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Factors influencing the measurement of oral and nasal sound pressure level
Journal of Phonetics (1982) 10,245-250
Factors influencing the measurement of oral and nasal sound pressure level Wayne M. Clarke and W. J. Hardcastle* School of English and Linguistics, Macquarie University, North Ryde, N.S. W., Australia 2113 Received 3rd August 1981
Abstract:
An experiment was carried out to detect the various variables that appear to influence the measurement of oral/nasal sound pressure ratios in CV and VC environments. Significant factors were found to include the sex of the subject, the vowel height and the position of the vowel relative to the consonant.
Introduction In previous research Clarke & Mackiewicz-Krassowska (1977) found an increase in oral/ nasal sound pressure ratio on high front vowels when produced in /vowel nasal/ frames. The results of that investigation suggested that the position of the tongue appeared to be a variable in this measurement and that vela-pharyngeal valving was influenced by the preceding vowel position. In some initial research in this area Clarke (1975) found a number of variables which also influenced the measurement of oral/nasal sound pressure ratio, the most important of which appeared to be the sex of the speaker. Clarke found that in the longterm measurement of oral/nasal sound pressure ratio females tended to have a higher oral/ nasal sound pressure ratio than males. In this present research an attempt was made to repeat some of this earlier work and to try to detect the various variables that appear to influence measurement of oral/nasal sound pressure ratios. The specific aims of this research were to determine whether or not female speakers produce greater oral/nasal sound pressure ratios on individual vowels than do male speakers. A second aim was to examine the oral/nasal sound pressure ratios in both nasal and non-nasal utterances and thus examine the coarticualtion characteristics of nasal consonants. Procedure
Subjects The subject group used in the investigation consisted of seven male and 13 female adult speakers. All of the subjects were born in Australia and they were all judged to have normal speech.
*On leave from the Department of Linguistic Science, Reading University, Reading, England. 0095-4470/82/030245 + 06 $03.00/0
© 1982 Academic Press Inc. (London) Ltd .
246
W. M. Clarke and W. J. Hardcastle Experimental procedure
The recording instrumentation and the computer analysis used were the same as those described by Clarke (1975) and Clarke & Mackiewicz-Krassowska (1977). The recording procedure involved the use of an oral/nasal separator (Hyde, 1968) into which each subject uttered a series of 16 test items. The test items consisted of monosyllable words which were produced three times by each subject, and in the latter part of the analysis the average value for each of the items was obtained. The words consisted of a high and low vowel preceded by and following both a nasal and oral stop consonant. The production of these utterances were recorded on a twin track tape recorder and an oral/nasal sound pressure ratio was obtained for each subject producing the various items. Results
Mean values were calculated for the oral/nasal sound pressure ratio for each vowel in each phonetic frame . A summary of the mean results is shown in Figs 1-5. The data was then analysed using a series of analysis of variance procedures for unequal population samples as described by Winer (1971). The results of the statistical comparisons are shown in the following tables. Table I is a summary of the analysis of variance used to compare the oral/ nasal sound pressure ratios of the vowels for male and female speakers and nasal and nonnasal syllable productions. The fmding of a significant F ratio for Factor B indicated that there was a significantly higher oral/nasal sound pressure ratio for vowels associated with nasal consonants than with those associated with non-nasal consonants. In Table II an analysis of variance procedure was used to compare the oral/nasal sound pressure ratio on high vowels and low vowels and to make these comparisons for male and female speakers. These results indicated a significant difference between the vowels with the high vowels producing a greater oral/nasal sound pressure ratio. Examination of the significant AB interation indicated that the female speakers produced a higher oral/nasal sound pressure ratio for high vowels than did the male speakers. 60
Nasal 50,--
.g E' 40 r-
~·
•
~
""'
NonNasal nasal
"'
~
a_ "0
c:
Male
30 r-
"
0
"' "'c:
42 ·2
17· 6
Female 50·3
18-4
0
0
'0
201-
0
·-------------------·Non-nasal
10 r-
o~----J~-------------------~~--~ Male
Figure 1
Female
Mean values of oral/nasal sound pressure ratios for vowels associated with nasal and non-nasal consonants.
Oral and nasal sound pressure level 60
247
•
- - - - - H i g h vowel
501-
•
-~
2 401~
"
~
a.
"0
.------ --
___
....
--
-·
- - Low vowel
....
301-
c
"
0
c
'
High
201-
0
0
Male
Low
52·3 32·1
Female 57·8 42·8
101-
0
Figure 2
I
I
Male
Female
Mean values of oral/nasal sound pressure ratios for vowels associated with high and low articulatory placement.
60 Preceding
50 r-
-------------· ----·
• 0
e· 401~
"
--·--- ---
Following
~
a. "0
c
"
301-
0
-c
0
c-
c
::, 2010
Male
0
46·9 37·5
Female 52·2 45-4
10
0
Figure 3
I Male
I Female
Mean values of oral/nasal sound pressure ratios for vowels preceding and following the nasal consonant.
