42
A MULTIDIMENSIONAL SCALING ANALYSIS OF PHONEMIC RESPONSES FROM HARD OF HEARING AND DEAF SUBJECTS OF THREE LANGUAGES*
JEFFREY L. DANHAUER** and SADANAND Ohio
SINGH
University
Twenty logatoms (CVCV) involving five vowels and 20 consonants were presented subjects, 18 hard of hearing and 18 deaf. Of the 18 subjects, six were speakers of English (American), six Serbo-Croatian (Yugoslavian), and six French (French), The logatoms were analysed for both initial and medial consonants. The responses were recorded on magnetic tape and transcribed phonetically by three judges. The data were analysed by IND-SCAL and reported in unique dimension. Twelve groups of similarity matrices mainly yielded two- and three- dimensional solutions. The interpretations of these dimensions were mainly voicing and sibilant. Additional features retrieved in some cases included nasality, fricative, and others. Recovery of similar space for three language groups, two deviancy groups, and two positions reveal "universal" dimensionality and features of the consonants. to 36
INTRODUCTION
The purposes of the present study are: (1) to find perceptual features of the phonemes of the hard of hearing and deaf subjects of three languages independently: English, Serbo-Croatian, and French; (2) to determine the weightings of the perceptual features of each subject; (3) to compare the features and their weightings with the individual’s audiogram; and (4) to describe the perceptual features and their relative weightings by the hard of hearing and deaf subjects of the three languages in the framework of a &dquo;universal&dquo; phonetic theory. In the past, attempts have been made to apply a priari phonetic features to predict the responscs of persons with sensorineural hearing impairments. For example, Siegenthaler (1954) found that voicing was discriminated better than place, which in turn, was perceived better than manner when hearing impaired listeners were tested for consonant discrimination at or near threshold. Pickett (1972) studied the responses of subjects with profound sensorineural impairments to rhyme tests. He concluded that (1) phonetic features used by deaf listeners to perceive and discriminate speech sounds are the same as those used by normal listeners; (2) sensorineural listeners can process low frequency patterns such as voicing and nasal murmurs better than middle and high frequency patterns such as bursts after voiceless stops and fricatives; *
The authors wish to thank Dr. Dean Christopher and Mr. Dan Kelly for assisting in the phonetic transcription. A Portion ofthis work (second author) was supported by a grant from the Ohio University research foundation. **Now at Bowling Green State University.
43 the low frequency patterns hold true for a wide range of degrees and types of sensorineural impairments; and (4) initial consonants are perceived better than final consonants by hearing impaired listeners. Bilger, Wang, and Jesteadt (1972) studied twenty-two hearing impaired subjects and constructed confusion matrices for four sets of nonsense syllables in &dquo;ABX Triads&dquo; with sixteen consonants and three vowels of CV and VC nature. The stimuli were presented at about 40 db. above the subjects’ thresholds. The Chomsky and Halle feature system was utilized in the interpretation of this data. An iterative procedure showed that subjects utilized features differently. Thus, earlier studies involving acoustically impaired individuals have been, primarily, a process of imposing the phonetic and/or linguistic features of normal hearing listeners onto the speech products of the hearing impaired. The present study was designed to deviate substantially from the above process by employing a multi-dimensional analysis, Individual Differences Scaling (IND-SCAL), to the perceptual/productive confusions of deaf and hard of hearing subjects in order to retrieve the perceptual features utilized by these subjects.
