attention and the perception of speech

8/11/2019 Attention and the Perception of Speech

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TTE TIO AND THE PERCEPT O OF S E H

Ifan individual listens to o VOIce mess ges t one i e, he

u a y understa ds o o e. T i i di a es t a the b a haan "atten io e isI o selec n t e desi i fo mation

P ing tte tion nd not p ing attention a e u el two of the mo timportant abilitie of hum n beg . Yet in pite of their cr c l role ining, d in a ho t of oth r int lligenttivit e , s chologi t fo m n si not conside them p o e to cs ofs ud . ttention eemed ub ct e

lit , as oc ted hi to c ll it thtrospective method o nv stig tion.t method ten s to g v ncons st nt

esults n so f ll into dis ute mongr me t l ps chologists. Co r spond

g , most pectable th o st i d tom e u e o n concept s mb ng t-t ntion; nd, since e e rch n ps chol-og t nds to be omin b theor ,t ere w s little e p im t tion ongl n s t at m ght h ve r v v d th i e .

n the st 0 e s, owev r, tcon t of tt nt on h s b gun to o ci self on the ttention of ps cho ogi tsin v ou w . ne i th ough studieo the e cienc of control s st ms s chs thos concerned with h regul ionof ai tr c t ai port . m or c se ofilu e in th se s stem s t t th h m n

o er to too much info m t on toh ndle mult neousl , or th t he r ctto an unimport nt s gn l when he should

be dealing w h n import nt one. Th seoblem require some und rst n ng ofhenomena that would common be de-

sc ibed unde the head ng of attent on.The e is now ccumul ting idevariet of experimental esult th tl rif the e phenomena, lthough thel ge part of the wor ema ns to beone. In thi article I shall de cr be someo the rese ch on ttent on to spo nm s ages.

ne of the e rlie t n ngs, a d onethat agre with ever da experienc , th t t i h de to unde tand two mes-s ge arriving imultaneousl than t omes age ar ving one fte the othe .

b b

ne m ght b tempted to explain th pu l h ic l interference betwe nthe t o t mul ; fo ex mple, th loudes age of one me age m ght d ownt the softe p sage of the other ndce er , r n er ng them both unin

t lligibl . ctu ll t e matter s not sosimpl . reco ding the me age ont p nd pl ing them fo d erent bct i st ucted to re pond in d erents, th intell gibilit i shown to de-

nd on p chological f ctor . Speci c ll , ith m s age become unde t nd-le i th l st n r s nst ucted to ignore

th oth r. t the two mes ge togethennot both be un er tood, even though

th necess r information is available toh . not e wa of ma ing the s meoint is to i rt the wo d of one m -s g into s ce between the word fromthe oth h God s ave can o r oug cio s ee Queen. Each me ge ih d to nder t nd, but each wo d is o en s atel nd i ll udible.The di cult evidentl lies in ide t en rvous s st m, w ich omehow re-nt an dequ te re ponse to sign l

t t a e h rd ti f cto il .

Fther e pe iment demonstr t th t

com ehens on mprove if the twom ssage di er in ce tain ph c l ch rct rist c . For in tance, i s better f m n pe one me age and womans e s th ot er; or if the loud pea ermove the lower tone from one voice

b t not the other. Spatial separ tion othe t o vo ce give the best e lt of ll.The di erent mes age should not comethrough th ame loud pe er o evenom sep r te spe ers mounted oneove the other; the two spea er should

b p rated a fa a po sible f om e chothe in the hor zontal pl ne. Inte e t-ngl enough, a l tene al o compre-hend multaneou po en m ss ge

bett when the come from a tereo-phon c tem than when e rela e ove a ingle u p a ( i

e ect, ather than the doub fu gain neali m, i fo man eopl the ma ndvantage of tereophonic h gh elits stem : the li tene can pa a tentionto d e ent mu cal in t umen la et the me t me.

Ph ical di tinct on a e mo t helpfulin p omoting unde t nd ng wh n onem s age h no mpor ance f the lis-tener nd doe not have to be an we e .It would eem that the di er nce allohe brain to lte he incoming undsnd elect ome fo e pon e wh le gnong others.

