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An investigation of speaker height and Weight Discriminations by means of paired comparison judgments
Journal of Phonetics (1980) 8, 205-212.
An investigation of speaker height and Weight Discriminations by means of paired comparison judgments Norman J. Lass* , George W. Brong, Sharon A. Cicco lelia, Sandra C. Walters and Ellen L. Maxwell Speech and Hearing Sciences Labora to ry, West Virginia Un iversity , Mu•;;.:rntown, West Virginia 26506 , U.S.A. R eceiPed 4th September 1978
Abstract :
T he p urpo se of this inve stig atio n was to determine if listeners were capab le o f making accurate comparative judgments of speakers' heights and we ights when presented with pairs of recorded speech samp les. A stan d a rd prose passage was reco rd ed by 18 speake rs, nine fe m ales and nin e mal es. Two mast e r tapes were constructed , o ne for eac h speaker sex. A paired co mp ar iso n procedure was employed in the preparation of th e tapes, so that eac h tape co ntain ed a total of 36 pairs o f read in gs [ n(n -1 )/2 1. The readings in eac h pair co nsisted of the third se nt ence from the speak e rs' re cordings of the standard prose passage. The ma ster ta pes were pl ayed to a gro up o f 40 judges, 20 females and 20 ma les , fo r height a nd weight discrimination judgments. All liste ne rs parti cipat ed in tw o sessions, one for h e ight a nd one for weight judgments. They were asked to jud ge which m ember of eac h pair was heavi er or t a ll er as well as the co n fid ence of eac h d ecisio n o n a seve n-point confidence rating scale. Resu lts o f their judgme nt s indi cate that li steners are capa ble of mak in g accurate discr imin ations of speake rs' height s and weights a t bett e r than chance-guessing leve ls. Moreove r, th e sex of th e speake r a nd li st ene r did not signi fica ntly affect he ight and weight judgme nts . Im p li cations of th ese find ings and sugg estion s for future re searc h are discussed .
ln~roduction
Contemporary resear ch o n speaker identification has also included the study of speaker heig ht a nd we ight ide ntificatio ns. In addi tion to speaker age (Ptacek & Sander , 1966;Shipp & Ho lli en , 1969 ; Ryan & Burk , 1972; Burk et a!. ; 1975; Hartman & Danhauer, 1975) , sex (Schwartz, 1968; Schwartz & Rin e , 1968 ; I nge ma nn , 1968 ; Co leman , 197 1 , 1973a, b; Abrams , 1973; Lass eta!. , 1976; Lass et a!. , 1979), race (Stroud , 1956 ; Hibler , 1960 ; Di c ken s & Sawye r , 1962; Larson & Larso n , 1966; Bryden , 1968 ; Alvarenga, 1971 ; Abrams, 1973 ; Lass ct al. , 1979) , socioecono mi c status (Harms , 1961, 1963) , personalit y (Stagner , 1936: Eise n berg & Zalowitz, 1938 ; Markel , Eisler & Reese , 1967) , spe cific identity (McGehee , 193 7 ; Pollack , Pickett & Sumb y, 1954 ; Co mpton , 1963; Vo iers , 1964; Clarke , Becker & Nixo n . 1996 ; Bricker & Pruza nsky , 1966; Ho lmgren, 1967; Stevens et al. , 1968; Cia rkc & Bec ker , _1969: Co lem an , 1973c) , and fac ial a nd bodily featu res (Lass & Harvey,
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N. J. Lass et al.
1976) , listeners have also been found to be capable of speaker height and weight identifications with better than chance-guessing accuracy. In a study by !...ass & Davis (1976) , listeners were given a multiple-choice respon se task for their height and weight judgments. Four choices were provided for each speaker. For height judgments , the choices were : (a) under 5'0" ; (b) 5'0"-5'5"; (c) 5'6"-6'0" ; and (d) over 6'0". For weight judgments, the choices were (a) under 100 lb; (b) 100-150 lb; (c) 151-200 lb; and (d) over 200 lb. Results indicated that listeners were capable of accurately identifying the heights of male and female speakers and the weights of male speakers at better than chance levels. In a second study , Lass et al. ( 1978) attempted to determine if listeners were also capable of the more demanding task of making direct estimations of speakers' heights and weights from recorded speech samples, without the use of multiple-choice responses . It was found that listeners were capable of accurately identifying the approximate heights and weights of speakers at ·better than chance levels , and that th e sex of the speaker and listener did not significantly affect speaker height and weight judgments. The purpose of the present investigation was to determine if listeners were also capable of making accurate comparative judgments of height and weight when presented with pairs of recorded samples of speakers' voices. Method
Speakers A total of 18 speakers, nine females and nine males , participated in the study. All were students at West Virginia University with normal speech characteristics and no reported hearing difficulty. The heights of all speakers were obtained by usin g a tape measure attached to a wall ; the speakers' weights were obtained from a standard floor scale . The same tape meas•.ue and scale and identical measurement procedures were employed for height and weight determinations for all speakers in the study. The range of heights was 57- 75 in for females and 63- 80 in for males. The range of weights for females was 92-220 ib, and 115-200 lb for males. · Construction of master tapes The speakers' readings of the first paragraph of Fairbanks' (1960) The Rainbow Passage were recorded in a sound-treated room using an Ampex model 602 tape recorder and an Altec model 681 A condenser microphone . A total of two master tapes were constructed, one for female speakers and one for male speakers. A paired comparison proced ure (Guilford , 1954) was employed in the preparation of the tapes. Each tape contained 36 pairs of readings [n(n -- 1)/2], with each of the nine speakers ' readings appearing eight times on each tape. The readings employed in each pair consisted of the third sentence of the recorded passage, which was electronically extracted from the original recording . For both tapes , the o rder employed for presentation of the pairs of readings as well as the order for the memb ers of each pair was developed for paired comparison tasks by Ross (1934) to avoid time and space errors. A one-second pause was inserted between the two recordings in each pair , and a seven-second pause was inserted between each pair to allow sufficient time for listener judgments. In addition to the 36 pairs of readings , each tape included five pairs to be judged for practice purposes . Therefore , each tape contained a total of 41 pairs of readings . Both master tapes were constructed by means of electronic reproductions of the speakers ' original reco rdings. All reproductions were made using high-quality recording equipment in the Speech and Hearing Sciences Laboratory at West Virginia University . Experimental sessions A total of 40 judges, 20 females and 20 males , participated in th e st udy. All were students at West Virginia University and reported no hearing difficulty. The judges were unfamiliar