(3)
SUBJECT
SELECTION
The subjects for the study were thirty-six hearing impaired children with the mean age of 8.77 years, who had been previously trained via low frequency amplification. Three groups of twelve subjects, of whom six were severely hard of hearing, and six of whom were profoundly deaf, were selected from the Verbo-tonal centres in three different countries, namely, Knoxville, Tennessee, U.S.A.; Zagreb, Yugoslavia; and Paris, France. The criteria for selection were: (1) that all subjects be previously trained with low frequency amplification and that they could respond to the task of the experiment; and (2) that all subjects be either severely hard of hearing or profoundly deaf. Audiometric evaluations using ISO standards were administered on each subject and compared to previous audiograms for reliability of the pure tone thresholds. Subjects were placed in one of two groups depending upon the pure tone average of the better ear. A subject with hearing better than 90 db. yet poorer than 60 db. was considered severely hard of hearing. A subject with hearing poorer than 90 db. was considered profoundly deaf (Danhauer, 1972).
STIMULI 20 speech-like logatoms, repeated CV combinations, for example: constructed from the 20 consonants and five vowels common to /baba/. They the three languages. Each of the five vowels was randomly paired with four of the twenty consonants and presented to the subjects via low frequency hearing aids and
The stimuli
were
were
44 of the subjects’ native tongues. The stimuli and the subjects’ responses recorded on magnetic tape. Three different hearing aids of similar frequency characteristics and of low frequency emphasis were employed. The aids emphasized the frequencies below 1000 c.p.s. and extended to about 250 c.p.s. or lower. Each subject was presented with a different randomization of the twenty stimuli for each hearing aid until he had been tested with all three aids. Each subject was told that he was to listen to the stimuli and to repeat what he heard. A few logatoms were presented as examples and when the subject understood that he was to repeat what he heard the test began. The tape recordings of the speakers’ stimuli and the subjects’ responses were phonetically transcribed by three judges experienced in phonetic transcription. After the transcriptions were performed the data was separated into twelve groups (three languages x two contexts, initial and medial, x two hearing impairments, hard of
by speakers were
hearing
and deaf). This study was only concerned with finding the initial and medial consonantal features of the above groups and the vowels were not further treated. Thirty-six symmetric matrices were constructed from the tallies of the consonantal errors and used as input for the IND-SCAL analysis. The IND-SCAL analysis procedure was used to determine the individual differences among the subjects in each group and to present information which would be useful in determining the actual consonantal perceptual features utilized by each of the hearing impaired subjects in their responses to the test stimuli. IND-SCAL analysis provided group stimulus space for each of the twelve groups of subjects and the individual subject space within each group in two, three, four, five, and six dimensional spaces. The analysis in two through six dimensional space is typically considered exploratory in order to discover the unique dimensionality for each group of subjects. The dimensionality for a group of subjects was considered final when the criteria of interpretability of the data and the uniqueness of solution were met. A solution was considered unique in the event that the stimuli converged to identical points although the IND-SCAL iterative procedures started from two different random generating numbers. In order to ensure maximum convergence, the criteria for stopping iterations was zero. Usually, the convergence of points was unique in only one of the five spaces in which the data were analysed. In the event that uniqueness occurred at more spaces for a given group, the criterion of interpretability was considered the decisive factor (McGregor, 1973). It is generally believed that consonant perception is multi-dimensional (Singh, Woods, and Becker, 1972; Singh and Becker, 1972; Graham and House, 1971; Singh, Woods, and Tishman, 1972; and Singh and Singh, 1972). It is also believed that different groups of subjects with different perceptual strategies, for example, language backgrounds or hearing deficiencies, perceive identical sets of sounds in different dimensionalities (Singh and Woods, 1972; and McGregor, 1973).
45
,
Fig.
