,transcrib]'s ,note3 ,italic text is enclos$ 9 und]scores2 boldface text on ! la/ page ( ! book is enclos$ 9 equals signs4 ,o!r notes w be f\nd aft] ! footnotes4 ,,univ]sity ,,( ,,ill9ois ,,bullet9 ,,issu$ ,,weekly ,vol4 ,,xi ,,m>* #af1 #aiad ,no4 #bi ,ent]$ z second-class matt] ,dec4 #aa1 #aiab1 at ! ,po/ ,(fice at ,urbana1 ,ill41 "u ! ,act ( ,aug4 #bd1 #aiab4 ,,ac\/ics ,,( ,,auditoriums ,,by ,f4 ,r4 ,,watson ,illu/ration3 ,,univ]sity ,,( ,,ill9ois4 ,,*>t]$ #ahfg4 ,,bullet9 ,no4 #gc ,,eng9e]+ ,,exp]im5t ,,/ation ,,publi%$ ,,by ,,! ,,univ]sity ,,( ,,ill9ois1 ,,urbana ,,price3 ,,tw5ty ,,c5ts ,,european ,,ag5t ,,*apman ,,& ,,hall1 ,,ltd41 ,,london ,! ,eng9e]+ ,exp]im5t ,/ation 0 e/abli%$ by act ( ! ,bo>d ( ,tru/ees1 ,decemb] #h1 #aijc4 ,x is ! purpose ( ! ,/ation to c>ry on inve/igations along v>i\s l9es ( eng9e]+ & to /udy problems ( importance to pr(essional eng9e]s & to ! manufactur+1 railway1 m9+1 con/ructional1 & indu/rial int]e/s ( ! ,/ate4 ,! control ( ! ,eng9e]+ ,exp]im5t ,/ation is ve/$ 9 ! heads ( ! sev]al dep>tm5ts ( ! ,college ( ,eng9e]+4 ,^! con/itute ! ,/ation ,/aff &1 ) ! ,director1 det]m9e ! "* ( ! inve/igations to be und]tak54 ,! "w is c>ri$ on "u ! sup]vision ( ! ,/aff1 sometimes by rese>* fell[s z graduate "w1 sometimes by memb]s ( ! in/ructional /aff ( ! ,college ( ,eng9e]+1 b m frequ5tly by inve/igators belong+ to ! ,/ation corps4 ,! results ( ^! inve/igations are publi%$ 9 ! =m ( bullet9s1 :i* record mo/ly ! exp]im5ts ( ! ,/ation's own /aff ( inve/igators4 ,!re w also be issu$ f "t to "t 9 ! =m ( circul>s1 compilations giv+ ! results ( ! exp]im5ts ( eng9e]s1 indu/rial works1 te*nical in/itutions1 & gov]nm5tal te/+ dep>tm5ts4 ,! volume & numb] at ! top ( ! title page ( ! cov] are m]ely arbitr>y numb]s & ref] to ! g5]al publications ( ! ,univ]sity ( ,ill9ois2 ei!r above ! title or bel[ ! seal is giv5 ! numb] ( ,eng9e]+ ,exp]im5t ,/ation bullet9 or circul>1 :i* %\ld be us$ 9 ref]r+ to ^! publications4 ,= copies ( bullet9s1 circul>s1 or o!r in=mation address ! ,eng9e]+ ,exp]im5t ,/ation1 ,urbana1 ,ill9ois4 ,illu/ration3 ,,fig4 #a4 ,,auditorium1 ,,univ]sity ,,( ,,ill9ois4 ,,ac\/ics ,,( ,,auditoriums ,,an ,,inve/igation ,,( ,,! ,,ac\/ical ,,prop]ties ,,( ,,! ,,auditorium ,,at ,,! ,,univ]sity ,,( ,,ill9ois4 ,i4 ,,introduction4 ,mu* conc]n has aris5 9 late ye>s 9 ! m9ds ( ar*itects because ( ! faulty ac\/ics t exi/ 9 _m auditoriums4 ,! preval5ce ( e*oes & rev]b]ations ) ! consequ5t difficulty 9 he>+ & und]/&+ on ! "p ( ! auditor defeats ! purpose ( ! auditorium & dim9i%es its value4 ,! ,auditorium at ! ,univ]sity ( ,ill9ois pres5ts su* a case4 ,! build+ is %ap$ ne>ly l a hemisph]e1 ) sev]al l>ge ar*es & recesses to break up ! regul>ity ( its inn] surface4 ,! orig9al plans ( ! ar*itect 7 curtail$ because ( insuffici5t money appropriat$ = ! con/ruction4 ,! int]ior ( ! hall1 !re=e1 0 built absolutely pla9 ) almo/ no break+ up ( ! l>ge1 smoo? wall surfaces2 &1 at fir/1 !re 7 no furni%+s except ! seats & ! cocoa matt+ 9 ! aisles4 ,! ac\/ical prop]ties prov$ to be v unsatisfactory4 ,a rev]b]ation or undue prolongation ( ! s\nd exi/$1 & 9 addition1 because ( ! l>ge size ( ! room & ! =m & position ( ! walls1 e*oes 7 set up4 ,if an obs]v] /ood on ! plat=m & clapp$ 8 h&s1 a v]itable *aos ( s\nd result$4 ,e*oes 7 he>d f e direction & rev]b]ations cont9u$ = a numb] ( seconds be=e all 0 /ill aga94 ,speak]s f\nd _! utt]ances ?r[n back at !m1 & auditors all ov] ! h\se exp]i5c$ difficulty 9 und]/&+ :at 0 said4 ,on "o occasion ! ,univ]sity b& play$ a piece :i* featur$ a xylophone solo ) accompanim5t by ! o!r in/rum5ts4 ,x s happ5$ t ! lead] he>d ! e*o m /rongly ?an ! direct s\nd & beat "t ) x4 ,play]s ne> ! xylophone kept "t to ! direct s\nd1 :ile ^? f>!r away foll[$ ! e*o4 ,! confusion may well be imag9$4 ,?us x seem$ t ! ,auditorium 0 doom$ to be an ac\/ical horror2 t speak]s & s+]s w\ld avoid x1 & t auditors w\ld att5d ent]ta9m5ts 9 x only "u prote/4 ,b ! app>5t mis=tune 0 9 "o way a b5efit s9ce x provid$ an opportunity to /udy defective ac\/ics "u exceptionally good conditions & l$ to conclusions t n only all[$ ! ,auditorium to be improv$ b also indicate "s ( ! pitfalls to be avoid$ 9 future con/ruction ( o!r halls4 ,illu/ration3 ,,fig4 #b4 ,,photograph ,,( ,,int]ior4 ,,view ,,( ,,/age4 ,illu/ration3 ,,fig4 #c4 ,,photograph ,,( ,,int]ior4 ,,view ,,t[>d ,,balcony4 ,an inve/igation ( ! ac\/ical prop]ties ( ! ,auditorium 0 begun 9 #aijh & has cont9u$ = six ye>s4 ,x 0 decid$ at ! outset n to use 8cut & try0 me?ods ( cure1 b to attack ! problem sy/ematically s t g5]al pr9ciples c\ld be f\nd1 if possible1 t w\ld apply n only to ! case be+ inve/igat$ b to auditoriums 9 g5]al4 ,?is plan ( proc$ure delay$ ! solution ( ! problem1 s9ce x became necess>y to /udy ! !ory ( s\nd & c>ry out laboratory inve/igations at ! same "t t ! complex conditions 9 ! ,auditorium 7 be+ consid]$4 ,! au?or sp5t "o ye> ( ! six abroad /udy+ ! !ory ( ac\/ics & inspect+ v>i\s auditoriums4 ,! ma9 e*oes 9 ! ,auditorium 7 locat$ by means ( a new me?od = trac+ ! pa? ( s\nd1 ! "t ( rev]b]ation 0 det]m9$ by ,sab9e's me?od1 & a g5]al diagnosis ( ! ac\/ical defects 0 made4 ,hang+s & curta9s 7 in/all$ 9 accordance ) ! results ( ! /udy s t f9ally ! ac\/ical prop]ties 7 improv$4 ,ackn[l$gm5t4--,! au?or desires to express 8 great appreciation ( ! advice & enc\ragem5t giv5 by ,presid5t ,e4 ,j4 ,james1 ,sup]vis+ ,ar*itect ,j4 ,m4 ,:ite1 & ,pr(essor ,a4 ,p4 ,c>man ( ! ,physics ,dep>tm5t4 ,he desires also to ackn[l$ge ! mat]ial assi/ance *e]fully r5d]$ by ! workm5 at ! ,univ]sity1 :i* contribut$ 9 no small degree to ! successful solution ( ! problem4 ,,ii4 ,,behavior ,,( ,,s\nd ,,waves ,,9 ,a ,,room4 ,:5 a speak] addresses an audi5ce1 ! s\nds he utt]s proce$ 9 ev] wid5+ sph]ical waves until !y /rike ! b\nd>ies ( ! room4 ,"h ! s\nd is p>tly reflect$1 p>tly transmitt$1 & ! re/ absorb$4 ,! am\nts ( reflection1 absorption & transmission dep5d on ! "* ( ! walls4 ,a h>d1 smoo? wall reflects mo/ ( ! s\nd s t b little is transmitt$ or absorb$4 ,9 ! case ( a por\s wall or a yield+ wall1 ! absorption & transmission are great]1 & ! reflection is less4 ,aft] /rik+ a numb] ( reflect+ surfaces1 ! en]gy is us$ up & ! s\nd dies out4 ,! reflection ( s\nd produces c]ta9 advantages & disadvantages = ! ac\/ics4 ,:5 x is consid]$ t s\nd travels ab\t #aajj feet a second x may be se5 t a room ( ord9>y size is almo/ imm$iately fill$ ) s\nd because ( ! _m reflections4 ,9 a room #dj feet squ>e1 = in/ance1 ! numb] ( reflections p] second betwe5 opposite walls is #aajj #dj1 or approximately #bg4 ,! numb] is really great] ?an ?is1 s9ce ! s\nd t goes into ! corn]s is reflect$ mu* m frequ5tly ?an out 9 ! middle :]e ! di/ances betwe5 walls are great]4 ,! result is t ! s\nd mixes ?or\ghly 9 all p>ts ( ! room s z to give ! same av]age int5sity2 t is1 ! s\nd is ( ! same av]age l\dness = all auditors1 ev5 = ^? 