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with the speakers on the master tapes, as determined by their responses to a list of names of the speakers prior to their participation in the study. The judges participated in a total of two sessions, one for height judgments and one for weight judgments. In each session the listeners heard both the male and female tapes. The order of presentation of the height and weight discrimination tasks was randomized so that 20 subjects (10 females and 10 males) made height judgments in the first session and weight judgments in the second session , while 20 subjects (1 0 females and 10 males) made weight judgments in the first session and height judgments in the second session. In addition, the order of presentation of the male and female master tapes in each session was randomized. In all experimental sessions , the listeners heard pairs of speakers' recorded readings and were asked to judge which member of each pair was heavier or taller. In addition, they were also asked to indicate the confidence of each of their judgments by means of a seven-point confidence rating scale (Coleman , 1971) in which a rating of 1 represented a guess and a rating of 7 indicated complete confidence in their decisions. Intermediate values represented degrees of confidence between these two extremes. To provide the listeners with a perceptual frame of reference upon which to base their judgments, five pairs of readings were presented for practice purposes prior to the listeners' judgments of the 36 experimental pairs. All auditory stimuli were presented binaurally in a sound-treated room using an Ampex model602 tape recorder and matched Sharpe model HA-IOA headphones. Results
Correct height and weight descriminations Tables I and II contain the mean, standard deviation, and range values for the number of correct listener height and weight discriminations for the 36 pairs of speakers on the male and female master tapes. The tables indicate the following: (1) For both height and weight T~ble I Mean, standard deviati011, and range values for number of correct height discriminations for the 36 pairs on the female and male master tapes
Female speakers -Male listeners Female listeners Male speakers Male lis.t eners Female listeners
Mean
s.d.
Range
22·60 22·85
3·59 4·26
17 - 28 13 - 30
22·60 20 ·80
3·25 3·78
16- 27 11-26
Table II Mean, standard deviation, and range values for number of correct weight discriminations for the 36 pairs on the female and male master tapes
Fem::tle speakers Male listeners Female listeners Male speakers Male listeners Female listeners
Mean
s.d.
Range
23·70 24·10
2·70 2·69
17 - 30 18-28
22 ·55 22·95
2 ·06 2·52
17-27 19-28
judgments , listeners exhibited greater accuracy for female than male speakers; however, the differences in number of correct judgments between the two speaker sexes were only 1·02 for height judgments and 1·15 for weight judgments. (2) For height discriminations, male listeners were more accurate in their judgments of male speakers, while female listeners were more accurate in judging female speakers; however , the differences in number of
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correct discriminations were only 0·25 for female speakers and 1.80 for male speakers. (3) For weight discriminations, female listeners were only slightly more accurate than male listeners in their judgments of both male and female speakers, ex hibiting a difference of 0-40 correct decisions . (4) Male listeners were equally as accurate in their height judgments of male and female speakers , while female listeners exhibited a difference of 2·05 correct discriminations between their judgments of the two speaker sexes. (5) For weight discriminations , both male and female liste ne rs exhibited a difference of 1· i 5 correct decisions between their judgments of male and female speakers. (6) Across all sex differences, listeners were found to be more accurate in their weight than height judgments ; however , the mean difference between the two tasks was on ly I ·I I correct discriminations. (7) Across all sex differences , listeners exhibited more variability in discrimination accuracy for height (mean variability = 13 ·50 correct) than for weight (mean variability = 10·50 correct) judgments. (8) For both height and weight judgme nts , female and male listeners ' accuracy for male and female speakers was better t han that expected by chance guessing (i.e. better than 50%) . Infe rential statistical analyses, consisting of sign tests, Wilco xo n matched-pairs signedranks tests , and Mann-Whitney U tests (Siegel , 1956), were perfo rmed to determine if the observed differences were statistically significant or chance occurrences. Results indicated the following: (1) The number of listeners' correct height discriminations was significantly different from chance guessing for both male (z = 4-43 , P < 0·01) and female (z = 5·10, P < O·Ol) speakers. (2) The number of listeners ' correct weight discriminations were significantly different from chance guessing for both male (z = 6·01 , P < 0 ·01) and female (z = 6·25, P < 0·01) speakers . (3) No significant differences were found in listener discriminations between male and female speakers for both height (z = 1 ·25 , P >0· 10) and weight (z = 1·25 , P >O·l 0) judgments . (4) There were no significant differences in height judgments between male and female listeners on the male ( U = 143 ·50, P > 0·05) and female ( U = 189 ·5 0 , P > 0·05) tapes. (5) For weight discriminations , there' were no significant differences between male and female listeners on the male (U = 115 ·50 , P >0·03) and female (U = 177 ·00 , P>0·05) tapes.