1
Stimulus and subject spaces of initial
consonants
of American hard of
hearing
RESULTS Prior to presenting the results it should be noted that of the two through five dimensional solutions only the unique dimensional spaces are being reported each time. In cases where no additional interpretability was gained by going to a higher dimensionality, even if the higher solution was unique, no higher solutions are reported. Tables 1 and 2 show the interpreted feature labels assigned to the co-ordinate system of the unique dimension and the percentage of accounted variability contributed by that dimension for each group of subjects. Figs. 1 through 17 show the plottings of the stimulus spaces and the subject spaces (in the upper right comer) for the unique solutions of each group of subjects. The figure at the upper right corner, although corresponding to the stimulus spaces, utilizes an independent co-ordinate system. Fig. 1 shows Dl and D2 of the 2-D unique solution for the American hard of hearing subjects for initial consonants (AHI). The interpreted labels for the features are: Dl (sibilant with the misplacement of /f/; fricative with the misplacement of /h/; and velar place), and D2 (voicing). The word &dquo;misplacement&dquo; means that a consonant is not placed such that it can be classified correctly as a member of the interpreted feature. Of the 21’% total accounted variance reported, the contribution of each
46 dimension was: Dl (12%) and D2 (9~%). It may be noted here that the low accountability of the variance was partly because of the selection of the 2-D space. In a 6-D space for example, on the average, a group accounted for about 50% of the total variance. Fig. 1 also shows the corresponding subject space for the two dimensions. Although no subject shows excessively poor or high weights on either dimension, subjects 1, 2, and 4 have poorer weightings for both Dl and D2. Figs. 2 and 3 show Dl, D2, and D3 of a 3-D solution for the American hard of hearing subjects for medial consonants (AHM). The labels for the features and the contribution to the 27% total accounted variance of each dimension are: Dl (voicing, 10%), D2 (not interpreted-NI, 9~%), and D3 (nasality, 8~%). Also shown in Figs. 2 and 3 are the corresponding subject spaces for the three dimensions. Subject 1 has poor weightings on Dl and subject 6 on D3. Dl and D2 of the 2-D solution for the group of American deaf subjects for initial consonants (ADI) are shown in Fig. 4. The labels for the features and the contribution to the 1T% total accounted variance of each dimension are: Dl (voicing with the misplacement of /d3/ and sonorant, 9%), and D2 (liquid, 8’%). Also seen in Fig. 4 are the corresponding subject spaces for the two dimensions. Although no subject shows extremely poor weightings for either dimension, subject 5 deviates on both Dl and D2. Fig. 5 shows D1 and D2 in a 2-D solution for the American deaf subjects for medial consonants (ADM). The labels and the contribution to the 19% total accounted variance for each dimension are: Dl (N1, 8%), and D2 (stop with the misplacement of /b/, 11’%). Fig. 5 also shows the corresponding subject spaces for Dl and D2. Subject 5 has poor weightings for D2, yet high for Dl. In Figs. 6 and 7 D1, D2, D3, and D4 are shown for a 4-D solution for the Yugoslavian hard of hearing subjects for initial consonants (YHI). The labels and the contribution to the total 3 6’% accounted variance of each dimension are: Dl1 (sibilant with the misplacement of /g/, 10%), D2 (nasality and voicing, 10%), D3 (nasality, 8%), and D4 (voiced stop and fricative labials, 8’%). The corresponding
subject spaces for each dimension are also seen in Figs. 6 and 7. Subject 1 is poor on D2, yet his weights are highest of the group for Dl. Subjects 1 and 5 are poor on D3, while subject 3 is poorest cn D4. Fig. 8 shows Dl and D2 in a 2-D solution for Yugoslavian hard of hearing subjects for medial consonants (YHM). The labels and the contribution to the 21’% total variance of each dimension are: Dl (voicing with /h/ misplaced and nasality, 10%) and D2 (sibilant with /t~/ misplaced, 11’%). This figure also shows the subject spaces for Dl and D2. While subjects 3 and 6 are the &dquo; best &dquo; subjects on both dimensions, subject 5 is poor on Dl and subject 4 is poor on D2. Fig. 9 shows D1 and D2 in a 2-D solution for the Yugoslavian deaf subjects for initial consonants (YDI). The labels for each dimension and its contribution to the total 21~% variance are: Dl (sibilant with /f/ misplaced, 10%) and D2 (stop/continuant tendency, 11’%). Fig 9 also shows the subject spaces for Dl and D2 on which all
subjects’ weightings
were
fairly equal.