The need to thro awa pa t of thev il ble in ormation c n p hap be un-

tood b compar ng t e b ain withm n made communicat on tem . En-gineer nowada tal of ca acit fot n m tting info mation, b which t emean the numbe of e uall robableme age of which one c n be ent in speci d time. Suppo e, for ex mple,t t two compl cated militar pl n havebeen prepare and an o de s t beent to car out one of them. A implecommunication tem con i ting of

ed nd a green lamp can t an m t theme age with maximum e cienc b thelight ng of a ingle lamp. If the e e efou plan in tead of two, however, itwould be im o ible to give the der bligh ng one of the two lamp no matterhow imple each plan might b . Eitherthere mu t be mo e amps or mo e time

needed fo ending the orde . In themo t e cient code for two lamp , twos cces ve Ra he o the ed lamp woulmea one plan, a ed R h followe b g een Ra h would mean anothe , and oon One of fou o ible mes age can bet an mitte with two l mp , but o l bt i g two un t of time. W th e ght pos

1962 SCIENTIFIC AMERICAN, INC


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EARDRUM

SE I IRCU AR

WINDOW

SCALAVEST B LI

S S VEC LLS

BAS ARM MBRANE

ERVE

- \N I

BAS LARM MBRANE

SCA A YMPANI

AUDITORY N RVE

PERCEPTION OF SPEECH b g s n h shown op ns mpl d c oss s on. Th a d um nsm s sound v b ons o

h sm ll bones ll d oss s wh h aus w v s n u d nh o l . Th o hl , s n n c oss s ion t bo om l f , onns he b s l m mb n (colo ), on wh h s h s ns v

144

O ALW NDOW

ROUNDWINDOW

ce ls a xc ud o y n v b s. A bot om r o soll d o u , h bas la m mb an n s d v w. F ont v o hb s l m mb n (bottom right) shows h s w d onnd han h o h Th w d g o v b at s n espons o low qu n s, wh s h n ow g on sponds o h gh qu n i s.



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t on to more than one. When the liste eris thoroughly familiar with sit ation,so that he knows to within a small num-r of alternatives what each message

will be, he can comprehe d two sim lneo s mess ges. But when one or othessages re rawn from a large numb rof ossibilities, the lter in the br i letso ly one message com through.

ow does the lt r work? As yet theanswer is not known. Eno gh is

known, however, about he physicalc aracteristics of speech and the phys-i ogy of hearing to make possible somer asonable speculation. Hum n s echis produced by the combined ction oft e vocal cords and the vocal tr ct,w i h consists of the cavities of the

at, mouth an nose. Taut vo al cordsproduce a buzz wh n air is forcedt ro gh them. The b zz consis s of brieflses, r pu s of air, at the r te of 0r more per second, each pulse cont iing nergy at many frequencies. T esls s xcite into vibration the ir in t e

c viti s of the throat, nose and mT e cavities c n be t n d to di erentfr quenci s by changing t e osi ion oft e tongue, cheeks, jaw nd lips W temerges is a train of waves th t co i sa rticular group of frequenci s n isls d about 100times pe second. lse starts out at full stre gt d -ys rapidly until the so nd energy is r -

ewed by the next one [ - ]Many vowel sounds cont i w v s t

two or more widely s para d freq n-i s For ex mple, when the gre testn rgy is at 375 and ,700 cycles rs c d, the vowel so nd in the worit" is produced frequencies f 50

nd ,700 cy les per second giv thevowel in bet. ( hese gures ap ly to ty i al male voice. In the voic s ofwomen and children the whole ange offr que cies may be higher but t e lis-te er takes this into ccount.) On ach-ing the ear, the soun s stimul te s s eorg ns arranged long the basila embran in th cochlea on 144] Low frequencies sti ulateorgans at one nd of the membrane highfrequencies ect those at the othe end.A complex sound m de up of sever l free ci s en rgizes s ve al i ere t e

gions of the basilar membrane. Eachsense org n on the membrane co tsith rticular nerve bers going o the

br in; t s the wo d bit" stimulat s oneom ina ion of bers and the word b t"other combination.

If both words reach the ear sim t nesly, oth combinations of bers o ld

com into play and the brain woul havet e problem of deciding which elongt t er t might seem then th t twor ore voi s wo ld prod ce so monf sion in the ear that the brain co lot sele t one voice for special ttenion f cou se, certain obvious f turesl disti guish o e speaker fro aher: ccent, rate of speaking, 10 dness

or softness B t one cannot mak se ofthese features ntil one knows hicfrequencies long to which voice Thuse ro lem rem ins: How do s th

r in ma age to focus attention onevoice? St di s of the arti cial g n rationof speech sounds have egun to throwsome light on this problem.