Confidence ratings Tables 3 and 4 contain the mean , standard deviation , and range values for the listene rs' confidence ratings of their height and weight discriminations for the 36 pairs on th e female and male master tapes. The tables indicate the following: (I) For both height and weight Table III Mean, standard deviation, and range values for listeners' confidence ratings of height discriminations for the 36 pairs on the female and male rriaster tapes
- - --.,--- -- - - -Mean ____ ~------ -~-~12_~-~--- ·-··
judgments, listeners exhibited greater confidence for their discriminations of male than female speakers; however , the differences between the two speaker sexes were only 0·10 for height and 0·08 for weight judgments. (2) Male listeners were more confident than female listeners in their height jud gments of both male and female spea kers ; howeve r, the difference in confidence ratings was only 0-43 for both spea ker sexes. (3) For weight discri mination s, female listeners were more confident in their judgments of female speakers, whjle male listeners showed greater confidence in their judgments of male spea ke rs: however.
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Table IV Mean, standard deviation, and range values for listeners' confidence ratings of weight discriminations for the 36 pairs on the female and male master tapes
Mean
s.d.
Range
Female speakers Male listeners Female list eners
4-43 4 ·56
0·94 0·76
2·28 - 6·78 2·88 - 5·92
Male speakers Male listeners Femal e listen ers
4 ·66 4-49
1· 16 0·99
2·17 - 6 ·08 2·31 - 6·00
the differences between the listener sexes were slight: 0 ·13 for female speakers and 0 ·17 for male speakers. (4) For height judgments , both male and female listeners exhibited a difference in confidence of only 0·10 between the two speaker sexes. (5) For weight discriminations , female listeners exhibited a confidence difference between male and female speakers of 0 ·07, while male listene rs showed a difference of 0·23 in their confidence judgments of both speaker sexes. (6) Across all sex differences , listeners were found to be more confident in their weight than height judgments ; however , the mean difference between the two tasks was only 0 ·26 . (7) Across all sex differences, listeners exhibited more variability in discrimination confidence for height (mean variability= 4 ·33) than for weight (mean variability = 3 ·78) judgments . To determine if the observed differences were statistically significant or chance occurrences , inferential statistical analyses, consisting of Wilcoxon matched-pairs signed-ranks tests and Mann-Whitney U tests (Siegel , 1956) , were performed on the confidence data . Results indicated the following: (1) There were no significant differences in listener confi dence between male and female speakers for both weight (z = 0·72, P >0·20) and height (z = 0 ·9 5 , P >O ·17) judgme nts. (2) No significant differences in height judgments were found between male and female listeners on the male (U = 135·00, P >0 ·05) and female (U = 134 ·00 , P >0 ·05) tapes. (3) For weight judgments , there were no significant differences between male and female listeners on the male (U = 174·50, P >0 ·05) and female (U= 191 ·00 , P > 0·05) tapes . Discussion The results of this investigation corroborate those obtained by Lass & Davis (1976) and Lass et al. (1978) : listeners are capable of making accurate judgments concerning speakers' heights and weights when presented with only their ··recorded speech samples. For both speaker and listener sex groups in this study, discrimination accuracy was always greater than chance-guessing levels . Therefore , apparently there are adequate perceptual cues in the voice which reflect , to some extent, the physical features of height and weight of speakers. The present findings have also shown that the sex of the speaker and listener does not appear to be an important variable in speaker height and weight discrimination judgments. This finding is in agreement with that obtained by Lass et al. (1978), but not with that of the Lass & Davis (1976) study in which listeners were more accurate in their identification of the heights of male speakers and the weights of female speakers. However , it should be noted that because of differences among these three studies in employed experimental tasks , as well as differences between the two identification tasks employed in the Lass et al. (1978) and Lass & Davis (1976) experiments, these differences are not surprising . The listeners in the Lass & Davis study were given four choices of heights and weights from which to choose their answers, while those in the Lass et al. study made direct estimations of the heights and weights of speakers, with no multiple choices available to them . Moreover, the subjects in the present study were asked to make comparative judgments on pairs of speakers rather than absolute identifications of height and weight. Perhaps these task differences account, at
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least partially, for the differences in findings regarding the importance of the speaker and listener sex . Listener accuracy in the present study for both height and weight judgments was found to be better than that exhibited by the listeners in the Lass & Davis (1976) study·. The difference for height judgments was 5 ·50 correct decisions, and for weight judgments it was 3·80 correct decisions. This finding is not surprising since the task of height and weight discrimination appears to be less difficult than a height and weight identification task. In the discrimination task, the listeners need to differentiate between the heights and weights of two speakers presented in pairs rather than attempting to determine the approximate heights and weights of speakers individually, as in an identification task. However, the differences between these two kinds of tasks may not be as great as anticipated since, on the basis of the probability of chance-guessing accuracy, the differences between the two procedures are slight. The probability of being correct by chance in the Lass and Davis experiment was found to be between 045 and 0·65 for identifications of the heights and weights of male and female speakers , while the probability of guessing correctly for the discrimination task in the present study was 0·50. The results of the present investigation as well as those of the earlier studies by Lass & Davis (1976) and Lass et al. (1978) are encouraging enough to warrant continued investigation of speaker height and weight identifications . Future research will need to analyze the vocal characteristics of speakers in an attempt to isolate and define the in1portant acoustic cues in the voice which reflect speakers' heights and weights. This information , along with additional evidence which has been gathered on other speaker characteristics, including age (Ptacek & Sander , 1966 ; Shipp & Hollien , 1969 ; Ryan & Burk, 1972; Burket a!., 1975; Hartman & Danhauer, 1975), sex (Schwartz, 1968; Schwartz & Rine, 