9 ! remote/ corn]s4 ,?\gh ! reflection ( s\nd has ! advantage ( fulfill+ ! conditions = l\dness1 x introduces at ! same "t possibilities = sett+ up defective ac\/ics4 ,= in/ance1 :5 ! walls ( ! room are h>d & smoo? v little en]gy is lo/ at ea* impact ( ! s\nd & _m reflections take place be=e x f9ally dies out4 ,?is sl[ decad5ce ( ! s\nd1 or rev]b]ation z x is call$1 is ! mo/ common defect 9 auditoriums4 ,if a speak] talks 9 su* a hall ! auditors h difficulty 9 und]/&+4 ,ea* s\nd1 in/ead ( dy+ out quickly1 p]si/s = "s "t s t ! succe$+ words bl5d ) _! pr$ecessors & set up a mixture ( s\nds :i* produces confusion4 ,! cure = ! tr\ble is br\ght ab\t by ! introduction ( mat]ials su* z c>pets1 tape/ries1 & ! l1 :i* act z absorb]s ( s\nd & r$uce ! "t ( rev]b]ation4 ,:5 music is play$ 9 an auditorium ) a prolong$ rev]b]ation1 ! tones foll[+ "o ano!r bl5d & produce ! same effect z t ( a piano :5 play$ ) ! l\d p$al 9 use4 ,a rev]b]ation is m advantage\s = music ?an = spee*1 s9ce ! prolongation & bl5d+ ( ! musical tones is desir$1 b ! mix+ ( ! words 9 a spee* is a di/9ct disadvantage4 ,:5 cur+ ?is defect = halls us$ = bo? music & speak+1 a middle c\rse mu/ be /e]$1 s t ! rev]b]ation is made some:at long = speak+ & some:at %ort = music1 yet fairly satisfactory = bo?4 ,go+ back to ! consid]ation ( ! reflection ( s\nd1 x is f\nd t ano!r defect may be produc$1 namely1 an e*o4 ,?is is ! case :5 a wall at "s di/ance reflects ! s\nd to ! position ( ! auditor4 ,he he>s ! s\nd fir/ f ! speak]1 !n lat] by reflection f ! wall4 ,! "t int]val betwe5 ! direct & reflect$ s\nd mu/ be great en\gh to all[ two di/9ct impressions to be made4 ,?is "t is ab\t #a_/ae ( a second1 b v>ies ) ! acut5ess ( ! obs]v]4 ,! f>!r (f ! wall is1 ! great] is ! "t int]val & ! m pron\nc$ is ! e*o4 ,if ! wall is n v di/ant1 ! "t int]val is too %ort to all[ two di/9ct impressions to be made1 & ! effect on ! auditor is !n mu* ! same z if 8 neighbor at 8 side speaks ! words ( ! disc\rse 9 8 e> at ! same "t t he gets !m directly f ! speak]4 ,9 case ! reflect+ wall is curv$ s z to focus ! s\nd ! e*oes are mu* m pron\nc$4 ,a curv$ wall :]ev] x may be plac$ 9 an auditorium is ?us always a m5ace to good ac\/ics4 ,!re are o!r actions ( ! s\nd t may result 9 ac\/ical defects4 ,! ph5om5a ( resonance1 = in/ance1 may cause tr\ble4 ,suppose t ! waves ( s\nd imp+e on an ela/ic wall1 n too rigid4 ,if ^! waves are tim$ "r !y set ! wall 9 vibration 9 ! same way t ! bell r+] causes a bell to r+ by a succession ( prop]ly tim$ pulls on ! bell rope4 ,! wall ( ! room w !n vibrate "u ! action ( ?is s\nd ) :i* x is 9 tune & w re9=ce x4 ,n[ suppose a b& is play+ 9 a room4 ,c]ta9 tones are re9=c$1 :ile ! o!rs are n affect$4 ,! orig9al s\nd is !n di/ort$4 ,! action is ! same on ! voice ( ! speak]4 ,! s\nds he utt]s are complex & z !y rea* ! walls c]ta9 compon5ts are re9=c$ & ! quality ( ! s\nd is *ang$4 ,?is action ( resonance may also be caus$ by ! air 9 a room4 ,ea* room has a def9ite pit* to :i* x responds1 ! small] ! volume ( ! room ! high] be+ ! pit*4 ,a l>ge auditorium w\ld respond to ! v l[ pit* ( ! bass drum4 ,9 small rooms & alcoves ! response is made to high] pit*$ tones1 z may be obs]v$ by s++ ! diff]5t notes ( ! scale until a resonance is obta9$4 ,ano!r action ( s\nd causes ! int]f]5ce ( waves4 ,?us ! reflect$ waves may meet ! oncom+ ones & set up conc5trations ( s\nd 9 c]ta9 positions & a de>? ( s\nd 9 o!rs4 ,summ+ up1 x is se5 t ! effects ( s\nd :i* may exi/ 9 a room are l\dness1 rev]b]ation1 e*oes1 resonance1 & int]f]5ce1 & t ! mo/ common defects are rev]b]ation & e*oes4 ,we n[ turn to ! discussion ( ! me?ods ( cure4 ,,iii4 ,,me?ods ,,( ,,improv+ ,,faulty ,,ac\/ics4 ,a4 ,,rev]b]ation ,,& ,,its ,,cure4 ,ev]yone has d\btless obs]v$ t ! holl[ rev]b]ations 9 an empty h\se disappe> :5 ! h\se is furni%$4 ,s1 9 an auditorium1 ! rev]b]ation is less5$ :5 curta9s1 tape/ries1 & ! l are in/all$ 9 suffici5t numb]s4 ,! reason = ?is action is f\nd :5 we inquire :at ultimately becomes ( ! s\nd4 ,s\nd is a =m ( en]gy & en]gy c n be de/roy$4 ,:5 x f9ally dies out1 ! s\nd mu/ be *ang$ to "s o!r =m ( en]gy4 ,9 ! case ( ! walls ( a room1 = in/ance1 x has be5 %[n 9 a prec$+ p>agraph t ! s\nd may be *ang$ into me*anical en]gy 9 sett+ ^! walls 9 vibration4 ,aga91 "s ( ! s\nd may pass out ?r\gh op5 w9d[s & ?us disappe>4 ,! re/ ( ! s\nd1 accord+ to ,"l ,rayleigh1 is trans=m$ by friction into heat4 ,?us#a a high pit*$ s\nd1 su* z a hiss1 be=e x travels any great di/ance is kill$ out by ! friction ( ! air4 ,l[] pit*$ s\nds1 on rea*+ a wall1 set up a friction 9 ! process ( reflection betwe5 ! air p>ticles & ! wall s t "s ( ! en]gy is conv]t$ into heat4#b ,! am\nt ( s\nd en]gy ?us lo/ is small if ! walls are h>d & smoo?4 ,! case is mu* diff]5t1 h[ev]1 if ! walls are r\gh & por\s1 s9ce x appe>s t ! friction 9 ! pores dissipates ! s\nd en]gy into heat4 ,9 ?is connection1 ,lamb#c writes3 8,9 a suffici5tly n>r[ tube ! waves are rapidly /ifl$1 ! me*anical en]gy lo/ be+ ( c\rse conv]t$ into heat4 99 99 99 99 ,:5 a s\nd wave imp+es on a slab :i* is p]meat$ by a l>ge numb] ( v m9ute *annels1 "p ( ! en]gy is lo/1 s f> z ! s\nd is conc]n$1 by dissipation )9 ^! *annels 9 ! way j expla9$4 ,! int]/ices 9 hang+s & c>pets act 9 a simil> mann]1 & x is to ?is cause t ! effect ( su* appliances 9 dead5+ e*oes 9 a room is to be ascrib$1 a c]ta9 proportion ( ! en]gy be+ lo/ at ea* reflection4 ,x is to be obs]v$ t x is only ?r\gh ! action ( true dissipative =ces1 su* z viscosity & !rmal conduction1 t s\nd c die out 9 an enclos$ space1 no m]e modifications ( ! waves by irregul>ities be+ ( any avail40 ,x %\ld be po9t$ out 9 ?is connection t any me*anical break+ up ( ! s\nd by relief "w on ! walls or by ob/acles 9 ! room w n prim>ily dim9i% ! en]gy ( ! s\nd4 ,^! may break up ! regul> reflection & elim9ate e*oes1 b ! s\nd en]gy z su* disappe>s only :5 friction is set up4 ,! foll[+ quotation f ,rayleigh#d emphasizes ^! conclusions3 8,9 l>ge spaces1 b\nd$ by non-por\s walls1 ro(1 & floor1 & ) few w9d[s1 a prolong$ resonance