The data used in Table III compared the oral/nasal sound pressure ratio for vowels preceding and following the nasal consonants and this resulted in the fmding of a significant F ratio. Examination of the means indicated that the vowels preceding the consonant produced a greater ratio than did the vowels following the consonant. In Table IV an analysis
W. M. Clarke and W. J. Hardcastle
248
60.---------------------------------,
lml 501-
~~
.·- --------
~-----
0
~ ~
401-
~
/n/
~
0.
"0
;
301-
0
"' 0 "'c:0 :;
o
/m/ Mole
20 t-
/n/
41·3 43 · 1
Female 49·6 50·9
101-
OL-----~------------------~----~
Mole
Female
Mean values of oral/nasal sound pressure ratios for vowels associated with /m/
Figure 4
and /n/. 60
50 High
..,
.0
\'0 40
Mole
~
Low
18 ·0 18-42
Female 20·4 15·6
~ ~
0. "0
c:
"'~
30-
0
"'c:0
'
0
-· ---·
High vowel
20-
1-==-- ------
0
----
Law vowel
101-
0
Figure 5
I Mole
I
Female
Mean values of oral/nasal sound pressure ratios for high and low vowels produced in a non-nasal environment .
of variance was used to determine differences between oral/nasal sound pressure ratio for vowels associated with /m/ and /n/. These fmdings did not indicate a significant difference between the two sets of data. The data used in Table V excluded all syllables which included a nasal consonant and the
Oral and nasal sound pressure level
249
Table I Summary of analysis of variance used to determine differences between vowels for males and femals and nasal and non-nasal syllables Source of variation
df
Between subjects Factor A (male/female) Subj . w . groups Within subjects Factor B (nasal/non-nasal) AB B X subj. w . groups
19 1 18 40 1 1 38
1
MS
127.4 73 .3 7626.7 391.3 20.78
F
2.45 349.50 1 18.83 1
Significant at 0.01 level of probability.
Table II Summary of analysis of variance used to determine differences between vowels for males and females and high and low articulatory placement Source of variation
df
Between subjects Factor A (male/female) Subj. w. groups Within subjects Factor B (high v low) AB B X subj . w. groups
19 1 18 40 1 1 38
1
MS
597 .05 155 .98 2818.1 61.50 7. 15
F
3.82 394.23 1 8.60 1
Significant at 0.01 level of probability.
Table Ill Summary of analysis of variance used to determine differences between vowels for males and females and preceding and following nasal consonants Source of variation
df
Between subjects Factor A (male/female) Subj. w. groups Within subjects Factor B ( -C, C- ) AB B X subj. w. groups
19 1 18 40 1 1 38
1
MS
F
597 .05 155 .98
3.82
839 .0 0.4 75.8
11.06 1 0.01
Significant at 0.01 level of probability.
Table IV Summary of analysis of variance used to determine differences between vowels for males and females and /m/ and /n/ consonants Source of variation
df
Between subjects Factor A (male/female) Subj. w. groups Within subjects Factor B (/m/, fnf) AB B X subj . w. groups
19 1 18 40 1 1 38
MS
F
597 .05 155.98
3.82
20.47 0.81 5.2
3.94 0.15
250
W M. Clarke and W J. Hardcastle Table V Summary of analysis of variance used to determine differences between high and low vowels in a non-nasal articulatory environment
Source of variation
df
MS
F
Between subjects Factor A (male/female) Subj. w. groups Within subjects Factor B (high/low vowels) AB B x subj. w. groups
19 1 18
6.82 82.00
0.08
40 1 1 38
51.05 56 .33 66.32
0.76 0.85
analysis of variance was used to determine the differences bewteen oral/nasal sound pressure ratio for male and female speakers in a high and low vowel placement. These fmdings did not indicate a significant difference between the sexes or the vowel placement. Discussion The use of oral/nasal sound pressure ratio as an objective measure of nasality does not appear to be any more reliable than any other method of nasality assessment, and the tremendous variations in the results of various researchers is well known. The results of this particular research, however, indicate that any individual result must be considered against the sex of the subject , the vowel height and the position of the vowel relative to the consonant. It is interesting to compare these results with studies of the physiology of the nasopharyngeal mechanism. X-ray studies like that of Bzoch (1968) indicated that there is a compensatory movement of the naso-pharyngeal sphicter during the production of high vowels in non-nasal environments. In the present study this coarticulation of the tongue and soft palate only occurs, however, on vowels preceding the nasal consonant and is considerably altered in female speakers . The suggestion that female speakers have different velopharyngeal valving because of anatomical differences cannot be supported, and thus we must conclude that this particular oral/nasal resonance is probably socially determined. References Bzoch, K. R. (1968). Variations in velopharyngeal valving: the factor of vowel changes. Cleft Palate Journal, 5, 211-218. Clarke, W. M. (1975) . The measurement of the oral and nasal sound pressure levels of speech. Journal of Phonetics, 3, 257-62 . Clarke, W. M. & Mackiewicz-Krassowska, H. (1977). Variation in the oral and nasal sound pressure levels of vowels in changing phonetic contexts. Journal of Phonetics, 5 , 195-203. Hyde, S. (1968). Nose trumpet: apparatus for separating the oral and nasal outputs in speech. Nature, London, 219,763-765 . Winer, B. (1971), Statistical Principles in Experimental Design. New York: McGraw Hill.