1968; lngemann, 1968; Coleman, 1971, 1973a, b; Abrams, 1973; Lass et al., 1976; Lass et a!., 1979, race (Stroud, 1956; Hibler, 1960; Dickens & Sawyer, 1962; Larson & Larson, 1966; Bryden, 1968; Alvarenga, 1971; Abrams, 1973; Lass et al., 1979), socioeconomic status (Harms, 1961 , 1963), personality (Stagner , 1936 ; Eisenberg & · Zalowitz , 1938; Markel , Eisler & Reese, 1967), specific identity (McGehee, 1937 ; Pollack , Pickett & Sumby, 1954 ; Compton, 1963; Voiers , 1964 ; Clarke, Becker & Nixon, 1966; Bricker & Pruzansky, 1966 ; Holmgren , 1967 ; Stevens eta!., 1968; Clarke & Becker , 1969; Cole men, 1973c), and facial and bodily features (Lass & Harvey, 1976), may prove very useful in a number of future theoretical and applied areas of investigation , including criminal investigation and law enforcement. For example , if the specific vocal cues responsible for speaker height and weight identification were empirically determined, listeners could be trained to concentrate on such cues in an attempt to improve their accuracy. Furthermore, if this information were combined with .evidence available on other physical characteristics of speakers, perhaps profiles could be generated on perpetrators of crimes committed by recorded spoken messages, such as bomb threats and ransom messages . The recordings would be judged perceptually by a group of trained listeners who would identify certain features of the speakers, including their age, race, sex , height , and weight. From these profiles law enforcement officers would have a basis for at least initiating their investigations int o such crimes. For instance, knowing that the perpet rator of a crime is 30 - 39 years of age, male , Caucasian, over 6' tall, and over 200 lb may lead to the further investigation of certain suspects, especially among previously known offenders committing similar crimes. Of course, one of the assumptions made in the above discussion is that the important acoustic cues used in the perceptual identification of speaker characteristics of height and weight can be determined . Another assumption is that listeners, by concentrating on such cues , can improve their accuracy of such judgments. A third assumption pertain s to the reliability of listeners' judgments. And , finally, it is assumed that listener accuracy is not affected by speakers ' attempts to disguise their true vocal characteristics. It remains for
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future research to clarify these assumptions in an attempt to determine the usefulness of perceptual "judgments of height, weight, and other speaker characteristics in law enforcement activities.
References Abrams. A. S. (1973). Minimal auditory cues for distinguishing black from white talkers. Unpublished Doctoral dissertation, City University of New York. Alvarenga, J. A. ( 1971 ). An investigation of the ability of listeners to differentiate race on the basis of tape recorded evidence. Unpublished Master's thesis, Herbert H. Lehman College, City University of New York. Bricker, P. D. & Pruzansky , S. (1966). Effects of stimulus content and duration on talker identification. Journal o(the Acoustical Society of America 40, 1441 - 1449. Bryden, J. D·. ( 1968). An acousti c and social dialect analy sis of perceptual variables in listener identification and rating of Negro speakers. Unpublished Doctoral dissertation, University of Virginia. Burk, K. W. , Hoyer, E. A. , f'ey , M. & Charlip, W. S. ( 1975). Perceptual and acoustic correlates of aging in the female voice. Paper presented at the Annual Com•ention of the American Speech and Hearing Association , Washington, D. C. Clarke, F. R., Becker, R. W. & Nixon, J. C. (1966). Characteristics that Determine Speaker Recognition. Report ESD-TR-66-636. Hanscom Field: Electron ics Systems Division, Air Force Systems Command. ('Iarke, F. R. Becker, R. W. & Nixon, 1. C. (1966). Characteristics that determine Speaker Recognition. Report ESD -TR-66-636. Hascom Field: Electronics Systems Division, Air Force Systems Command. Coleman, R. 0. ( 1971 ). Male and female voice quality and its relationship to vowel formant frequencies. Journal of Speech and Hearing Research. 14,565 - 577. Coleman, R. 0. ( 197 3a) . A comparison of the contributions of two vocal characteristics to the perception of maleness and femaleness in the voice. Paper presented at the Annual Convention of the American
Speech and Hearing Association, Detroit, Michigan. Coleman , R. 0. ( 197 3b). A comparison of the contributions of two vocal characteristics to the perception of maleness and femaleness in the voice. Quarterly Progress Speech Research. Stockholm, Sweden: Speech Transmission Laboratory , Royal Institute of Technology. Coleman, R. 0. ( 197 3c). Speaker identification in the absence of inter-subject differences in glottal source characteristics . Journal of the Acoustical Society of A me rica 53, 1741 - 1743. Compton, A. J. ( 1963). Effects of filterin.[: and vocal duration upon the identification of speakers, aurally. Journal of the Acoustical Society of America 35, 1748 - 1752. Dickens, M. & Sawyer, G. M. ( 1962). An experimental comparison of vocal quality among mixed groups of Whites and Negroes. Southern Speech Journal 18, 178 - 185 . Eisenberg, P., & Zalowitz, f' . ( 1938). Judging expressive movements. Ill. Judgments of dominancefeeling from phonograph records of voice. Journal of Applied PsycholoKY 22, 620 - 631. Fairbanks, G. (1960). Voice and Articulation Drillbook. New York; Harper & Row. Guilford, J.P. (1954). Psychometric Methods. New York: McGraw-Hill. Harms, L. S. ( 1961 ). Listener judgments of status cues in speech. Quarterly Journal of Speech 47, 164 - 168. Harms, L. S. ( 1963). Listener comphrension of speakers of three status groups. Language and Speech. 4,109 - 112. Hartman, D. f.., & Danhauer, J. L. ( 197 5 ). Perceptual features of aging male speech. Paper presented at the 90th Meeting of the Acoustical Society of A meriL·a, San Francisco, California. Hibler, M. B. ( 1960). A comparative study of speech patterns of selected Negro and White kindergarten chi ldren. Unpublished Doctoral dissertation, University of Southern California. Holmgren, G. L. ( 1967). Physical nnd psychological correlates of speaker recognition. Journal of Speech and Hearing Research I 0, 5.7 - 66. ln)'emann. F. (1968). Id entification of the speaker's sex from voiceless fricatives. Journal of the Acoustical Society of A me rica 44, 1142 - 1144. larson. V. S. & Larson , C. H. ( 1966). Reactions to pronunciation. In McDavid, R. 1., and Austin, W. M., Communimtion Barriers to the Culturally Depril'ed. Washington. D.C.: U.S. Office of Education. Cooperative Research Project Number 2107. Lass. N. J .. Bevcrl y , A. S. , Nicosia , D. K. & Simpson, L.A. (1978). An investigation of speaker height ~md weight ident ification by means of direct estimations. Journal of Phonetics 6, 69 - 76. Lass. N. .1. & Davis. M. (1976). i\n investigation of speaker height and weight identification. Journal of !he Acoustical Society ofAmaica 60,700- 703.