47
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A MULTIDIMENSIONAL SCALING ANALYSIS OF PHONEMIC RESPONSES FROM HARD OF HEARING AND DEAF SUBJECTS OF THREE LANGUAGES*
JEFFREY L. DANHAUER** and SADANAND Ohio
SINGH
University
Twenty logatoms (CVCV) involving five vowels and 20 consonants were presented subjects, 18 hard of hearing and 18 deaf. Of the 18 subjects, six were speakers of English (American), six Serbo-Croatian (Yugoslavian), and six French (French), The logatoms were analysed for both initial and medial consonants. The responses were recorded on magnetic tape and transcribed phonetically by three judges. The data were analysed by IND-SCAL and reported in unique dimension. Twelve groups of similarity matrices mainly yielded two- and three- dimensional solutions. The interpretations of these dimensions were mainly voicing and sibilant. Additional features retrieved in some cases included nasality, fricative, and others. Recovery of similar space for three language groups, two deviancy groups, and two positions reveal "universal" dimensionality and features of the consonants. to 36
INTRODUCTION
The purposes of the present study are: (1) to find perceptual features of the phonemes of the hard of hearing and deaf subjects of three languages independently: English, Serbo-Croatian, and French; (2) to determine the weightings of the perceptual features of each subject; (3) to compare the features and their weightings with the individual’s audiogram; and (4) to describe the perceptual features and their relative weightings by the hard of hearing and deaf subjects of the three languages in the framework of a &dquo;universal&dquo; phonetic theory. In the past, attempts have been made to apply a priari phonetic features to predict the responscs of persons with sensorineural hearing impairments. For example, Siegenthaler (1954) found that voicing was discriminated better than place, which in turn, was perceived better than manner when hearing impaired listeners were tested for consonant discrimination at or near threshold. Pickett (1972) studied the responses of subjects with profound sensorineural impairments to rhyme tests. He concluded that (1) phonetic features used by deaf listeners to perceive and discriminate speech sounds are the same as those used by normal listeners; (2) sensorineural listeners can process low frequency patterns such as voicing and nasal murmurs better than middle and high frequency patterns such as bursts after voiceless stops and fricatives; *
The authors wish to thank Dr. Dean Christopher and Mr. Dan Kelly for assisting in the phonetic transcription. A Portion ofthis work (second author) was supported by a grant from the Ohio University research foundation. **Now at Bowling Green State University.
43 the low frequency patterns hold true for a wide range of degrees and types of sensorineural impairments; and (4) initial consonants are perceived better than final consonants by hearing impaired listeners. Bilger, Wang, and Jesteadt (1972) studied twenty-two hearing impaired subjects and constructed confusion matrices for four sets of nonsense syllables in &dquo;ABX Triads&dquo; with sixteen consonants and three vowels of CV and VC nature. The stimuli were presented at about 40 db. above the subjects’ thresholds. The Chomsky and Halle feature system was utilized in the interpretation of this data. An iterative procedure showed that subjects utilized features differently. Thus, earlier studies involving acoustically impaired individuals have been, primarily, a process of imposing the phonetic and/or linguistic features of normal hearing listeners onto the speech products of the hearing impaired. The present study was designed to deviate substantially from the above process by employing a multi-dimensional analysis, Individual Differences Scaling (IND-SCAL), to the perceptual/productive confusions of deaf and hard of hearing subjects in order to retrieve the perceptual features utilized by these subjects.