seems inevitable4 ,! mitigat+ influ5ce ( ?ick c>pets 9 su* cases is well kn[n4 ,! application ( simil> mat]ial to ! walls & ro( appe>s to (f] ! be/ *ance ( fur!r improvem5t40 ,exp]im5tal ,"w on ,cure ( ,rev]b]ation4--,! mo/ important exp]im5tal "w 9 apply+ ?is pr9ciple ( ! absorb+ p[] ( c>pets1 curta9s1 etc41 has be5 done by ,pr(essor ,wallace ,c4 ,sab9e ( ,h>v>d ,univ]sity4#e ,9 a set ( int]e/+ exp]im5ts la/+ ov] a p]iod ( f\r ye>s1 he 0 able to d$uce a g5]al relation betwe5 t1 ! "t ( rev]b]ation1 ,v1 ! volume ( ! room1 & a1 ! absorb+ p[] ( ! diff]5t mat]ials pres5t4 ,?us3 t #j4afd ,v a 7#a7 ,= good ac\/ical conditions1 t is1 = a %ort "t ( rev]b]ation1 ! volume ,v %\ld be small & ! absorb+ mat]ials1 repres5t$ by a1 l>ge4 ,?is is ! case 9 a small room ) pl5ty ( curta9s & rugs & furniture4 ,if1 h[ev]1 ! volume ( ! room is great1 z 9 ! case ( an auditorium1 & ! am\nt ( absorb+ mat]ials small1 a tr\blesome rev]b]ation w result4 ,pr(essor ,sab9e det]m9$ ! absorb+ p[]s ( a numb] ( diff]5t mat]ials4 ,call+ an op5 w9d[ a p]fect absorb] ( s\nd1 ! results obta9$ may be writt5 approximately z foll[s3 ,"o squ>e met] ( op5 w9d[ space #a4jjj ,"o squ>e met] ( glass1 pla/]1 or brick 4#jbe ,"o squ>e met] ( heavy rugs1 curta9s1 etc4 4#be ,"o squ>e met] ( hair felt1 #a in* ?ick 4#ge ,"o squ>e met] ( audi5ce 4#if ,^! values1 toge!r ) ! =mula1 all[ a calculation to be made 9 advance ( con/ruction = ! "t ( rev]b]ation4 ,?is pione] "w cle>$ ! subject ( ar*itectural ac\/ics f ! fog ( my/]y t hung ov] x & all[$ ! ess5tial pr9ciples to be se5 9 ! light ( sci5tific exp]im5t4 ,9 a lat] inve/igation#f ,sab9e %[$ t ! rev]b]ation dep5d$ also on ! pit* ( s\nd4 ,z a concrete example1 ! high notes ( a viol9 might be less rev]b]ant ) a l>ge audi5ce ?an ! l[] tones ( ! bass viol1 al?\gh bo? might h ! same rev]b]ation 9 ! room ) no audi5ce4 ,aga91 ! voice ( a man ) notes ( l[ pit* might give satisfactory results 9 an auditorium :ile ! voice ( a woman ) high] pit*$ notes w\ld be unsatisfactory4 ,^! consid]ations %[ t ! ac\/ics 9 an auditorium v>y ) o!r factors ?an ! volume ( ! room & ! am\nt ( absorb+ mat]ial pres5t4 ,! audi5ce may be l>ge or small1 ! speak]'s voice high or l[1 ! ent]ta9m5t a musical numb] or an address4 ,! be/ arrangem5t = good ac\/ics is !n a compromise :]e ! av]age conditions are satisfi$4 ,! solution (f]$ by ,pr(essor ,sab9e is su* an av]age "o1 & has prov$ satisfactory 9 practice4 ,! problem ( ar*itectural ac\/ics has be5 attack$ exp]im5tally by o!r work]s4 ,/ew>t#g propos$ a cure = ! poor ac\/ical conditions 9 ! ,sibley ,auditorium at ,cornell ,univ]sity4 ,8 exp]im5ts confirm$ ! "w ( ,sab9e4 ,m>age#h1 aft] inve/igat+ ! prop]ties ( six halls 9 ,p>is1 approv$ ,sab9e's results & advocat$ a "t ( rev]b]ation ( f to #a second = ! case ( spee*4 ,=mulae = ,rev]b]ation ( ,s\nd 9 a ,room4--,on ! !oretical side1 ,sab9e's =mula has be5 develop$ by ,frankl91#i :o obta9$ ! relation t #j4afbe ,v a1 an int]e/+ confirmation1 s9ce ,sab9e's exp]im5tal value = ! con/ant 0 #j4afd4 ,a lat] developm5t has be5 giv5 by ,jg]1#aj :o assumes = a room ^: dim5sions are n great] ?an ab\t #fj feet1 t ! s\nd1 aft] fill+ ! room1 passes equally 9 all directions ?r\gh any po9t1 & t ! av]age en]gy is ! same 9 diff]5t p>ts ( ! room4 ,by us+ ! !ory ( probability & consid]+ t a beam ( s\nd 9 any direction may be lik5$ to a p>ticle ) a def9ite velocity1 he 0 able to d$uce ,sab9e's =mula & write d[n ! factors t ent] into ! con/ants4 ,apply+ 8 results to ! case ( reflection ( s\nd f a wall1 he %[$ t s\nd w\ld be reflect$ 9 great] volume :5 ! mass ( ! wall 0 increas$ & ! pit* ( ! s\nd made high]4 ,he %[$ also t :5 s\nd imp+es on a por\s wall1 m en]gy is absorb$ :5 ! pit* ( ! s\nd is high ?an :5 x is l[1 s9ce ! vibrations ( ! air are m frequ5t1 & m friction is introduc$ 9 ! int]/ices ( ! mat]ial4 ,b4 ,,e*oes ,,& ,,_! ,,rem$y4 ,an e*o is set up by a reflect+ wall4 ,if an obs]v] /&s "s di/ance f ! front ( a cliff & claps 8 h&s1 or %\ts1 he f9ds t ! s\nd is return$ to him f ! cliff z an e*o4 ,s1 9 an auditorium1 an auditor ne> ! speak] gets ! s\nd fir/ directly f ! speak]1 !n1 an in/ant lat]1 a /rong repetition ( ! s\nd by reflection f a di/ant wall4 ,?is e*o is m pron\nc$ if ! wall is curv$ & ! auditor is at ! po9t :]e ! s\nd is focus$4 ,to cure su* an e*o1 two me?ods may be consid]$4 ,"o me?od consi/s 9 *ang+ ! =m ( ! wall s t ! reflect$ s\nd no long] sets up ! e*o4 ,t is1 ei!r *ange ! angle ( ! wall1 s t ! reflect$ s\nd is s5t 9 a new direction :]e x may be absorb$ or :]e x may re9=ce ! direct s\nd )\t produc+ any e*oes1 or else modify ! surface ( ! wall by relief "w or by panels ( absorb+ mat]ial1 s t ! /rong reflect$ wave is brok5 up & ! s\nd is scatt]$4 ,! second me?od is to make ! reflect+ wall a 8p]fect0 absorb]1 s t ! incid5t s\nd is swall[$ up & little or none reflect$4 ,^! me?ods h be5 designat$ z 8surgical0 & 8m$ic9al0 respectively4 ,ea* me?od has its disadvantages4 ,*ang+ ! =m ( ! walls 9 an auditorium is likely to d viol5ce to ! ar*itectural design4 ,on ! o!r h&1 !re are no p]fect absorb]s1 except op5 w9d[s1 & ^! c seldom be appli$4 ,! cure 9 ea* case is1 !n1 a matt] ( /udy ( ! special conditions ( ! auditorium4 ,usually a comb9ation ( ! surgical & ! m$ic9al cures is adopt$4 ,= in/ance1 c(f]+ a wall s t panels ( absorb+ mat]ial may be introduc$ has be5 f\nd to "w well 9 bett]+ ! ac\/ics1 & also1 9 _m cases1 x fits 9 ) ! ar*itectural features4 ,c4 ,,popul> ,,conception ,,( ,,cures4--,,use ,,( ,,wires ,,& ,,s\nd+ ,,bo>ds4 ,a few words %\ld be writt5 conc]n+ ! popul> notion t wires & s\nd+ bo>ds are effective 9 cur+ faulty ac\/ics4 ,exp]im5ts & obs]vations %[ t wires are ( practically no b5efit1 & s\nd+ bo>ds c be us$ only 9 special cases4 ,wires /ret*$ 9 a room sc>cely affect ! s\nd1 s9ce !y pres5t too small a surface to di/urb ! waves4 ,!y h mu* ! same effect on s\nd waves t a fi% l9e 9 ! wat] has on wat] waves4 ,! idea has1 p]haps1 gr[n into prom95ce because ( ! action ( a piano 9 respond+ to ! notes ( a s+]4 ,! piano has e advantage ov] a wire 9 an auditorium4 ,x has a l>ge numb] ( /r+s tun$ to diff]5t pit*es s t x responds to any note sung4 ,x also has a s\nd+ bo>d t re9=ces /rongly ! s\nd ( ! /r+s4 ,f9ally1 ! s+] is usually ne> ! piano4 ,! wire 9 ! auditorium responds to only "o tone ( ! _m likely to be pres5t1 x has no s\nd+ bo>d1 & ! s+] is "s di/ance away4 ,b little effect1 !re=e1 is to be expect$4 ,! au?or has visit$ a numb] ( halls :]e wires h be5 