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Lass , N.J. & Harvey. L.A. (1976). An in vestigation of speaker photograph id e ntification. Journal of th e
Acoustical Society of America 59, 1232- 1236. Lass, N. J. , Hughes, K. R., Bowyer, M. D. , Waters, L. T. & Bourne, V. T . (1976). Speaker sex identifi ca tio n fro m voi ced , whispered and fil tered isolated vowe ls. Journal of the Acoustical Society
of America 59, 615 - 678. Lass, N.J. , T ecca, J. E., Man cuso, R. A. & Black, W. I. (1979). T he effect of phonetic co mplex ity on speaker race and sex identifi ca tion. Journal of Ph onetics 7, I 05 - 118. Markel , N. , Eisler, R. M. & Reese, H. W. (1967). Judging perso nality from dialect. Journal of Verba l
Learning and Verbal Behavior 6, 33 - 35. McGe hee , 1:. ( 193 7) . T he reliabili ty of th e ide ntification of t he hu ma n voice. Journal of General
Psy chology 17,249 - 27 1. Pollack, 1., Picket, J . M., & Sumby, W. H. (1954). On the id entification of speake rs by voice. Journal
of th e Acoustical Society of A me rica 26, 403 - 406. Ptacek , P. H. & Sander, E. K. (1966). Age recog nitio n fro m voice. Journal of Speech and Hearing
R esearch 9, 273 - 277. Ross, R. T. ( 1934 ). Optimal o rd e rs for th e presen tation of pairs in t he me thod o f paired co mpariso n.
Journal of Hducarional Psycho logy 25 , 375 . Rya n , W. J., & Burk , K. W. ( 1972). Pred ic tors of age in t he male voice. Pape r presented at the 84 th
Meeting of the Acoustical Society of A me rica, Miami Beach Florida. Schwartz, M. F. ( 1968). Id entifi cat ion of speaker se:x from iso lated , voiceless fr icatives. Journal of th e
Acoustical Society of America 43, 11 78 - 11 79. Schwart z., M. F. & Rin e, H. E. (1968) . Ide ntificat io n of spea ker sex from iso lated, whi spered vowels. Journal of th e Acoustical Society of America 44, 1736 - 1737 . Shipp, F. T. & Ho llie n , H. ( 1969). Pe rceptio n of t he ag ing male vo ice. Journal of Speech and Hearing
R esearch 12,703 - 710. Siege l, S. ( 1956). Nonparametric Statistics for th e Beha vioral Sciences. New York: McGraw-Hill. Stag ner, R. ( 1936). Judg ment s of vo ice and personality. Journal of Educational Psychology 27, 272 - 277. Steve ns, K. N., Williams, C. E., Carbonell , J . R. & Wood s. B. (1 968). Speake r a uthent icat ion an d id e ntifi cat io n : a co m par iso n of spectrographic a nd a udi tory presentations of spee ch material. Journal of the Acoustical Society of A me rica 44, 1596 - 1607. Stroud , R. V. ( 1956). A study of the relatio n between soc ial distan ce and speech differences of White and Neg ro high school stud ents of Day ton, Ohio. Unpublished Mast e r's th esis, Bowling Green State University. Voiers. W. D. ( 1964) . Perce ptual bases of spea ker id e ntit y. Journal o( th e A cousrical Society of A me rica
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An investigation of speaker height and Weight Discriminations by means of paired comparison judgments Norman J. Lass* , George W. Brong, Sharon A. Cicco lelia, Sandra C. Walters and Ellen L. Maxwell Speech and Hearing Sciences Labora to ry, West Virginia Un iversity , Mu•;;.:rntown, West Virginia 26506 , U.S.A. R eceiPed 4th September 1978
Abstract :
T he p urpo se of this inve stig atio n was to determine if listeners were capab le o f making accurate comparative judgments of speakers' heights and we ights when presented with pairs of recorded speech samp les. A stan d a rd prose passage was reco rd ed by 18 speake rs, nine fe m ales and nin e mal es. Two mast e r tapes were constructed , o ne for eac h speaker sex. A paired co mp ar iso n procedure was employed in the preparation of th e tapes, so that eac h tape co ntain ed a total of 36 pairs o f read in gs [ n(n -1 )/2 1. The readings in eac h pair co nsisted of the third se nt ence from the speak e rs' re cordings of the standard prose passage. The ma ster ta pes were pl ayed to a gro up o f 40 judges, 20 females and 20 ma les , fo r height a nd weight discrimination judgments. All liste ne rs parti cipat ed in tw o sessions, one for h e ight a nd one for weight judgments. They were asked to jud ge which m ember of eac h pair was heavi er or t a ll er as well as the co n fid ence of eac h d ecisio n o n a seve n-point confidence rating scale. Resu lts o f their judgme nt s indi cate that li steners are capa ble of mak in g accurate discr imin ations of speake rs' height s and weights a t bett e r than chance-guessing leve ls. Moreove r, th e sex of th e speake r a nd li st ene r did not signi fica ntly affect he ight and weight judgme nts . Im p li cations of th ese find ings and sugg estion s for future re searc h are discussed .