Factors influencing the measurement of oral and nasal sound pressure level Wayne M. Clarke and W. J. Hardcastle* School of English and Linguistics, Macquarie University, North Ryde, N.S. W., Australia 2113 Received 3rd August 1981
Abstract:
An experiment was carried out to detect the various variables that appear to influence the measurement of oral/nasal sound pressure ratios in CV and VC environments. Significant factors were found to include the sex of the subject, the vowel height and the position of the vowel relative to the consonant.
Introduction In previous research Clarke & Mackiewicz-Krassowska (1977) found an increase in oral/ nasal sound pressure ratio on high front vowels when produced in /vowel nasal/ frames. The results of that investigation suggested that the position of the tongue appeared to be a variable in this measurement and that vela-pharyngeal valving was influenced by the preceding vowel position. In some initial research in this area Clarke (1975) found a number of variables which also influenced the measurement of oral/nasal sound pressure ratio, the most important of which appeared to be the sex of the speaker. Clarke found that in the longterm measurement of oral/nasal sound pressure ratio females tended to have a higher oral/ nasal sound pressure ratio than males. In this present research an attempt was made to repeat some of this earlier work and to try to detect the various variables that appear to influence measurement of oral/nasal sound pressure ratios. The specific aims of this research were to determine whether or not female speakers produce greater oral/nasal sound pressure ratios on individual vowels than do male speakers. A second aim was to examine the oral/nasal sound pressure ratios in both nasal and non-nasal utterances and thus examine the coarticualtion characteristics of nasal consonants. Procedure
Subjects The subject group used in the investigation consisted of seven male and 13 female adult speakers. All of the subjects were born in Australia and they were all judged to have normal speech.
*On leave from the Department of Linguistic Science, Reading University, Reading, England. 0095-4470/82/030245 + 06 $03.00/0
© 1982 Academic Press Inc. (London) Ltd .
246
W. M. Clarke and W. J. Hardcastle Experimental procedure
The recording instrumentation and the computer analysis used were the same as those described by Clarke (1975) and Clarke & Mackiewicz-Krassowska (1977). The recording procedure involved the use of an oral/nasal separator (Hyde, 1968) into which each subject uttered a series of 16 test items. The test items consisted of monosyllable words which were produced three times by each subject, and in the latter part of the analysis the average value for each of the items was obtained. The words consisted of a high and low vowel preceded by and following both a nasal and oral stop consonant. The production of these utterances were recorded on a twin track tape recorder and an oral/nasal sound pressure ratio was obtained for each subject producing the various items. Results
Mean values were calculated for the oral/nasal sound pressure ratio for each vowel in each phonetic frame . A summary of the mean results is shown in Figs 1-5. The data was then analysed using a series of analysis of variance procedures for unequal population samples as described by Winer (1971). The results of the statistical comparisons are shown in the following tables. Table I is a summary of the analysis of variance used to compare the oral/ nasal sound pressure ratios of the vowels for male and female speakers and nasal and nonnasal syllable productions. The fmding of a significant F ratio for Factor B indicated that there was a significantly higher oral/nasal sound pressure ratio for vowels associated with nasal consonants than with those associated with non-nasal consonants. In Table II an analysis of variance procedure was used to compare the oral/nasal sound pressure ratio on high vowels and low vowels and to make these comparisons for male and female speakers. These results indicated a significant difference between the vowels with the high vowels producing a greater oral/nasal sound pressure ratio. Examination of the significant AB interation indicated that the female speakers produced a higher oral/nasal sound pressure ratio for high vowels than did the male speakers. 60
Nasal 50,--
.g E' 40 r-
~·
•
~
""'
NonNasal nasal
"'
~
a_ "0
c:
Male
30 r-
"
0
"' "'c:
42 ·2
17· 6
Female 50·3
18-4
0
0
'0
201-
0
·-------------------·Non-nasal
10 r-
o~----J~-------------------~~--~ Male
Figure 1
Female
Mean values of oral/nasal sound pressure ratios for vowels associated with nasal and non-nasal consonants.