Peter Lad foged of the Univer ity oEdinburgh and I have been experment-n with a device th t was develo ed yW lte L wrence of e Signa s

L F L ER FR Q E CY

H GH F L ER FRE C

SPEECH SO DS co sist of p ses of e -e f om t e voice, s ow e e as i a d

se r Develo m nt Establishment iEngl nd O r version of the ppa t ssends series of electrical pulses ( n lo

gous to puls s from the voc l cords)thro gh two lter circuits, each of whichpasses primarily one frequency. Thewaves from one lte circuit, which arelike thos from the largest hum n spee hc vity, are mixed with waves from theother, which imitate the requencies prod ced by th second larges cavity To

D E E E EQUE C ES same ate of p lsatioo mod latio f om voice e ites two di e e t e io s of a basia mem a e ( t) iste e epo ts e ea s o e vowel so nd

FFE E T P SA IO ATES a d di e e t te f e ees make t e liste e ea two di e e t o ds eve t o o

one a o basila memb a e s a t a ei sed fo ea i _

4 1962 SCIENTIFIC AMERICAN, INC


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O MODU O GH MODU O

ow o ulat o c o o a o pe reque c e e ted the outh a throat " lter or av t e he e tw

pe o wave o b e pa ter l e tho e th a aE ect o u h wave are how a ro botto o the e two a

gether the two wave trains are heard asquite ac eptable vowel sounds that canbe changed by tuning the te s to di

ferent requencies. Varying the pu serate used to excite the lters alte she apparent pitch o intonation o thespeech": it ises with faster pulse atesand falls with slower ones.

hen the same pulses excite both l-ters a istener hears the output as eadilyidenti ab e vowel sounds. This is t ue

even when the lo frequ ncy is ed intoone ear an the high requency into theoth r B t i th two lte s are pu sed at

s ightly i rent at s the spe h" be-omes una epta e and listeners saythat they are hearing t o sounds comingrom two sources ather than a sing evowel sound

Other xper ments on the fusion of

sounds at the two ears onducted yolin A herry and his oll agues at

the mperial ollege o S ience and

Technology in London a so s pport t ei ea that when the r te o pulsing ormodulation is the same or two soundsthe hearer perceives them as one soun .t seems reasonab e to sup os thereo e that a m n can listen to one person

U I G BO H E , l te er w l hear o e vowe ou thou h r ht ear hear o e lter requ nc a le t ear earsa ot e he pul at o or mo ulat o rate ha to be the a e

TW TIO ES, co b e w th a e lter requeand f d nt each ar eparatel , pro u e t o t ct ouhe bra ev e 1 l ocu e t atte t o o t ate o ul at o



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and igno e anothe p ima i y by se ecting f o he mass of sounds ente ing hisea s a those f e uencie tha a e beingmodu ated at the sa e ate Since i imost un ike y tha the voca co ds of twospeake wou d vib ate at exact y thesame ate a any oment modu ationwou d a mo t a ways p ovide an impoant (if not he so e) ean of sepa atinga pai of voice

I is now a gene a y accepted p incip e of neu ophysio ogy that messages

"BE

B T

BOUGH

t ave ing a ong a pa ticu a e ve candi e eithe by invo ving di e ent ne vebe s o by p oducing a di e ent umbe of impu ses pe econd in the be s. High f e uency and ow f e uencyound stimu ate di e ent be s. It may

be that the ate at which the sounds a epu sed cont o s the ate of ing of thebe s. f so, the b ain cou d pick out oneoice f om othe s by focusing its attention on a a dito y ne ve be s that a eing at the same ate

A fu the indication of the impo ancof modu ation is that it a he a hef e uency of the waves being oduated, seems unde ce ain condition todete mine he pitch of a voice This canbe demonst ated wit the a i ciaspeech gene a o A te tuned to say3 000 cyc es pe econd i pu sed at theate of 100cyc e pe econd A isteneis a ked to matc the pitch of the soundwith eithe of two simp e sound wavesone at 100cyc e pe second and the oth

T

SO D S ECT OG MS ho tha a iou o e ou d a emade of e e a di e e f eque cie Time i ho ho izo a yque ie e ti a y a d i te ity o ou d by e ati e da k e

The "b of ea h o d a ea a o e t eque y Vo e be i

sudd enl y as ips ope n . After vow el th er is a quie pe r iod o o we d

b y a bu st of nois e p im ar il y at hig h f eq ue n cy as h e " ex pl od es .Fr q ue nc y sh ifts in "b ate an d "b i e ar e di pht ho ng s. S pe c t rog am s we e ma d e b y H. K . Du n o f Be ll Te le pho n e L abo a torie s



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Califor i Institute of Tech ology; Case I stitute of Technology; University of Chicago; Columbia iv rsity

M ssac usetts Institut o Techno o y; U iversity o Mic i an; Pennsy ni St te Uni ersity; St ord University; Tulane University