(3)
SUBJECT
SELECTION
The subjects for the study were thirty-six hearing impaired children with the mean age of 8.77 years, who had been previously trained via low frequency amplification. Three groups of twelve subjects, of whom six were severely hard of hearing, and six of whom were profoundly deaf, were selected from the Verbo-tonal centres in three different countries, namely, Knoxville, Tennessee, U.S.A.; Zagreb, Yugoslavia; and Paris, France. The criteria for selection were: (1) that all subjects be previously trained with low frequency amplification and that they could respond to the task of the experiment; and (2) that all subjects be either severely hard of hearing or profoundly deaf. Audiometric evaluations using ISO standards were administered on each subject and compared to previous audiograms for reliability of the pure tone thresholds. Subjects were placed in one of two groups depending upon the pure tone average of the better ear. A subject with hearing better than 90 db. yet poorer than 60 db. was considered severely hard of hearing. A subject with hearing poorer than 90 db. was considered profoundly deaf (Danhauer, 1972).
STIMULI 20 speech-like logatoms, repeated CV combinations, for example: constructed from the 20 consonants and five vowels common to /baba/. They the three languages. Each of the five vowels was randomly paired with four of the twenty consonants and presented to the subjects via low frequency hearing aids and
The stimuli
were
were
44 of the subjects’ native tongues. The stimuli and the subjects’ responses recorded on magnetic tape. Three different hearing aids of similar frequency characteristics and of low frequency emphasis were employed. The aids emphasized the frequencies below 1000 c.p.s. and extended to about 250 c.p.s. or lower. Each subject was presented with a different randomization of the twenty stimuli for each hearing aid until he had been tested with all three aids. Each subject was told that he was to listen to the stimuli and to repeat what he heard. A few logatoms were presented as examples and when the subject understood that he was to repeat what he heard the test began. The tape recordings of the speakers’ stimuli and the subjects’ responses were phonetically transcribed by three judges experienced in phonetic transcription. After the transcriptions were performed the data was separated into twelve groups (three languages x two contexts, initial and medial, x two hearing impairments, hard of
by speakers were
hearing
and deaf). This study was only concerned with finding the initial and medial consonantal features of the above groups and the vowels were not further treated. Thirty-six symmetric matrices were constructed from the tallies of the consonantal errors and used as input for the IND-SCAL analysis. The IND-SCAL analysis procedure was used to determine the individual differences among the subjects in each group and to present information which would be useful in determining the actual consonantal perceptual features utilized by each of the hearing impaired subjects in their responses to the test stimuli. IND-SCAL analysis provided group stimulus space for each of the twelve groups of subjects and the individual subject space within each group in two, three, four, five, and six dimensional spaces. The analysis in two through six dimensional space is typically considered exploratory in order to discover the unique dimensionality for each group of subjects. The dimensionality for a group of subjects was considered final when the criteria of interpretability of the data and the uniqueness of solution were met. A solution was considered unique in the event that the stimuli converged to identical points although the IND-SCAL iterative procedures started from two different random generating numbers. In order to ensure maximum convergence, the criteria for stopping iterations was zero. Usually, the convergence of points was unique in only one of the five spaces in which the data were analysed. In the event that uniqueness occurred at more spaces for a given group, the criterion of interpretability was considered the decisive factor (McGregor, 1973). It is generally believed that consonant perception is multi-dimensional (Singh, Woods, and Becker, 1972; Singh and Becker, 1972; Graham and House, 1971; Singh, Woods, and Tishman, 1972; and Singh and Singh, 1972). It is also believed that different groups of subjects with different perceptual strategies, for example, language backgrounds or hearing deficiencies, perceive identical sets of sounds in different dimensionalities (Singh and Woods, 1972; and McGregor, 1973).
45
,
Fig.