in/all$1 & has yet to f9d a case :]e pron\nc$ improvem5t has result$4#aa ,sab9e#ab cites a case :]e five miles ( wire 7 /ret*$ 9 a hall )\t help+ ! ac\/ical conditions4 ,x is curi\s t s errone\s a conception has gr[n up 9 ! public m9d ) s little exp]im5tal basis to support x4 ,s\nd+ ,bo>ds4--,s\nd+ bo>ds or1 m prop]ly1 reflect+ bo>ds1 h value 9 special cases4 ,"s exp]im5ts are describ$ lat] :]e pron\nc$ effects 7 obta9$4 ,! s\nd+ bo>d %\ld be ( special design to fit ! conditions "u :i* x is to be us$4 ,model+ ,new ,auditoriums aft] ,old ,ones ) ,good ,ac\/ics4--,ano!r sugge/ion (t5 made is = ar*itects to model auditoriums aft] ^? already built t h good ac\/ical prop]ties4 ,x does n foll[ t halls s model$ w be successful1 s9ce ! mat]ials us$ 9 con/ruction are n ! same ye> aft] ye>4 ,= in/ance1 a few ye>s ago x 0 ! usual cu/om to put lime pla/] on wood5 la?2 n[ x is frequ5tly ! practice to put gypsum pla/] on metal la?1 :i* =ms an entirely diff]5t k9d ( a surface4 ,?is latt] arrangem5t makes h>d1 non-por\s walls :i* absorb b little s\nd1 & ?us aggravate ! rev]b]ation4 ,fur!r1 a new hall usually is *ang$ some:at 9 =m f ! old "o1 to suit ! ideas ( ! ar*itect1 & x is v likely t ! *anges w affect ! ac\/ics4 ,d4 ,,! ,,effect ,,( ,,! ,,v5tilation ,,sy/em ,,on ,,! ,,ac\/ics4 ,at fir/ ?\ght x might seem t ! v5tilation sy/em 9 a room w\ld affect ! ac\/ical prop]ties4 ,! air is ! m$ium t transmits ! s\nd4 ,x has be5 %[n t ! w9d has an action 9 *ang+ ! direction ( propagation ( s\nd4#ac ,s\nd is also reflect$ & refract$ at ! b\nd>y ( gases t diff] 9 d5sity & temp]ature4#ad ,x is f\nd1 h[ev]1 t ! effect ( ! usual v5tilation curr5ts on ! ac\/ics 9 an auditorium is small4 ,! temp]ature diff]5ce betwe5 ! heat$ curr5t & ! air 9 ! room is n great en\gh to affect ! s\nd appreciably1 & ! motion ( ! curr5t is too sl[ & ov] too %ort a di/ance to *ange ! action ( ! s\nd to any m>k$ ext5t4#ae ,"u special circum/ances1 ! heat+ & v5tilat+ sy/ems may prove disadvantage\s4#af ,a hot /ove or a curr5t ( hot air 9 ! c5t] ( ! room w s]i\sly di/urb ! action ( s\nd4 ,any irregul>ity 9 ! air curr5ts s t %eets ( cold & heat$ air fluctuate ab\t ! room w also modify ! regul> action ( ! s\nd & produce confusion4 ,! object to be /riv5 = is to keep ! air 9 ! room z homog5e\s & /eady z possible4 ,hot /oves1 radiators1 & curr5ts ( heat$ air %\ld be kept ne> ! walls & out ( ! c5t] ( ! room4 ,x is ( "s small advantage to h ! v5tilation curr5t g 9 ! same direction t ! s\nd is to g1 s9ce a w9d t5ds to c>ry ! s\nd ) x4 ,,iv4 ,,! ,,inve/igation ,,9 ,,! ,,auditorium ,,at ,,! ,,univ]sity ,,( ,,ill9ois4 ,a4 ,,prelim9>y ,,"w4 ,z already /at$1 a *aos ( s\nd 0 set up :5 an obs]v] 9 ! ,auditorium spoke or %\t$ or clapp$ 8 h&s4 ,bo? e*oes & rev]b]ations 7 pres5t & c\ld be he>d 9 all p>ts ( ! room1 ?\gh ! e*oes seem$ to be /ronge/ on ! /age & 9 ! balcony4 ,! prospects = bett]+ ! ac\/ics 7 n v enc\rag+4 ,luckily1 ! cure = ! rev]b]ation 0 fairly simple1 s9ce ,sab9e's me?od gave a def9ite proc$ure t c\ld be appli$ to ?is case4 ,! cure = ! e*o1 h[ev]1 0 yet to be f\nd4 ,x 0 fir/ necess>y to f9d out :i* walls set up ! defect4 ,! attempt to locate e*oes by g5]at+ a s\nd & li/5+ ) ! e> met ) only p>tial success4 ,! e> is s5sitive en\gh b becomes confus$ :5 _m e*oes are pres5t1 com+ app>5tly f e direction1 s t ! evid5ce ?us obta9$ is n altoge!r conclusive4 ,x became app>5t t ! successful solution lay 9 fix+ ! att5tion on ! s\nd go+ 9 a p>ticul> direction & f9d+ out :]e x w5t aft] reflection2 !n trac+ out ! pa? 9 ano!r p>ticul> direction1 & s on until ! evid5ce obta9$ gave "s h9t ( ! g5]al action ( ! s\nd4 ,illu/ration3 ,,fig4 #d4 ,,wat* ,,z ,,s\rce ,,( ,,s\nd1 ,,back$ ,,by ,a ,,concave ,,reflector4 ,! fir/ /ep 9 ! application ( ?is pr9ciple 0 to use a fa9t s\nd :i* c\ld n be he>d at any great di/ance unless re9=c$ 9 "s way4 ,! ticks ( a wat* 7 direct$1 by means ( a reflector 7,fig4 #d7 to c]ta9 walls suspect$ ( giv+ e*oes4 ,us+ ! relation t ! angle ( incid5ce equals ! angle ( reflection1 ! reflect$ s\nd 0 readily locat$1 & ! wat* ticks he>d di/9ctly aft] !y _h travel$ a total di/ance z great z #gj to #hj feet f ! s\rce4 ,9 a lat] exp]im5t1 a metronome 0 us$ :i* gave a l\d] s\nd4 ,x 0 enclos$ 9 a s\nd-pro( /ructure 7,fig4 #e7 ) only "o op5+1 s t ! s\nd c\ld be direct$ by means ( a horn4 ,?is me?od 0 sugge/$ by ! "w ( ,gu/av ,lyon 9 ! ,hall ( ! ,trocad]o at ,p>is1#ag :]e a some:at simil> arrangem5t 0 us$4 ,! me?od 0 successful & v]ifi$ ! obs]vations tak5 previ\sly4 ,illu/ration3 ,,fig4 #e4 ,,metronome ,,z ,,s\rce ,,( ,,s\nd4 ,illu/ration3 ,,fig4 #f4 ,,arc-,,light ,,z ,,s\rce ,,( ,,s\nd4 ,?\gh ! results obta9$ ) ! wat* & metronome seem$ conclusive1 yet ! obs]v] 0 n always confid5t ( ! results4 ,a fur!r me?od 0 s\ght1 & a m satisfactory "o f\nd by us+ an alt]nat+ curr5t arc-light at ! focus ( a p>abolic reflector 7,fig4 #f74 ,9 addition to ! light1 ! arc gave =? a hiss+ s\nd1 :i* 0 ( %ort wave l5g? & !re=e exp]i5c$ b little diffraction4 ,! bundle ( light rays 01 !re=e1 accompani$ by a bundle ( s\nd1 bo? com+ f ! same s\rce & subject to ! same law ( reflection4 ,! pa? ( ! s\nd 0 easily f\nd by not+ ! position ( ! spot ( light on ! wall4 ,! reflect$ s\nd 0 locat$ by apply+ ! relation t ! angles ( incid5ce & reflection are equal4 ,! arc-light s\nd 0 int5se & gave ! obs]v] confid5ce 9 results t 0 lack+ 9 ! o!r me?ods4 ,to trace successive reflections1 small mirrors 7 fa/5$ to ! reflect+ walls s t ! pa? ( ! reflect$ s\nd 0 indicat$ by ! reflect$ light4 ,a 8diagnosis0 ( ! ac\/ical tr\bles ( ! ,auditorium 0 !n made by ?is me?od4 ,x %\ld be not$ "h t ! arc-light s\nd is n ! same z ! s\nds ( music or spee*1 ^! latt] ones be+ ( l[] pit* & ( long] wave l5g?4 ,x 01 !re=e1 a matt] ( d\bt :e!r ! results obta9$ w\ld hold also = ! case ( spee* or music4 ,te/s made by obs]v]s /ation$ 9 ! ,auditorium :5 musical numb]s & spee*es 7 r5d]$1 h[ev]1 v]ifi$ ! g5]al conclusions obta9$ ) ! arc-light4 ,x %\ld be po9t$ out 9 ?is connection t !re is an objection to apply+ ! 8ray0 me?od ( geometrical optics to ! case ( s\nd4 ,x is mu* m difficult to get a ray ( s\nd ?an x is to get a ray ( light4#ah ,?is is due to ! diff]5ce 9 ! wave l5g?s 9 ! two cases4 ,x appe>s t ! waves are diffract$1 or spread out1 9 proportion to _! l5g?1 ! long] waves be+ spread out to a great] ext5t4 ,! %ort waves ( light f ! sun1 = in/ance1 z !y come ?r\gh a w9d[ m>k out a %>p patt]n on ! floor1 :i* %[s t ! waves proce$ 9 /raight l9es ) b little diffraction or spread+4 ,f> diff]5t is x ) ! long] waves ( s\nd4 ,if ! w9d[ is op51 we are able to he> practically all ! s\nds f outdoors1 ev5 t ( a wagon ar\nd ! corn]1 al?