High BridgeThe Department of Defense is required t make hundred f deci i ns daily that a ect the well-being and securityof ever one of us. It m st ave the highe t ible quality of technical advice before making ts far reachingand consequentia de s ons * For one major source of su h advice, the Department has turned to the In tituter Defense Ana yses a on pro t corporate entity spon red by nine great iversities. The In titute ha aemb ed a sta from e nationa source of rofe si nal ta ent fr m indu tr , fr m research and deve o mentlaboratories fro un versity facu ties an graduate circ es. * Thu A is a bridge between two w rlds, heDepart ent of Defen e o one si e and the academi an pr fe si na scienti c c mmunity n the other. n erving as a r dge for tra of ideas an recommen tions n maj r nation l r blem A c ntribute t hedeve op ent of e im ediate and future po ture f ur nati na ecurity. A em l articularly t lented in i

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IDA



8/11

General Mills P oneers New Techn q ues:In Gear Miniat rization ... Ball on Launc g

Miss le programs have set o an unprecedented In coope at on with the Navy, Gene al M ll develsearch for ays to "shrink components. Gears and o d a n w m thod of launch ng high al tudear packages have been acute trouble-spots. Con- balloons from smal sh s Prev ous me hod r

ve tio a ear min iaturization techniques ut ze u d larg x an o ca e d ec T n wra ne pit hes. General Mi s took an entirely tec n qu qu e dec s ace fo loa

new ck: deve oped a rad cally new system of tooth launc ng equ p ent only T alloon m di ati . iny involute spur p nions having as on t e water surface a t ern o e e as 4 eeth have bee g nerated ith conven Lau c ng and co e y se ce a ju a i a hobs res ti g in higher ratios per mesh com l e alloon ac a O e e c nc uoarser p tches, and fe er of the manufacturing and e cle de gn a d nufac u , c en c n unspec on problems i herent in ultra- n p tches. n a on, com un c on n da uction

Write today for a copy of our concise bookle : "Bro Spectrum Cap bi ities to Serve the Ae osp e ge.

EL CTRONICS GROUP620 Central Avenue Minneapo lis 3, Minne t

15 1962 SCIENTIFIC AMERICAN, INC


9/11


10/11

ANN N N The International Co gress o Diamo ds n Industrysponsored by the Diamond Research Lab ra ory will ake p ace in Par s,Fra ce, a the Pa ais de la D fe se, from May 2 o Ju e . Lates advancesi use f dust al diamonds ll be demo s ated, and a sympos um

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o e Spe y oscope o ses a a a o s o s ace scoppe plated alu inu me o y s o co p e s a ia io s emi o finis do o no mally excee 20 o s a c Fi al s faces now produc d n as many min tes as ould a e aken ou s y t eo e gri ndi ng p c .

ig t Natu a d am nd impr gnat d ones inis g nd cy inde wal fa ma r ur p an aut mobi manufactu . m ta b nd n avesu t d in ry l ng p duction uns-f m 40 00 t 6 cylin r aveen mac n d w t a ng t of n

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The e manufac ure are u ng na u al a ono a van age Yo ca , oo

he grinding and polishing jobs s ow re areerformed in compl t ly d r nt industri s. Buthey hav one importa t thing in commo : iery cas , atural diamonds are doi g the jobu ckly-and economically.Diamonds o r th s u ique combinatio of

roperties excellent cutti g a i y l ked han astic enduranc Your diamond too s astong r than a y oth r too s. You peo e spend

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usi ess, you ca e t ra

t advantag st th m agains you prese tm thod You' f nd out how e cient-an economica - diamond ca b .Bes et l-b d eels de el ped yD d ese c L b y J esbu A ne mpact crush ng e hod fo natura diamonds s now p oduc g the strongest a d mostdura le diamon g it e obtained for metalbond whee s You too a d whee a fac uris ead e y select the a ha g r

Ab e h eeke ( ) 8lm spoo m d f t prec e e aing operat o . he Mach ne Shop theKodak Park Wo ks of East a K ak Coma y, Rochester, N Y uses natu al d amonm cron powder a oil paste o this decat is i g op rat o

Left: Vascoloy Ram t Corp aukegan, III.,grinds w ar resistant part for the o l indusy wit vitrif ed bond wheel uti izing 100

m sh natural diamond Carbide s 505grad Roc well, 9 A hardn ss. Grinder remov s 00 " to 0 5" of mat rial on achpass or a totaI of 0 2" to 0 5". Nat raI

amo ds provid t o l satisfac orym t od fo t i s ob

ndustrial diamonds cut p act c y eve yth ng ... esp c all y you p od ct on co t

15 3

attention and the perception of speech

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