1
Stimulus and subject spaces of initial
consonants
of American hard of
hearing
RESULTS Prior to presenting the results it should be noted that of the two through five dimensional solutions only the unique dimensional spaces are being reported each time. In cases where no additional interpretability was gained by going to a higher dimensionality, even if the higher solution was unique, no higher solutions are reported. Tables 1 and 2 show the interpreted feature labels assigned to the co-ordinate system of the unique dimension and the percentage of accounted variability contributed by that dimension for each group of subjects. Figs. 1 through 17 show the plottings of the stimulus spaces and the subject spaces (in the upper right comer) for the unique solutions of each group of subjects. The figure at the upper right corner, although corresponding to the stimulus spaces, utilizes an independent co-ordinate system. Fig. 1 shows Dl and D2 of the 2-D unique solution for the American hard of hearing subjects for initial consonants (AHI). The interpreted labels for the features are: Dl (sibilant with the misplacement of /f/; fricative with the misplacement of /h/; and velar place), and D2 (voicing). The word &dquo;misplacement&dquo; means that a consonant is not placed such that it can be classified correctly as a member of the interpreted feature. Of the 21’% total accounted variance reported, the contribution of each
46 dimension was: Dl (12%) and D2 (9~%). It may be noted here that the low accountability of the variance was partly because of the selection of the 2-D space. In a 6-D space for example, on the average, a group accounted for about 50% of the total variance. Fig. 1 also shows the corresponding subject space for the two dimensions. Although no subject shows excessively poor or high weights on either dimension, subjects 1, 2, and 4 have poorer weightings for both Dl and D2. Figs. 2 and 3 show Dl, D2, and D3 of a 3-D solution for the American hard of hearing subjects for medial consonants (AHM). The labels for the features and the contribution to the 27% total accounted variance of each dimension are: Dl (voicing, 10%), D2 (not interpreted-NI, 9~%), and D3 (nasality, 8~%). Also shown in Figs. 2 and 3 are the corresponding subject spaces for the three dimensions. Subject 1 has poor weightings on Dl and subject 6 on D3. Dl and D2 of the 2-D solution for the group of American deaf subjects for initial consonants (ADI) are shown in Fig. 4. The labels for the features and the contribution to the 1T% total accounted variance of each dimension are: Dl (voicing with the misplacement of /d3/ and sonorant, 9%), and D2 (liquid, 8’%). Also seen in Fig. 4 are the corresponding subject spaces for the two dimensions. Although no subject shows extremely poor weightings for either dimension, subject 5 deviates on both Dl and D2. Fig. 5 shows D1 and D2 in a 2-D solution for the American deaf subjects for medial consonants (ADM). The labels and the contribution to the 19% total accounted variance for each dimension are: Dl (N1, 8%), and D2 (stop with the misplacement of /b/, 11’%). Fig. 5 also shows the corresponding subject spaces for Dl and D2. Subject 5 has poor weightings for D2, yet high for Dl. In Figs. 6 and 7 D1, D2, D3, and D4 are shown for a 4-D solution for the Yugoslavian hard of hearing subjects for initial consonants (YHI). The labels and the contribution to the total 3 6’% accounted variance of each dimension are: Dl1 (sibilant with the misplacement of /g/, 10%), D2 (nasality and voicing, 10%), D3 (nasality, 8%), and D4 (voiced stop and fricative labials, 8’%). The corresponding
subject spaces for each dimension are also seen in Figs. 6 and 7. Subject 1 is poor on D2, yet his weights are highest of the group for Dl. Subjects 1 and 5 are poor on D3, while subject 3 is poorest cn D4. Fig. 8 shows Dl and D2 in a 2-D solution for Yugoslavian hard of hearing subjects for medial consonants (YHM). The labels and the contribution to the 21’% total variance of each dimension are: Dl (voicing with /h/ misplaced and nasality, 10%) and D2 (sibilant with /t~/ misplaced, 11’%). This figure also shows the subject spaces for Dl and D2. While subjects 3 and 6 are the &dquo; best &dquo; subjects on both dimensions, subject 5 is poor on Dl and subject 4 is poor on D2. Fig. 9 shows D1 and D2 in a 2-D solution for the Yugoslavian deaf subjects for initial consonants (YDI). The labels for each dimension and its contribution to the total 21~% variance are: Dl (sibilant with /f/ misplaced, 10%) and D2 (stop/continuant tendency, 11’%). Fig 9 also shows the subject spaces for Dl and D2 on which all
subjects’ weightings
were
fairly equal.
47
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