\gh we may be at ! o!r end ( ! room away f ! w9d[4 ,! long] s\nd waves spread out & b5d at "r angles ar\nd corn]s1 s t x is almo/ impossible to get a s\nd %ad[ ) !m4 ,fur!rmore1 9 ! matt] ( reflection1 x appe>s t ! area ( ! reflect+ wall mu/ be comp>able ) ! l5g? ( ! waves be+ reflect$4 ,9 ! case ( light1 ! waves are v m9ute1 h5ce a mirror c be v small & yet be able to set up a reflection2 b s\nd waves are ( great] l5g?1 ! av]age wave l5g? ( spee* 7#de cm47 be+ ab\t #gjj #jjj times long] ?an ! wave l5g? ( yell[ light 74#jjjjf cm471 h5ce ! reflect+ surface mu/ be correspond+ly l>g]4 ,an illu/ration w p]haps make ?is cle>]4 ,suppose a po/ "o foot squ>e projects ?r\gh a wat] surface4 ,! small ripples on ! wat] w be reflect$ easily f ! po/1 b ! l>ge wat] waves pass by almo/ z if ! po/ 7 n !re4 ,! reflect+ surface mu/ h an area comp>able ) ! size ( ! wave if x is to cause an effective reflection4 ,relief "w 9 auditoriums1 if ( small dim5sions1 w affect only ! high pit*$ s\nds1 i4 e41 ^? ( %ort wave l5g?1 :ile ! l[ pit*$ s\nds ( long wave l5g? are reflect$ mu* ! same z f a r r\gh wall4 ,x is also %[n t ! area ( ! reflect+ surface is dep5d5t on its di/ance f ! s\rce ( s\nd & f ! obs]v]2 ! great] ^! di/ances are ! l>g] mu/ be ! reflect+ surface4#ai ,^! consid]ations all %[ t ! reflection ( s\nd is a complicat$ matt]4 ,! dim5sions ( a wall to reflect s\nd1 or ( relief "w to scatt] x1 are det]m9$ by ! wave l5g? & by ! v>i\s o!r factors m5tion$4 ,x %\ld be said ) caution t a 8ray0 ( s\nd is reflect$ 9 a def9ite way f a small bit ( relief "w4 ,we mu/ deal ) bundles ( s\nd1 n too %>ply b\nd$1 & h !m /rike surfaces ( consid]able area 9 ord] to produce reflections ) any complet5ess4 ,illu/ration3 ,,fig4 #g4 ,,longitud9al ,,section ,,%[+ ,,! ,,*ief ,,conc5trations ,,( ,,s\nd1 ,,! ,,diffraction ,,effects ,,be+ ,,disreg>d$4 ,b4 ,,details ,,( ,,! ,,ac\/ical ,,survey ,,9 ,,! ,,auditorium4 ,! g5]al effect ( ! walls ( ! ,auditorium on ! s\nd may be anticipat$ by consid]+ analog\s cases 9 geometrical optics1 b ) ! re/rictions on 8rays0 describ$ 9 ! prec$+ p>agraph4 ,! s\nd does n actually conf9e itself to ! %>p b\nd>ies %[n4 ,! diagrams are int5d$ to indicate ! ma9 effect ( ! s\nd 9 ! region s b\nd$4 ,fig4 #g gives su* an idea = ! conc5tration ( s\nd 9 ! longitud9al section ( ! ,auditorium4 ,! plan foll[$ 9 ! exp]im5tal "w 0 to anticipate ! pa? ( ! s\nd z indicat$ 9 ,fig4 #g1 !n to v]ify ! results ) ! arc-light reflector4 ,figs4 #h & #i %[ ! effect ( ! re> wall 9 ! balcony 9 =m+ e*oes on ! /age4 ,! speak] 0 p>ticul>ly un=tunate1 be+ afflict$ ) no less ?an t5 e*oes4 ,illu/ration3 ,,fig4 #h4 ,,longitud9al ,,section ,,%[+ ,,h[ ,,s\nd ,,is ,,return$ ,,to ,,! ,,/age ,,to ,,=m ,,an ,,e*o4 ,illu/ration3 ,,fig4 #i4 ,,longitud9al ,,section ,,%[+ ,,=mation ,,( ,,e*o ,,on ,,! ,,/age4 ,! h>d1 smoo?1 circul> wall b\nd+ ! ma9 floor "u ! balcony gave e*oes z %[n 9 ,fig4 #aj1 ! s\nd go+ also 9 ! rev]se direction ( ! arr[s4 ,illu/ration3 ,,fig4 #aj4 ,,plan ,,( ,,auditorium ,,%[+ ,,action ,,( ,,re> ,,wall ,,on ,,! ,,s\nd4 ,illu/ration3 ,,fig4 #aa4 ,,plan ,,( ,,auditorium ,,%[+ ,,conc5tration ,,( ,,s\nd ,,by ,,! ,,re> ,,wall4 ,illu/ration3 ,,fig4 #ab4 ,,?is ,,figure ,,tak5 ,,) ,,fig4 #i ,,%[s ,,h[ ,,an ,,e*o ,,is ,,set ,,up ,,on ,,! ,,/age4 ,a m compreh5sive idea ( ! action ( ?is wall is %[n 9 ,fig4 #aa4 ,?is reflect$ s\nd 0 small 9 am\nt & !re=e n a s]i\s disadvantage4 ,! cases cit$ 7 fairly easy to det]m9e s9ce ! bundles ( s\nd consid]$ 7 conf9$ closely to ei!r a v]tical or a horizontal plane = :i* ! plans ( ! build+ gave "s idea ( ! probable pa? ( ! s\nd4 ,= o!r planes1 ! pa?s foll[$ c\ld be anticipat$ by analogy f ! results already f\nd4 ,fig4 #ab %[s 9 p]spective ! developm5t ( ! result express$ 9 ,fig4 #i4 ,a squ>e bundle ( s\nd />ts f ! /age & /rikes ! sph]ical surface ( ! dome4 ,aft] reflection1 x is br\ght to a po9t focus1 z %[n1 & spreads out until x /rikes ! v]tical cyl9drical wall 9 ! re> ( ! balcony4 ,?is wall reflects x to a l9e focus1 aft] :i* x proce$s to ! /age4 ,auditors on all p>ts ( ! /age compla9$ ( he>+ e*oes4 ,ref]r+ to ,fig4 #g1 x is se5 t ! ar* ov] ! /age reflects s\nd back to ! /age4 ,fig4 #ac %[s 9 p]spective ! focus+ action ( ?is ov]head ar*4 ,fig4 #ad %[s ! effect ( ! second ar*4 ,"s ( ?is s\nd is reflect$ to ! /age & to ! seats 9 front ( ! /age2 o!r portions1 /rik+ m ne>ly horizontally1 are reflect$ to ! side balconies4 ,! e*oes are n /rong except = high pit*$ notes ) %ort wave l5g?s1 s9ce ! wid? ( ! ar* is small4 ,illu/ration3 ,,fig4 #ac4 ,,p]spective ,,( ,,/age ,,%[+ ,,focus+ ,,action ,,( ,,ar* ,,on ,,s\nd4 ,illu/ration3 ,,fig4 #ad4 ,,p]spective ,,( ,,/age ,,%[+ ,,focus+ ,,action ,,( ,,second ,,ar*4 ,illu/ration3 ,,fig4 #ae4 ,,transv]se ,,section ,,%[+ ,,h[ ,,mo/ ,,pron\nc$ ,,e*oes ,,are ,,set ,,up ,,by ,,! ,,two ,,concave ,,surfaces4 ,pass+ n[ to ! transv]se section1 ,fig4 #ae1 we f9d ! mo/ pron\nc$ e*oes 9 ! ,auditorium4 ,if an obs]v] g5]ates a s\nd 9 ! middle ( ! room directly "u ! c5t] ( ! skylight1 di/9ct e*oes are set up4 ,a bundle ( s\nd passes to ! concave surface :i* conv]ges ! s\nd to a focus1 aft] :i* x spreads out aga9 to ! o!r concave surface & is aga9 conv]g$ to a focus ne>ly at ! />t+ po9t4 ,! di/ance travel$ is ab\t #bbe feet1 tak+ ab\t second1 s t ! conditions are "r = sett+ up a /rong e*o4 ,?is e*o is duplicat$ by ! s\nd :i* goes 9 ! rev]se ( ! pa? j describ$4 ,ano!r e*o1 some:at less /rong1 is =m$ by ! s\nd t goes to ! dome ov]head & :i* is reflect$ almo/ /raight back1 s9ce ! obs]v] is ne>ly at ! c5t] ( ! sph]e ( :i* ! dome is a "p4 ,^! e*oes repeat !mselves1 = ! s\nd does n /op on rea*+ ! />t+ po9t b is reflect$ f ! floor & repeats ! action j describ$4 ,z _m z t5 di/9ct e*oes h be5 g5]at$ by a s+le impulse ( s\nd4 ,illu/ration3 ,,fig4 #af4 ,,action ,,( ,,s\nd ,,9 ,,caus+ ,,e*o ,,on ,,! ,,/age4 ,! e*o %[n 9 ,fig4 #ae is repeat$ 9 a some:at modifi$ =m = a s\nd g5]at$ on ! /age by a speak]4 ,fig4 #af %[s ! pa? tak5 by ! s\nd4 ,?is e*o is duplicat$ by ! s\nd t goes 9 ! rev]se direction ( ! arr[s1 s ! speak] is greet$ f bo? sides4 ,fig4 #ag is a p]spective %[+ ! pa?4 ,! s\nd does n conf9e itself closely to a geometrical patt]n1 z %[n 9 ! picture1 b spreads out by diffraction4 ,! ma9 effect is %[n by ! figure4 ,illu/ration3 ,,fig4 #ag4 ,,p]spective ,,%[+ ,,h[ ,,an ,,e*o ,,is ,,=m$ ,,on ,,! ,,/age ,,by ,,two ,,reflections4 ,,diffraction ,,effects ,,are ,,n ,,consid]$ ,,9 ,,?is ,,draw+4 ,?us f> only ! e*oes t rea*$ ! /age h be5 describ$4 ,o!r e*oes 7 f\nd 9 o!r p>ts ( ! hall1 & x seem$ t few places 7 free f !m4 ,! side walls 9 ! balcony1 = in/ance1 7 in/rum5tal 9 caus+ /rong e*oes 9 ! re> ( ! balcony4 ,fig4 #ah %[s 9 p]spective ! action ( "o ( ^! walls4 ,^! two surfaces 7 simil> 9 %ape & symmetrically plac$4 ,ea* 0 ! upp] portion ( a concave surface ) its c5t] ( curvature 9 ! c5t] ( ! build+ "u ! dome4 ,! g5]al effect ( ! left h& wall 0 to conc5trate ! s\nd fall+ on x 9 ! "r h& seats 9 ! balcony4 ,"s ( ! s\nd /ruck ! opposite wall & 0 reflect$ to ! /age1 z %[n 9 ,fig4 #ag4 ,auditors :o s\ght ! fur!rmo/ re> seats 9 ! balcony to escape e*oes 7 ?us caught by ?is unexpect$ action ( ! s\nd4 ,! "r h& wall act$ 9 a simil> way to s5d ! s\nd to ! upp] left balcony4 ,illu/ration3 ,,fig4 #ah4 ,,p]spective ,,%[+ ,,s\nd ,,reflect$ ,,f ,,concave ,,wall ,,9 ,,balcony4 ,,diffraction ,,n ,,consid]$4 ,! dome surface conc5trates mo/ ( its s\nd ne> ! front ( ! c5tral portion ( ! balcony & ! gr\nd floor 9 front ( ! balcony 9 ! =m ( a cau/ic cone4 ,figs4 #g1 #i & #aa give "s conception ( h[ a conc5tration ( s\nd is caus$ by ?is sph]ical surface4 ,! e*o 9 ! front portion ( ! balcony 0 especially di/9ct4 ,on "o occasion1 9 ?is place1 ! au?or 0 able to he> ! speak] m cle>ly f ! e*o ?an by li/5+ to ! direct s\nd4 ,m9or e*oes 7 set up by ! horizontal ar* surfaces 9 ! balcony4 ,! s\nd f ! /age 0 conc5trat$ by reflection f ^! surfaces & !n pass$ to a second reflection f ! concave surfaces back ( !m4 ,auditors 9 ! side balcony 7 ?us disagreeably />tl$ by hav+ s\nd come f ov]head f ! re>4 ,c4 ,,conclusion ,,drawn ,,f ,,! ,,ac\/ical ,,survey4 ,! results ( ! survey %[ t curv$ walls are l>gely responsible = ! =mation ( e*oes because !y conc5trate ! reflect$ s\nd4 ,x seems desirable1 !re=e1 to emphasize ! dang] ( us+ su* walls unless _! action is annull$ by absorb+ mat]ials or relief "w4 ,l>ge halls ) curv$ walls are almo/ sure to h ac\/ical defects4 ,d4 ,,me?ods ,,employ$ ,,to ,,improve ,,! ,,ac\/ics4 ,reflect+ ,bo>ds4--,! provisional cure 0 br\ght ab\t gradually by try+ diff]5t devices sugge/$ by ! diagnosis4 ,9 "o set ( exp]im5ts s\nd+ bo>ds ( v>i\s %apes & sizes 7 us$4 ,a flat bo>d ab\t five feet squ>e plac$ at an incl9e ov] ! position ( ! speak] produc$ little effect4 ,a l>g] canvas surface1 ab\t #ab by #bj feet1 0 n mu* bett]4 ,a p>abolic reflector1 h[ev]1 gave a pron\nc$ effect4 ,?is reflector 0 m\nt$ ov] a pulpit at "o end ( ! /age & s]v$ to int]cept mu* ( ! s\nd t o!rwise w\ld h gone to ! dome & produc$ e*oes4 ,! pa? ( ! reflect$ s\nd 0 p>allel to ! axis ( ! p>aboloid ( :i* ! reflector 0 a qu>t] section4 ,!re 0 no difficulty 9 trac+ out ! reflect$ s\nd4 ,auditors 9 ! pa? ( ! reflect$ rays report$ an e*o1 b auditors 9 o!r p>ts ( ! ,auditorium 7 rem>kably free f ! usual tr\bles4 ,! device 0 n us$ p]man5tly1 s9ce _m speak]s object$ to ! rais$ plat=m4 ,moreov]1 x 0 n a complete cure1 s9ce x 0 n suit$ = b& conc]ts & o!r ev5ts1 :]e ! entire /age 0 us$4 ,ano!r reflector simil> 9 %ape to ! "o j describ$ is %[n 9 ,figs4 #ba & #bb4 ,illu/ration3 ,,fig4 #ai4 ,,reflect+ ,,bo>d ,,9 ,,process ,,( ,,con/ruction4 ,illu/ration3 ,,fig4 #bj4 ,,f9i%$ ,,reflector4 ,,h>d ,,pla/] ,,on ,,wire ,,la?4 ,sab9e's ,me?od4--,! "t ( rev]b]ation 0 det]m9$ by ,sab9e's me?od4 ,an organ pipe mak+ approximately #ebf vibrations a second 0 bl[n = ab\t ?ree seconds & !n /opp$4 ,an auditor li/5$ to ! decreas+ s\nd1 & :5 x di$ out made a record electrically on a *ronograph drum4 ,! "t ( rev]b]ation 0 f\nd to be #e4ij seconds1 ?is be+ ! mean ( #ai sets ( measurem5ts1 ea* ( ab\t #bj obs]vations4 ,! rev]b]ation 0 f\nd also by calculation f ,sab9e's equation 7see ,section ,,iii71 tak+ ! volume ( ! ,auditorium z #aa1hjj cubic met]s & calculat+ ! absorb+ p[] ( all ! surfaces 9 ! room4 ,?is calculation gave #f4d seconds4 ,! agreem5t betwe5 ! two results is z close z c\ld be expect$1 s9ce nei!r ! int5sity ( ! s\nd nor ! pit* us$ by ! au?or 0 ! same z ^? us$ by ,pr(essor ,sab9e1 & bo? ( ^! factors affect ! "t ( rev]b]ation4 ,illu/ration3 ,,fig4 #ba4 ,,p>abolic ,,reflector ,,%[+ ,,its ,,action ,,on ,,s\nd4 ,illu/ration3 ,,fig4 #bb4 ,,photograph ,,( ,,p>abolic ,,reflector4 ,sev]al ye>s lat] ! "t ( rev]b]ation 0 aga9 det]m9$ aft] c]ta9 *anges _h be5 made4 ,a ?ick c>pet _h be5 plac$ on ! /age1 heavy vel\r curta9s #ah by #cb feet 9 area hung on ! wall at ! re> ( ! /age1 a l>ge canvas pa9t+ #djj squ>e feet 9 area 0 in/all$1 & ! glass remov$ f ! skylight 9 ! ceil+4 ,! "t ( rev]b]ation 0 r$uc$ to #d4h seconds4 ,) an audi5ce pres5t ?is value 0 r$uc$ /ill m1 & :5 ! hall 0 cr[d$ at comm5cem5t "t ! rev]b]ation 0 n tr\blesome4 ,me?od ( ,elim9at+ ,e*oes4--,al?\gh ! "t ( rev]b]ation 0 r$uc$ to be fairly satisfactory1 z j expla9$1 ! e*oes /ill p]si/$1 & 7 v annoy+4 ,attempts 7 made to r$uce individual e*oes by hang+ cotton flannel on ! walls at critical po9ts4 ,?us ! %ad$ areas 9 ,fig4 #ag 7 cov]$ & also ! entire re> wall 9 ! balcony4 ,pron\nc$ e*oes /ill rema9$1 & x 0 evid5t t "s dra/ic action 0 necess>y to alleviate ?is condition4 ,f\r l>ge canvases1 %[n 9 ,figs4 #bc & #bd1 7 !n hung 9 ! dome 9 position sugge/$ by ! results ( ! diagnosis4 ,a v decid$ improvem5t foll[$4 ,= ! fir/ "t ! e*oes 7 r$uc$ to a m>k$ degree & speak]s on ! /age c\ld talk )\t ! usual annoyance4 ,?is arrangem5t elim9at$ ! e*oes n only on ! /age1 b g5]ally all ov] ! h\se4 ,a numb] ( m9or e*oes 7 /ill left1 b ! conditions 7 mu* improv$1 especially :5 a l>ge audi5ce 0 pres5t to r$uce ! rev]b]ation4 ,propos$ ,f9al ,cure4--,! /ate ( affairs j describ$ is ! condition at ! "t ( writ+4 ,two propositions 7 consid]$ 9 plann+ ! f9al cure4 ,"o proposition involv$ a complete remodel+ ( ! int]ior ( ! ,auditorium4 ,plans ( an int]ior 7 drawn 9 accordance ) ! results ( ! exp]im5tal "w t w\ld probably give satisfactory ac\/ics4 ,?is proposition 0 n c>ri$ out because ( ! exp5se & because x 0 ?