ln~roduction
Contemporary resear ch o n speaker identification has also included the study of speaker heig ht a nd we ight ide ntificatio ns. In addi tion to speaker age (Ptacek & Sander , 1966;Shipp & Ho lli en , 1969 ; Ryan & Burk , 1972; Burk et a!. ; 1975; Hartman & Danhauer, 1975) , sex (Schwartz, 1968; Schwartz & Rin e , 1968 ; I nge ma nn , 1968 ; Co leman , 197 1 , 1973a, b; Abrams , 1973; Lass eta!. , 1976; Lass et a!. , 1979), race (Stroud , 1956 ; Hibler , 1960 ; Di c ken s & Sawye r , 1962; Larson & Larso n , 1966; Bryden , 1968 ; Alvarenga, 1971 ; Abrams, 1973 ; Lass ct al. , 1979) , socioecono mi c status (Harms , 1961, 1963) , personalit y (Stagner , 1936: Eise n berg & Zalowitz, 1938 ; Markel , Eisler & Reese , 1967) , spe cific identity (McGehee , 193 7 ; Pollack , Pickett & Sumb y, 1954 ; Co mpton , 1963; Vo iers , 1964; Clarke , Becker & Nixo n . 1996 ; Bricker & Pruza nsky , 1966; Ho lmgren, 1967; Stevens et al. , 1968; Cia rkc & Bec ker , _1969: Co lem an , 1973c) , and fac ial a nd bodily featu res (Lass & Harvey,
* CorrL'SP
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1976) , listeners have also been found to be capable of speaker height and weight identifications with better than chance-guessing accuracy. In a study by !...ass & Davis (1976) , listeners were given a multiple-choice respon se task for their height and weight judgments. Four choices were provided for each speaker. For height judgments , the choices were : (a) under 5'0" ; (b) 5'0"-5'5"; (c) 5'6"-6'0" ; and (d) over 6'0". For weight judgments, the choices were (a) under 100 lb; (b) 100-150 lb; (c) 151-200 lb; and (d) over 200 lb. Results indicated that listeners were capable of accurately identifying the heights of male and female speakers and the weights of male speakers at better than chance levels. In a second study , Lass et al. ( 1978) attempted to determine if listeners were also capable of the more demanding task of making direct estimations of speakers' heights and weights from recorded speech samples, without the use of multiple-choice responses . It was found that listeners were capable of accurately identifying the approximate heights and weights of speakers at ·better than chance levels , and that th e sex of the speaker and listener did not significantly affect speaker height and weight judgments. The purpose of the present investigation was to determine if listeners were also capable of making accurate comparative judgments of height and weight when presented with pairs of recorded samples of speakers' voices. Method
Speakers A total of 18 speakers, nine females and nine males , participated in the study. All were students at West Virginia University with normal speech characteristics and no reported hearing difficulty. The heights of all speakers were obtained by usin g a tape measure attached to a wall ; the speakers' weights were obtained from a standard floor scale . The same tape meas•.ue and scale and identical measurement procedures were employed for height and weight determinations for all speakers in the study. The range of heights was 57- 75 in for females and 63- 80 in for males. The range of weights for females was 92-220 ib, and 115-200 lb for males. · Construction of master tapes The speakers' readings of the first paragraph of Fairbanks' (1960) The Rainbow Passage were recorded in a sound-treated room using an Ampex model 602 tape recorder and an Altec model 681 A condenser microphone . A total of two master tapes were constructed, one for female speakers and one for male speakers. A paired comparison proced ure (Guilford , 1954) was employed in the preparation of the tapes. Each tape contained 36 pairs of readings [n(n -- 1)/2], with each of the nine speakers ' readings appearing eight times on each tape. The readings employed in each pair consisted of the third sentence of the recorded passage, which was electronically extracted from the original recording . For both tapes , the o rder employed for presentation of the pairs of readings as well as the order for the memb ers of each pair was developed for paired comparison tasks by Ross (1934) to avoid time and space errors. A one-second pause was inserted between the two recordings in each pair , and a seven-second pause was inserted between each pair to allow sufficient time for listener judgments. In addition to the 36 pairs of readings , each tape included five pairs to be judged for practice purposes . Therefore , each tape contained a total of 41 pairs of readings . Both master tapes were constructed by means of electronic reproductions of the speakers ' original reco rdings. All reproductions were made using high-quality recording equipment in the Speech and Hearing Sciences Laboratory at West Virginia University . Experimental sessions A total of 40 judges, 20 females and 20 males , participated in th e st udy. All were students at West Virginia University and reported no hearing difficulty. The judges were unfamiliar
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with the speakers on the master tapes, as determined by their responses to a list of names of the speakers prior to their participation in the study. The judges participated in a total of two sessions, one for height judgments and one for weight judgments. In each session the listeners heard both the male and female tapes. The order of presentation of the height and weight discrimination tasks was randomized so that 20 subjects (10 females and 10 males) made height judgments in the first session and weight judgments in the second session , while 20 subjects (1 0 females and 10 males) made weight judgments in the first session and height judgments in the second session. In addition, the order of presentation of the male and female master tapes in each session was randomized. In all experimental sessions , the listeners heard pairs of speakers' recorded readings and were asked to judge which member of each pair was heavier or taller. In addition, they were also asked to indicate the confidence of each of their judgments by means of a seven-point confidence rating scale (Coleman , 1971) in which a rating of 1 represented a guess and a rating of 7 indicated complete confidence in their decisions. Intermediate values represented degrees of confidence between these two extremes. To provide the listeners with a perceptual frame of reference upon which to base their judgments, five pairs of readings were presented for practice purposes prior to the listeners' judgments of the 36 experimental pairs. All auditory stimuli were presented binaurally in a sound-treated room using an Ampex model602 tape recorder and matched Sharpe model HA-IOA headphones. Results
Correct height and weight descriminations Tables I and II contain the mean, standard deviation, and range values for the number of correct listener height and weight discriminations for the 36 pairs of speakers on the male and female master tapes. The tables indicate the following: (1) For both height and weight T~ble I Mean, standard deviati011, and range values for number of correct height discriminations for the 36 pairs on the female and male master tapes
Female speakers -Male listeners Female listeners Male speakers Male lis.t eners Female listeners
Mean
s.d.
