*OJQJ\^Jph"`ah]h &`#$gdgd\L{gdbt 1h/ =!"#$%$$If!vh55]#v#v]:V ll t055]4T$$If!vh55]#v#v]:V ll t055]4T$$If!vh55]#v#v]:V ll t055]4T$$If!vh55]#v#v]:V ll t055]4T$$If!vh55]#v#v]:V ll t055]4T$$If!vh55]#v#v]:V ll t055]4T$$If!vh55]#v#v]:V ll t055]4T<@< NormalPJ_HmH sH tH DA@D Default Paragraph FontVi@V  Table Normal :V 44 la (k(No List e@ HTML Preformatted7 2( Px 4 #\'*.25@9OJPJQJ^JnHtH4@4 Header  !@O@ Code ^CJOJQJ^JaJVO"V question_part ^5CJOJQJ^JaJLO2L question ^5CJOJQJ^JaJ4 @B4 Footer  !.)@Q. Page NumberV/HIUi2EFNUV YZbij  !EQ[gs^|}9H_ RSF`ai ) * | } / J K S    > ? E F G  ()`ai cdlxyvw+P}4Sa`a000000000000000 0 0 000( 0( 0, 0( 0, 0 0 0 0 0 0 0 0 0( ( 0, 00p0p0@0@0@0@000000000p@00@00@0@0@0@00@0@0@0@0000p00p0@0@00@00@0@0000@00@0@0@0@0@0p@0@0@0@00@0@0@0@0@0@0@0@000@00000@0@00@00@0@00@00@0@00@00@0@0000@0@00@00@0@0@0@00@0@00@00@0@0000p0@0@00@00@0@00@00@0@00@00@0@00@000@0@00@00@0@00@00@0@0@0@00@0@0000000p@0@00000p0p00p00000000000p0p0p00@0@0p@0@00000@0@0@0@0@0@006c00EFNUV YZbij  !|}_ RS`ai ) * | } J K S    > ? E G  ()`ai cdlxyvw+P}4Sa`O9008M900M900M900M900M900My00My00My00Oy00Oy00Oy00My00Oy00My00Oy00My00My00My00My00Oy0 0My0 0My0 0My00My00Oy0 0My0 0My0 0Oy00My00Oy0 0My0 0My0 0Oy00My00O90#0My0 0My0 0My0 0My00My00Oy0)0My0*0My0)0My0 0My0 0My00My00Oy0 0My0 0Oy0)0Oy00Oy0)0My0 0My0 0Oy00My00Oy00My00My00Oy00My00Oy00My00My00Oy00My00Oy00My00My00Oy00Oy0)0My0 0My0 0Oy00My00Oy00My00My00My00My00Oy00My00My00Oy00My00Oy00My00My00Oy00Oy00Oy00My00My00Oy00My00Oy00My00My00Oy00My00Oy00My00My00Oy00My00Oy00My00My00Oy00My00Oy00My00My00Oy00My00Oy00My00My00Oy00My00Oy00My00My00My00My00Oy00My00My00My00My00Oy00Oy00My00O900My0 0My0 0M900Oy0)0M9000M900M900O900O900O900M900M900M900O900,M900M900M900My000R$  ] O Ka !#%&() ("$'* !!8@f(  bB  c $g ?"bB  c $g ?"B S  ?' (t5 6t |4 { 8*urn:schemas-microsoft-com:office:smarttagstime=*urn:schemas-microsoft-com:office:smarttags PlaceType=*urn:schemas-microsoft-com:office:smarttags PlaceName9*urn:schemas-microsoft-com:office:smarttagsplace 309HourMinuteFHRT\ahn^cGMio < C    !+1PW}<?[`3333333333333333333333333333333333333333333ITiF[\hGa0 K wquanquanquanquanquanquanquanquanhorner cherryvalley| Djw u5! Z,U )ЦAv)9 ,:_!v~!4@)r}z3aAO4޹ag5GFra޲H$Q<h.\ahl.y0Th^`OJQJo(hHh^`OJQJ^Jo(hHohpp^p`OJQJo(hHh@ @ ^@ `OJQJo(hHh^`OJQJ^Jo(hHoh^`OJQJo(hHh^`OJQJo(hHh^`OJQJ^Jo(hHohPP^P`OJQJo(hH ^` OJQJo(hHl ^` OJQJo(hHn ^` OJQJo(hHu`  ` ^` ` OJQJo(hHl@  @ ^@ ` OJQJo(hHn   ^ ` OJQJo(hHu ^` OJQJo(hHl ^` OJQJo(hHn ^` OJQJo(hHuh^`OJQJo(hHh^`OJQJ^Jo(hHohpp^p`OJQJo(hHh@ @ ^@ `OJQJo(hHh^`OJQJ^Jo(hHoh^`OJQJo(hHh^`OJQJo(hHh^`OJQJ^Jo(hHohPP^P`OJQJo(hHh ^`o(hH)h^`OJQJ^Jo(hHohpp^p`OJQJo(hHh@ @ ^@ `OJQJo(hHh^`OJQJ^Jo(hHoh^`OJQJo(hHh^`OJQJo(hHh^`OJQJ^Jo(hHohPP^P`OJQJo(hH@h1h^h`.0^`0OJPJQJ^J) ^`hH. pLp^p`LhH. @ @ ^@ `hH. ^`hH. L^`LhH. ^`hH. ^`hH. PLP^P`LhH.0^`0o() ^` OJQJo(hHl  ^` hH.  ^` hH. `  ` ^` ` hH0 @  @ ^@ ` hH.    ^ ` hH.  ^` hH0  ^` hH.^`o(. ^`hH. pLp^p`LhH. @ @ ^@ `hH. ^`hH. L^`LhH. ^`hH. ^`hH. PLP^P`LhH.^`o() ^`hH. pLp^p`LhH. @ @ ^@ `hH. ^`hH. L^`LhH. ^`hH. ^`hH. PLP^P`LhH.^`o(. ( (^(` hH0  ^` hH.  ^` hH.    ^ ` hH0    ^ ` hH.  ^` hH. h h^h` hH0 H H^H` hH.\^`\B*OJQJo(phhHH\H^H`\B*OJQJo(phhH\^`\OJQJo(hHu\^`\OJQJo(hHl4\4^4`\OJQJo(hHn \ ^ `\OJQJo(hHu| \| ^| `\OJQJo(hHl \ ^ `\OJQJo(hHn\^`\OJQJo(hHu0^`0o()  ^` hH0  ^` hH.  ^` hH. `  ` ^` ` hH0 @  @ ^@ ` hH.    ^ ` hH.  ^` hH0  ^` hH.h^`OJQJo(hHh^`OJQJ^Jo(hHohpp^p`OJQJo(hHh@ @ ^@ `OJQJo(hHh^`OJQJ^Jo(hHoh^`OJQJo(hHh^`OJQJo(hHh^`OJQJ^Jo(hHohPP^P`OJQJo(hHh^`OJQJo(hHh^`OJQJ^Jo(hHohpp^p`OJQJo(hHh@ @ ^@ `OJQJo(hHh^`OJQJ^Jo(hHoh^`OJQJo(hHh^`OJQJo(hHh^`OJQJ^Jo(hHohPP^P`OJQJo(hHh0^`0OJPJQJ^J)h 88^8`hH.h L^`LhH.h   ^ `hH.h   ^ `hH.h xLx^x`LhH.h HH^H`hH.h ^`hH.h L^`LhH.808^8`0o() ^`hH. pLp^p`LhH. @ @ ^@ `hH. ^`hH. L^`LhH. ^`hH. ^`hH. PLP^P`LhH.hh^h`o()  ^` hH0  ^` hH.  ^` hH. `  ` ^` ` hH0 @  @ ^@ ` hH.    ^ ` hH.  ^` hH0  ^` hH.h808^8`0o() ^`hH. pLp^p`LhH. @ @ ^@ `hH. ^`hH. L^`LhH. ^`hH. ^`hH. PLP^P`LhH.^`o() ^`hH. pLp^p`LhH. @ @ ^@ `hH. ^`hH. L^`LhH. ^`hH. ^`hH. PLP^P`LhH.h^`OJQJo(hHh^`OJQJ^Jo(hHohpp^p`OJQJo(hHh@ @ ^@ `OJQJo(hHh^`OJQJ^Jo(hHoh^`OJQJo(hHh^`OJQJo(hHh^`OJQJ^Jo(hHohPP^P`OJQJo(hHAA`j4@) O4!$Q:_!l9z3wag5yu5! ,U 0.\GFH`j b@h1h^h`.                                    8                                   J&        ZIk                                 8                         &/                          q[PVfPVf21q27#V~0J#(-s9}A}^OQS[Q7\ zd= g j[jh~jEmbt\L{WG|="}`^}#LPX/HMM7]<>h~$)-"i-r\BG,Pr8|H2@`@Unknown Gz Times New Roman5Symbol3& z ArialC .PMingLiUe0}fԚ?5 z Courier NewQTimes New Roman Bold;SimSun[SO71 Courier;Wingdings"hFfcz7W '7W 'Y24d 3QH(?0J#.Hong Kong University of Science and Technologycslcwhorner\               Oh+'0   0< X d p |/Hong Kong University of Science and Technology1ongcslcwonslcslc Normal.dotnhornerd7rnMicrosoft Word 10.0@2~@m @tR,@@7W՜.+,D՜.+,` hp  HKUSTi' A /Hong Kong University of Science and Technology TitlehH <T\_AdHocReviewCycleID_EmailSubject _AuthorEmail_AuthorEmailDisplayName_PreviousAdHocReviewCycleID_ReviewingToolsShownOnceb>~ midterm examlsShorner@cs.ust.hkownAndrew Hornerhkg.nndr  !"#$%&'()*+-./012356789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrtuvwxyz|}~Root Entry FdJData ,1Table4|WordDocument"VSummaryInformation(sDocumentSummaryInformation8{CompObjj  FMicrosoft Word Document MSWordDocWord.Document.89q