\ght desirable to attempt a cure )\t *ang+ ! %ape ( ! room4 ,! latt] plan is ! "o n[ be+ foll[$4 ,x is propos$ to replace ! pres5t unsightly curta9s ) mat]ials :i* w con=m to ! ar*itectural features ( ! ,auditorium & :i* w h a pleas+ color s*eme4 ,at ! same "t1 x w be necess>y to hold to ! features :i* h improv$ ! ac\/ics4 ,illu/ration3 ,,fig4 #bc4 ,,photograph ,,( ,,two ,,( ,,! ,,canvas ,,curta9s ,,9 ,,! ,,dome ,,( ,,! ,,auditorium4 ,,note ,,also ,,! ,,absorb+ ,,mat]ials ,,"u ,,! ,,ar*es4 ,illu/ration3 ,,fig4 #bd4 ,,photograph ,,( ,,dome ,,( ,,auditorium ,,%[+ ,,! ,,canvases ,,in/all$ ,,to ,,elim9ate ,,e*oes4 ,v4 ,,bibliography ,,( ,,publications ,,on ,,ac\/ics ,,( ,,auditoriums4 ,au]ba*1 ,f4 8,aku/ik40 ,w9kelmann's ,h&bu* d] ,physik1 ,vol4 ,,ii1 #aiji4 ,an encyclopdia ( ac\/ics1 ! foll[+ topics apply+ to ! subject 9 h&3 8,aku/ik d] ,gebude10 pp4 #ehj-ehd1 ) ref]5ces4 8,na*hall und ,e*o10 pp4 #efe-efi1 ) ref]5ces4 ,blackall1 ,c4 ,h4 8,ac\/ics ( ,audi5ce ,halls10 ,eng9e]+ ,record1 ,vol4 #de1 pp4 #eda-edb1 #aijb4 ,a pap] record+ ! op9ions ( ! au?or ) _m ref]5ces to ac\/ical prop]ties ( p>ticul> audi5ce halls4 ,cornelison1 ,r4 ,w4 8,! ,ac\/ical ,prop]ties ( ,rooms ,p>ticul>ly z ,affect$ by ,wall ,cov]+s10 #aije4 ,a pamphlet describ+ ! m]its ( 8,fabrikona0 burlap z a s\nd absorb]4 ,h4 ,b4 ,wigg9's ,sons ,company1 ,bloomfield1 ,n4 ,j4 ,ei*horn1 ,a4 8,die ,aku/ik ,gross] ,rame na* ,altgrie*is*] ,!orie40 ,ern/ & ,korn1 ,publi%]s1 ,b]l91 #ahhh4 ,a discussion ( ,greek build+s & ac\/ics1 ) applications to mod]n conditions4 ,ei*horn1 ,a4 8,d] ,aku/is*e ,mas/ab fr die ,projectbe>beitung ,gross] ,inn5 ,rame40 ,publi%$ by ,s*u/] & ,bufleb1 ,b]l91 #ahii4 ,a cont9uation ( ! previ\s "w4 ,exn]1 ,s4 8,ub] die ,aku/ik von ,hrsl5 und e9 ,in/rum5t1 sie zu be/imm540 ,zeits*rift des ,o/]rei*is*5 ,+5ieur und ,ar*itekt5-,v]e9es1 ,vol4 ,,lvii1 p4 #ada1 ,m>*1 #aije4 ,indicates 8 op9ion ( good ac\/ical prop]ties 9 a hall4 ,gives exp]im5tal det]m9ation ( rev]b]ation4 ,f\rni]1 ,luci54 8,! ,suppression ( ,e*oes40 ,la ,nature 7,p>is71 ,april #bd1 #aiji4 ,engli% translation giv5 9 8,! ,lit]>y ,dige/10 ,new ,york1 ,may #bi1 #aiji1 p4 #ibd4 ,an acc\nt ( ! exp]im5ts ( ,gu/av ,lyon 9 inve/igat+ ! e*oes 9 ,trocad]o ,hall 9 ,p>is4 ,frankl91 ,w4 ,s4 8,d]ivation ( ,equation ( ,decay+ ,s\nd 9 a ,room & ,def9ition ( ,op5 ,w9d[ ,equival5t ( ,absorb+ ,p[]40 ,physical ,review1 ,vol4 #af1 pp4 #cgb-cgd1 #aijc4 ,a !oretical developm5t ( ! =mula f\nd exp]im5tally by ,sab9e4 ,haege4 8,bem]kung5 b] ,aku/ik40 ,zeits*rift fr ,baumes51 ,vol4 ,,ix1 pp4 #ehb-eid1 #ahei4 ,h5ry1 ,joseph4 8,ac\/ics ,appli$ to ,public ,build+s10 ,smi?sonian ,report1 #ahef1 p4 #bba4 ,hoyt1 ,j4 ,t4 ,n4 8,! ,ac\/ics ( ! ,hill ,memorial ,hall10 ,am]ican ,ar*itect1 ,vol4 ,,civ1 pp4 #ej-ec1 ,augu/ #f1 #aiac4 ,discusses ! design ( ! hall & indicates h[ x fulfills 8 ideas ( good ac\/ics4 ,hutton1 ,w4 ,r4 8,ar*itectural ,ac\/ics2 ,hall ( ,repres5tatives1 ,u4 ,s4 ,capitol1 #ahec40 ,eng9e]+ ,record1 ,vol4 #db1 p4 #cgg1 #aijj4 ,a discussion ( ! cure ( ! faulty ac\/ics 9 ! ,u4 ,s4 ,hall ( ,repres5tatives4 ,jacques1 ,w4 ,w4 8,effect ( ! ,motion ( ! ,air ,)9 an ,auditorium ,^u ,its ,ac\/ical ,qualities40 ,philosophical ,magaz9e 7#e71 ,vol4 #g1 p4 ,,iii1 #ahgi4 ,a record ( exp]im5ts 9 ! ,baltimore ,academy ( ,music %[+ t ! v5tilat+ curr5t _h a m>k$ action on ! ac\/ics4 ,jag]1 ,s4 8,zur ,!orie des ,na*hals10 ,sitzungsb]i*t5 d] ,kais]l4 ,akademie d] ,wiss5s*aft5 9 ,wi54 ,matem4-naturw4 ,klasse2 ,bd4 ,,cxx1 ,abt4 ,ha1 ,mai1 #aiaa4 ,an important pap] giv+ a !oretical developm5t ( ,sab9e's =mula %[+ ! factors t ent] into ! con/ants4 ,consid]s also ! case ( ! reflection ( s\nd f a ?9 wall & also ! case :5 x enc\nt]s a por\s mat]ial su* z a curta94 ,lamb1 ,horace4 8,! ,dynamical ,!ory ( ,s\nd40 ,publi%$ by ,edw>d ,arnold1 ,london1 #aiaj4 ,a m elem5t>y treatm5t ?an ,rayleigh's 8,!ory ( ,s\nd40 ,m>age4 8,qualites ac\/iques de c]ta9es sailes p\r la voix p>le40 ,comptes ,r5dus1 ,vol4 #adb1 p4 #hgh1 #aijf4 ,an inve/igation ( ! ac\/ical prop]ties ( six halls 9 ,p>is4 ,norton1 ,c4 ,l4 8,s\ndpro( ,p>titions40 ,insurance ,eng9e]+1 ,vol4 #d1 p4 #ahj1 #aijb4 ,an acc\nt ( exp]im5tal te/s ( ! s\ndpro( qualities ( mat]ials t are also firepro(4 ,or?1 ,a4 8,die ,aku/ik ,gross] ,rame mit ,speciallem ,bezug auf ,kir*540 ,zeits*rift fr ,bauwes54 ,also repr9t by ,ern/ & ,korn1 ,b]l91 #ahgb4 ,assumes t s\nd waves behave l light waves4 ,discusses1 ) detail$ draw+s1 ! pa?s ( s\nd 9 ! ,zion ,*ur* 9 ,b]l9 & ! ,nicolai ,*ur* 9 ,potsdam4 ,also gives 8 op9ion ( ! effect ( surfaces & mat]ials on s\nd4 ,rayleigh1 ,"l4 8,!ory ( ,s\nd40 ,two volumes1 ,macmillan1 #ahif4 ,! unsurpass$ classic 9 ! subject ( ac\/ics4 ,ref]5ces to ar*itectural ac\/ics z foll[s3 8,:isp]+ ,gall]ies10 ,vol4 ,,ii1 #bhg4 8,passage ( ,s\nd ,?r\gh ,fabrics10 ,vol4 ,,ii1 p4 #caa4 8,resonance 9 ,build+s10 ,vol4 ,,ii1 #beb4 ,sab9e1 ,wallace ,c4 8,ar*itectural ,ac\/ics40 ,eng9e]+ ,record1 #aijj1 ,vol4 #a1 pp4 #cdi1 #cgf1 #djj1 #dbf1 #dej1 #dgg1 #ejc4 ,publi%$ also 9 book =m & 9 ,am]ican ,ar*itect1 ,vol4 #fh1 #aijj1 pp4 #c1 #ai1 #ce1 #dc1 #ei1 #ge1 #hc4 ,an important s]ies ( articles giv+ ! relation betwe5 ! "t ( rev]b]ation 9 a room1 ! volume ( ! room1 & absorb+ mat]ials pres5t4 ,gives table ( absorb+ p[]s ( sub/ances1 s t an ar*itect c calculate 9 advance ( con/ruction :at ! "t ( rev]b]ation w be4 ,sab9e1 ,w4 ,c4 8,ar*itectural ,ac\/ics10 ,proc4 ( ! ,am]4 ,acad4 ( ,arts & ,sci5ces1 ,vol4 ,,xlii1 ,no4 #b1 ,june1 #aijf4 ,a cont9uation ( ! previ\s "w1 %[+ ! accuracy ( musical ta/e 9 reg>d to ar*itectural ac\/ics & also ! v>iation 9 rev]b]ation ) v>iation 9 pit*4 ,sab9e1 ,w4 ,c4 8,ar*itectural ,ac\/ics10 ,eng9e]+ ,record1 ,vol4 #fa1 pp4 #ggi-gha1 ,june #ah1 #aiaj4 ,discusses ! case ( fl[ ( air 9 a room & its effect on ! ac\/ics4 ,concludes t ! usual v5tilation sy/em 9 a hall has v little effect4 ,sab9e1 ,w4 ,c4 8,ar*itectural ,ac\/ics3 ,! ,correction ( ,ac\/ical ,difficulties40 ,! ,ar*itectural ,qu>t]ly ( ,h>v>d ,univ]sity1 ,m>*1 #aiab1 pp4 #c-bc4 ,an acc\nt ( ! cures ( ! ac\/ical difficulties ( a numb] ( audi5ce rooms1 also a description ( fur!r exp]im5ts on ! absorb+ p[] ( diff]5t mat]ials4 ,sab9e1 ,w4 ,c4 8,!at] ,ac\/ics40 ,am]ican ,ar*itect1 ,vol4 ,,civ1 pp4 #beg-bgi1 ,decemb] #ca1 #aiac4 ,describes !at] ) model ac\/ics4 ,discusses behavior ( s\nd 9 a room & %[s photographs ( s\nd waves 9 m9iature rooms4 ,sab9e1 ,w4 ,c4 8,ar*itectural ,ac\/ics4 ,build+ ,mat]ial & ,musical ,pit*40 ,! ,brickbuild]1 ,vol4 #bc1 pp4 #a-f1 ,janu>y1 #aiad4 ,a cont9uation ( previ\s "w1 describ+ absorb+ p[]s ( diff]5t mat]ials4 ,%>pe1 ,h4 ,j4 8,reflection ( ,s\nd at a ,p>aboloid40 ,camb4 ,phil4 ,soc4 ,proc41 ,vol4 #ae1 pp4 #aij-aig1 #aiji4 ,/ew>t1 ,g4 ,w4 8,ar*itectural ,ac\/ics40 ,sibley ,j\rnal ( ,eng9e]+1 ,may1 #aijc4 ,publi%$ by ,cornell ,univ]sity1 ,i?aca1 ,n4 ,y4 ,an acc\nt ( an