Range
22·60 22·85
3·59 4·26
17 - 28 13 - 30
22·60 20 ·80
3·25 3·78
16- 27 11-26
Table II Mean, standard deviation, and range values for number of correct weight discriminations for the 36 pairs on the female and male master tapes
Fem::tle speakers Male listeners Female listeners Male speakers Male listeners Female listeners
Mean
s.d.
Range
23·70 24·10
2·70 2·69
17 - 30 18-28
22 ·55 22·95
2 ·06 2·52
17-27 19-28
judgments , listeners exhibited greater accuracy for female than male speakers; however, the differences in number of correct judgments between the two speaker sexes were only 1·02 for height judgments and 1·15 for weight judgments. (2) For height discriminations, male listeners were more accurate in their judgments of male speakers, while female listeners were more accurate in judging female speakers; however , the differences in number of
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correct discriminations were only 0·25 for female speakers and 1.80 for male speakers. (3) For weight discriminations, female listeners were only slightly more accurate than male listeners in their judgments of both male and female speakers, ex hibiting a difference of 0-40 correct decisions . (4) Male listeners were equally as accurate in their height judgments of male and female speakers , while female listeners exhibited a difference of 2·05 correct discriminations between their judgments of the two speaker sexes. (5) For weight discriminations , both male and female liste ne rs exhibited a difference of 1· i 5 correct decisions between their judgments of male and female speakers. (6) Across all sex differences, listeners were found to be more accurate in their weight than height judgments ; however , the mean difference between the two tasks was on ly I ·I I correct discriminations. (7) Across all sex differences , listeners exhibited more variability in discrimination accuracy for height (mean variability = 13 ·50 correct) than for weight (mean variability = 10·50 correct) judgments. (8) For both height and weight judgme nts , female and male listeners ' accuracy for male and female speakers was better t han that expected by chance guessing (i.e. better than 50%) . Infe rential statistical analyses, consisting of sign tests, Wilco xo n matched-pairs signedranks tests , and Mann-Whitney U tests (Siegel , 1956), were perfo rmed to determine if the observed differences were statistically significant or chance occurrences. Results indicated the following: (1) The number of listeners' correct height discriminations was significantly different from chance guessing for both male (z = 4-43 , P < 0·01) and female (z = 5·10, P < O·Ol) speakers. (2) The number of listeners ' correct weight discriminations were significantly different from chance guessing for both male (z = 6·01 , P < 0 ·01) and female (z = 6·25, P < 0·01) speakers . (3) No significant differences were found in listener discriminations between male and female speakers for both height (z = 1 ·25 , P >0· 10) and weight (z = 1·25 , P >O·l 0) judgments . (4) There were no significant differences in height judgments between male and female listeners on the male ( U = 143 ·50, P > 0·05) and female ( U = 189 ·5 0 , P > 0·05) tapes. (5) For weight discriminations , there' were no significant differences between male and female listeners on the male (U = 115 ·50 , P >0·03) and female (U = 177 ·00 , P>0·05) tapes.
Confidence ratings Tables 3 and 4 contain the mean , standard deviation , and range values for the listene rs' confidence ratings of their height and weight discriminations for the 36 pairs on th e female and male master tapes. The tables indicate the following: (I) For both height and weight Table III Mean, standard deviation, and range values for listeners' confidence ratings of height discriminations for the 36 pairs on the female and male rriaster tapes
- - --.,--- -- - - -Mean ____ ~------ -~-~12_~-~--- ·-··
judgments, listeners exhibited greater confidence for their discriminations of male than female speakers; however , the differences between the two speaker sexes were only 0·10 for height and 0·08 for weight judgments. (2) Male listeners were more confident than female listeners in their height jud gments of both male and female spea kers ; howeve r, the difference in confidence ratings was only 0-43 for both spea ker sexes. (3) For weight discri mination s, female listeners were more confident in their judgments of female speakers, whjle male listeners showed greater confidence in their judgments of male spea ke rs: however.
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Table IV Mean, standard deviation, and range values for listeners' confidence ratings of weight discriminations for the 36 pairs on the female and male master tapes
Mean
s.d.
Range
Female speakers Male listeners Female list eners
4-43 4 ·56
0·94 0·76
2·28 - 6·78 2·88 - 5·92
Male speakers Male listeners Femal e listen ers
4 ·66 4-49
1· 16 0·99
2·17 - 6 ·08 2·31 - 6·00
the differences between the listener sexes were slight: 0 ·13 for female speakers and 0 ·17 for male speakers. (4) For height judgments , both male and female listeners exhibited a difference in confidence of only 0·10 between the two speaker sexes. (5) For weight discriminations , female listeners exhibited a confidence difference between male and female speakers of 0 ·07, while male listene rs showed a difference of 0·23 in their confidence judgments of both speaker sexes. (6) Across all sex differences , listeners were found to be more confident in their weight than height judgments ; however , the mean difference between the two tasks was only 0 ·26 . (7) Across all sex differences, listeners exhibited more variability in discrimination confidence for height (mean variability= 4 ·33) than for weight (mean variability = 3 ·78) judgments . To determine if the observed differences were statistically significant or chance occurrences , inferential statistical analyses, consisting of Wilcoxon matched-pairs signed-ranks tests and Mann-Whitney U tests (Siegel , 1956) , were performed on the confidence data . Results indicated the following: (1) There were no significant differences in listener confi dence between male and female speakers for both weight (z = 0·72, P >0·20) and height (z = 0 ·9 5 , P >O ·17) judgme nts. (2) No significant differences in height judgments were found between male and female listeners on the male (U = 135·00, P >0 ·05) and female (U = 134 ·00 , P >0 ·05) tapes. (3) For weight judgments , there were no significant differences between male and female listeners on the male (U = 174·50, P >0 ·05) and female (U= 191 ·00 , P > 0·05) tapes . Discussion The results of this investigation corroborate those obtained by Lass & Davis (1976) and Lass et al. (1978) : listeners are capable of making accurate judgments concerning speakers' heights and weights when presented with only their ··recorded speech samples. For both speaker and listener sex groups in this study, discrimination accuracy was always greater than chance-guessing levels . Therefore , apparently there are adequate perceptual cues in the voice which reflect , to some extent, the physical features of height and weight of speakers. The present findings have also shown that the sex of the speaker and listener does not appear to be an important variable in speaker height and weight discrimination judgments. This finding is in agreement with that obtained by Lass et al. (1978), but not with that of the Lass & Davis (1976) study in which listeners were more accurate in their identification of the heights of male speakers and the weights of female speakers. However , it should be noted that because of differences among these three studies in employed experimental tasks , as well as differences between the two identification tasks employed in the Lass et al. (1978) and Lass & Davis (1976) experiments, these differences are not surprising . The listeners in the Lass & Davis study were given four choices of heights and weights from which to choose their answers, while those in the Lass et al. study made direct estimations of the heights and weights of speakers, with no multiple choices available to them . Moreover, the subjects in the present study were asked to make comparative judgments on pairs of speakers rather than absolute identifications of height and weight. Perhaps these task differences account, at
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N.J. Lass eta!.
least partially, for the differences in findings regarding the importance of the speaker and listener sex . Listener accuracy in the present study for both height and weight judgments was found to be better than that exhibited by the listeners in the Lass & Davis (1976) study·. The difference for height judgments was 5 ·50 correct decisions, and for weight judgments it was 3·80 correct decisions. This finding is not surprising since the task of height and weight discrimination appears to be less difficult than a height and weight identification task. In the discrimination task, the listeners need to differentiate between the heights and weights of two speakers presented in pairs rather than attempting to determine the approximate heights and weights of speakers individually, as in an identification task. However, the differences between these two kinds of tasks may not be as great as anticipated since, on the basis of the probability of chance-guessing accuracy, the differences between the two procedures are slight. The probability of being correct by chance in the Lass and Davis experiment was found to be between 045 and 0·65 for identifications of the heights and weights of male and female speakers , while the probability of guessing correctly for the discrimination task in the present study was 0·50. The results of the present investigation as well as those of the earlier studies by Lass & Davis (1976) and Lass et al. (1978) are encouraging enough to warrant continued investigation of speaker height and weight identifications . Future research will need to analyze the vocal characteristics of speakers in an attempt to isolate and define the in1portant acoustic cues in the voice which reflect speakers' heights and weights. This information , along with additional evidence which has been gathered on other speaker characteristics, including age (Ptacek & Sander , 1966 ; Shipp & Hollien , 1969 ; Ryan & Burk, 1972; Burket a!., 1975; Hartman & Danhauer, 1975), sex (Schwartz, 1968; Schwartz & Rine, 1968; lngemann, 1968; Coleman, 1971, 1973a, b; Abrams, 1973; Lass et al., 1976; Lass et a!., 1979, race (Stroud, 1956; Hibler, 1960; Dickens & Sawyer, 1962; Larson & Larson, 1966; Bryden, 1968; Alvarenga, 1971; Abrams, 1973; Lass et al., 1979), socioeconomic status (Harms, 1961 , 1963), personality (Stagner , 1936 ; Eisenberg & · Zalowitz , 1938; Markel , Eisler & Reese, 1967), specific identity (McGehee, 1937 ; Pollack , Pickett & Sumby, 1954 ; Compton, 1963; Voiers , 1964 ; Clarke, Becker & Nixon, 1966; Bricker & Pruzansky, 1966 ; Holmgren , 1967 ; Stevens eta!., 1968; Clarke & Becker , 1969; Cole men, 1973c), and facial and bodily features (Lass & Harvey, 1976), may prove very useful in a number of future theoretical and applied areas of investigation , including criminal investigation and law enforcement. For example , if the specific vocal cues responsible for speaker height and weight identification were empirically determined, listeners could be trained to concentrate on such cues in an attempt to improve their accuracy. Furthermore, if this information were combined with .evidence available on other physical characteristics of speakers, perhaps profiles could be generated on perpetrators of crimes committed by recorded spoken messages, such as bomb threats and ransom messages . The recordings would be judged perceptually by a group of trained listeners who would identify certain features of the speakers, including their age, race, sex , height , and weight. From these profiles law enforcement officers would have a basis for at least initiating their investigations int o such crimes. For instance, knowing that the perpet rator of a crime is 30 - 39 years of age, male , Caucasian, over 6' tall, and over 200 lb may lead to the further investigation of certain suspects, especially among previously known offenders committing similar crimes. Of course, one of the assumptions made in the above discussion is that the important acoustic cues used in the perceptual identification of speaker characteristics of height and weight can be determined . Another assumption is that listeners, by concentrating on such cues , can improve their accuracy of such judgments. A third assumption pertain s to the reliability of listeners' judgments. And , finally, it is assumed that listener accuracy is not affected by speakers ' attempts to disguise their true vocal characteristics. It remains for
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future research to clarify these assumptions in an attempt to determine the usefulness of perceptual "judgments of height, weight, and other speaker characteristics in law enforcement activities.
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