inve/igation lead+ to ! cure ( ! ac\/ics ( ,sibley ,auditorium4 ,/urmhfel1 ,a4 8,aku/ik des ,baumei/]s40 ,publi%$ by ,s*u/] & ,bufleb1 ,b]l91 #ahid4 ,an #hg-page pamphlet on ! ac\/ics ( rooms4 ,discusses effects ( relief "w 9 rooms on s\nd4 ,acc\nt ( exp]im5tal "w4 ,ref]5ces to auditoriums4 ,tallant1 ,hugh4 8,h9ts on ,ar*itectural ,ac\/ics40 ,! ,brickbuild]1 ,vol4 #ai1 #aiaj1 pp4 #aaa1 #aee1 #aii1 #bdc1 #bfe4 ,a s]ies ( articles giv+ an exposition ( ! pr9ciples ( ! subject ) practical applications4 ,tallant1 ,hugh4 8,ac\/ical ,design 9 ! ,hill ,memorial ,auditorium1 ,univ]sity ( ,mi*igan40 ,! ,brickbuild]1 ,vol4 ,,xxii1 p4 #afi1 ,augu/1 #aiac4 ,see also plates #aac1 #aad1 #aae4 ,a discussion ( ! ac\/ical results obta9$ 9 ?is auditorium1 a special feature be+ ! action ( a huge p>abolic reflect+ wall surface ov] ! /age4 ,tallant1 ,hugh4 8,ar*itectural ,ac\/ics4 ,! ,effect ( a ,speak]'s ,voice 9 ,diff]5t ,directions40 ,! ,brickbuild]1 ,vol4 #bb1 p4 #bbe1 ,octob]1 #aiac4 ,taylor1 ,h4 ,o4 8,a ,direct ,me?od ( ,f9d+ ! ,value ( ,mat]ials z ,s\nd ,absorb]s40 ,physical ,review1 ,vol4 #b 7#b71 p4 #bgj1 ,octob]1 #aiac4 ,tufts1 ,f4 ,l4 8,transmission ( ,s\nd ,?r\gh ,por\s ,mat]ials40 ,am]4 ,j\rnal ( ,sci5ce1 ,vol4 ,,ii1 p4 #ceg1 #aija4 ,exp]im5tal "w lead+ to ! conclusion t s\nd is transmitt$ ?r\gh por\s mat]ials 9 ! same proportion t a curr5t ( air is4 ,watson1 ,f4 ,r4 8,e*oes 9 an ,auditorium40 ,physical ,review1 ,vol4 #cb1 p4 #bca1 #aiaa4 ,an ab/ract giv+ an acc\nt ( ! exp]im5ts 9 ! auditorium at ! ,univ]sity ( ,ill9ois4 ,watson1 ,f4 ,r4 8,ineffici5cy ( ,wires z a ,means ( ,cur+ ,defective ,ac\/ics ( ,auditoriums40 ,sci5ce1 ,vol4 #ce1 p4 #hcc1 #aiab4 ,watson1 ,f4 ,r4 8,! ,use ( ,s\nd+ ,bo>ds 9 an ,auditorium40 ,physical ,review1 ,vol4 #a 7#b71 p4 #bda1 #aiac4 ,also a m complete article 9 ,! ,brickbuild]1 ,june1 #aiac4 ,watson1 ,f4 ,r4 8,air ,curr5ts & ! ,ac\/ics ( ,auditoriums40 ,eng9e]+ ,record1 ,vol4 #fg1 p4 #bfe1 #aiac4 ,a detail$ acc\nt giv+ !ory & exp]im5tal "w1 ) application to v5tilat+ sy/ems 9 auditoriums4 ,watson1 ,f4 ,r4 8,ac\/ical ,effect ( ,firepro($ ,cotton-,flannel ,s\nd ,absorb]s40 ,eng9e]+ ,news1 ,vol4 #ga1 p4 #bfa1 ,janu>y #bi1 #aiad4 ,results ( exp]im5ts %[+ t cotton-flannel has practically ! same absorb+ p[] aft] firepro(+ z be=e4 ,weisba*1 ,f4 8,v]su*e b] ,s*alldur*lassigkeit1 ,s*allreflexion und ,s*allabsorbtion40 ,annal5 d] ,physik1 ,vol4 #cc1 p4 #gfc1 #aiaj4 ,williams1 ,w4 ,m4 8,e*o 9 ,alb]t ,hall40 ,nature1 ,vol4 #c1 p4 #dfi1 #ahgj-ga4 ,obs]vations on ! %ape ( ,alb]t ,hall 9 ,london & ! e*oes set up4 ,editorial ,notice4 8,! ,dresd5 ,laboratory = ,ar*itectural ,ac\/ics40 ,am]ican ,ar*itect1 ,vol4 #ajb1 p4 #acg1 ,octob] #af1 #aiab4 ,/ates t a laboratory ( appli$ ac\/ics is au?oriz$ 9 ! ,dresd5 7,g]many7 ,te*nis*e ,ho*s*ule1 & t exp]t advice w be furni%$ ar*itects & o!rs reg>d+ problems ( ac\/ics ( auditoriums4 ,,! ,,univ]sity ,,( ,,ill9ois ,,! ,,/ate ,,univ]sity ,urbana ,,edmund ,j4 ,,james1 ,ph4 ,d41 ,,ll4 ,d41 ,presid5t ,! ,univ]sity includes ! foll[+ dep>tm5ts3 ,! ,graduate ,s*ool ,! ,college ( ,lib]al ,arts & ,sci5ces 7,anci5t & ,mod]n ,languages & ,lit]atures2 ,hi/ory1 ,economics & ,acc\ntancy1 ,political ,sci5ce1 ,sociology2 ,philosophy1 ,psy*ology1 ,education2 ,ma!matics2 ,a/ronomy2 ,geology2 ,physics2 ,*emi/ry2 ,botany1 ,zoology1 ,entomology2 ,physiology2 ,art & ,design2 ,c]amics7 ,! ,college ( ,eng9e]+ 7,ar*itecture2 ,ar*itectural1 ,civil1 ,electrical1 ,me*anical1 ,m9+1 ,municipal & ,sanit>y1 & ,railway ,eng9e]+7 ,! ,college ( ,agriculture 7,agronomy2 ,animal ,husb&ry2 ,dairy ,husb&ry2 ,horticulture & ,l&scape ,g>d5+2 ,vet]9>y ,sci5ce2 ,agricultural ,ext5sion2 ,tea*]s' ,c\rse2 ,h\sehold ,sci5ce7 ,! ,college ( ,law 7,?ree ye>s' c\rse7 ,! ,s*ool ( ,education ,! ,c\rses 9 ,bus9ess 7,g5]al ,bus9ess2 ,bank+2 ,acc\ntancy2 ,railway ,adm9i/ration2 ,insurance7 ,! ,c\rse 9 ,j\rnalism ,! ,c\rses 9 ,*emi/ry & ,*emical ,eng9e]+ ,! ,c\rses 9 ,c]amics & ,c]amic ,eng9e]+ ,! ,s*ool ( ,railway ,eng9e]+ & ,adm9i/ration ,! ,s*ool ( ,music 7f\r ye>s' c\rse7 ,! ,s*ool ( ,libr>y ,sci5ce 7two ye>s' c\rse7 ,! ,college ( ,m$ic9e 79 ,*icago7 ,! ,college ( ,d5ti/ry 79 ,*icago7 ,! ,s*ool ( ,ph>macy 79 ,*icago2 ,ph4 ,g4 & ,ph4 ,c4 c\rses7 ,! ,summ] ,session 7eight weeks7 ,exp]im5t ,/ations3 ,u4 ,s4 ,agricultural ,exp]im5t ,/ation2 ,eng9e]+ ,exp]im5t ,/ation2 ,/ate ,laboratory ( ,natural ,hi/ory2 ,/ate ,entomologi/'s ,(fice2 ,biological ,exp]im5t ,/ation on ,ill9ois ,riv]2 ,/ate ,wat] ,survey2 ,/ate ,geological ,survey2 ,m9e ,rescue ,/ation ,! libr>y collections conta9 7,may #a1 #aiad71 #bie1jjj volumes1 includ+ ! libr>y ( ! ,/ate ,laboratory ( ,natural ,hi/ory1 ! ,qu9e ,m$ical ,libr>y & ! libr>y ( ! ,s*ool ( ,ph>macy4 ,= catalogs & in=mation address ,,! ,,regi/r> ,urbana1 ,ill9ois ,,footnotes #a 8,!ory ( ,s\nd10 ,vol4 ,,ii1 p4 #caf4 #b 8,!ory ( ,s\nd10 ,vol4 ,,ii1 #cea4 #c 8,dynamical ,!ory ( ,s\nd10 p4 #aif4 #d 8,!ory ( ,s\nd10 p4 #ccc4 #e 8,ar*itectural ,ac\/ics40 ,a s]ies ( articles 9 ! ,eng9e]+ ,record1 #aijj2 also ! ,am]ican ,ar*itect1 #aijj4 #f 8,ar*itectural ,ac\/ics10 ,proc4 ( ,am]4 ,acad4 ( ,arts & ,sci5ces4 ,vol4 #db1 pp4 #di-hd1 #aijf4 #g ,g4 ,w4 ,/ew>t4 8,ar*itectural ,ac\/ics10 ,sibley ,j\rnal ( ,eng9e]+1 ,may1 #aijc4 ,publi%$ by ,cornell ,univ]sity1 ,i?aca1 ,n4 ,y4 #h 8,qualits ac\/iques de c]ta9es salles p\r la voix p>le40 ,comptes ,r5dus1 #adb1 #hgh1 #aijf4 #i ,w4 ,s4 ,frankl94 8,d]ivation ( ,equation ( ,decay+ ,s\nd 9 a ,room & ,def9ition ( ,op5 ,w9d[ ,equival5t ( ,absorb+ ,p[]40 ,physical ,review1 ,vol4 #af1 pp4 #cgb-cgd1 #aijc4 #aj ,g4 ,jg]4 8,zur ,!orie des ,na*halls40 ,sitzungsb]i*te d] ,kais]li*e ,akad4 d] ,wiss5s*aft5 9 ,wi51 ,ma?-naturw4 ,klasse2 ,bd4 ,,cxx4 ,abt4 #aa a4 ,mai1 #aiaa4 #aa ,sci5ce1 ,vol4 #ce1 p4 #hcc1 #aiab4 #ab ,ar*4 ,qu>t]ly ( ,h>v>d ,univ]sity1 ,m>*1 #aiab4 #ac ,osborne ,reynolds4 ,proc4 ( ,royal ,soc41 ,vol4 ,,xxii1 p4 #eca1 #ahgd4 #ad ,joseph ,h5ry1 8,report ( ! ,ligh?\se ,bo>d ( ! ,unit$ ,/ates = ! ye> #ahgd40 ,j4 ,tyndall1 ,phil4 ,trans41 #ahgd4 #ae ,sab9e1 ,eng9e]+ ,record1 ,vol4 #fa1 p4 #ggi1 #aiaj4 ,watson1 ,eng9e]+ ,record1 ,vol4 #fg1 p4 #bfe1 #aiac4 #af ,sab9e & ,watson4 ,ibid4 #ag ,la ,nature 7,p>is71 ,april #bd1 #aiji4 #ah ,rayleigh 8,!ory ( ,s\nd10 ,vol4 ,,ii1 #bhc4 #ai ,rayleigh1 ibid1 #bhc4 ,transcrib]'s ,notes ,punctuation1 hyph5ation1 & spell+ ( ,engli% words 7 made consi/5t :5 a pr$om9ant pref]5ce 0 f\nd 9 ! 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