Oral and nasal sound pressure level 60
247
•
- - - - - H i g h vowel
501-
•
-~
2 401~
"
~
a.
"0
.------ --
___
....
--
-·
- - Low vowel
....
301-
c
"
0
c
'
High
201-
0
0
Male
Low
52·3 32·1
Female 57·8 42·8
101-
0
Figure 2
I
I
Male
Female
Mean values of oral/nasal sound pressure ratios for vowels associated with high and low articulatory placement.
60 Preceding
50 r-
-------------· ----·
• 0
e· 401~
"
--·--- ---
Following
~
a. "0
c
"
301-
0
-c
0
c-
c
::, 2010
Male
0
46·9 37·5
Female 52·2 45-4
10
0
Figure 3
I Male
I Female
Mean values of oral/nasal sound pressure ratios for vowels preceding and following the nasal consonant.
The data used in Table III compared the oral/nasal sound pressure ratio for vowels preceding and following the nasal consonants and this resulted in the fmding of a significant F ratio. Examination of the means indicated that the vowels preceding the consonant produced a greater ratio than did the vowels following the consonant. In Table IV an analysis
W. M. Clarke and W. J. Hardcastle
248
60.---------------------------------,
lml 501-
~~
.·- --------
~-----
0
~ ~
401-
~
/n/
~
0.
"0
;
301-
0
"' 0 "'c:0 :;
o
/m/ Mole
20 t-
/n/
41·3 43 · 1
Female 49·6 50·9
101-
OL-----~------------------~----~
Mole
Female
Mean values of oral/nasal sound pressure ratios for vowels associated with /m/
Figure 4
and /n/. 60
50 High
..,
.0
\'0 40
Mole
~
Low
18 ·0 18-42
Female 20·4 15·6
~ ~
0. "0
c:
"'~
30-
0
"'c:0
'
0
-· ---·
High vowel
20-
1-==-- ------
0
----
Law vowel
101-
0
Figure 5
I Mole
I
Female
Mean values of oral/nasal sound pressure ratios for high and low vowels produced in a non-nasal environment .
of variance was used to determine differences between oral/nasal sound pressure ratio for vowels associated with /m/ and /n/. These fmdings did not indicate a significant difference between the two sets of data. The data used in Table V excluded all syllables which included a nasal consonant and the
Oral and nasal sound pressure level
249
Table I Summary of analysis of variance used to determine differences between vowels for males and femals and nasal and non-nasal syllables Source of variation
df
Between subjects Factor A (male/female) Subj . w . groups Within subjects Factor B (nasal/non-nasal) AB B X subj. w . groups
19 1 18 40 1 1 38
1
MS
127.4 73 .3 7626.7 391.3 20.78
F
2.45 349.50 1 18.83 1
Significant at 0.01 level of probability.
Table II Summary of analysis of variance used to determine differences between vowels for males and females and high and low articulatory placement Source of variation
df
Between subjects Factor A (male/female) Subj. w. groups Within subjects Factor B (high v low) AB B X subj . w. groups
19 1 18 40 1 1 38
1
MS
597 .05 155 .98 2818.1 61.50 7. 15
F
3.82 394.23 1 8.60 1
Significant at 0.01 level of probability.
Table Ill Summary of analysis of variance used to determine differences between vowels for males and females and preceding and following nasal consonants Source of variation
df
Between subjects Factor A (male/female) Subj. w. groups Within subjects Factor B ( -C, C- ) AB B X subj. w. groups
19 1 18 40 1 1 38
1
MS
F
597 .05 155 .98
3.82
839 .0 0.4 75.8
11.06 1 0.01
Significant at 0.01 level of probability.
Table IV Summary of analysis of variance used to determine differences between vowels for males and females and /m/ and /n/ consonants Source of variation
df
Between subjects Factor A (male/female) Subj. w. groups Within subjects Factor B (/m/, fnf) AB B X subj . w. groups
19 1 18 40 1 1 38
MS
F
597 .05 155.98
3.82
20.47 0.81 5.2
3.94 0.15
250
W M. Clarke and W J. Hardcastle Table V Summary of analysis of variance used to determine differences between high and low vowels in a non-nasal articulatory environment
Source of variation
df
MS
F
Between subjects Factor A (male/female) Subj. w. groups Within subjects Factor B (high/low vowels) AB B x subj. w. groups
19 1 18
6.82 82.00
0.08
40 1 1 38
51.05 56 .33 66.32
0.76 0.85
analysis of variance was used to determine the differences bewteen oral/nasal sound pressure ratio for male and female speakers in a high and low vowel placement. These fmdings did not indicate a significant difference between the sexes or the vowel placement. Discussion The use of oral/nasal sound pressure ratio as an objective measure of nasality does not appear to be any more reliable than any other method of nasality assessment, and the tremendous variations in the results of various researchers is well known. The results of this particular research, however, indicate that any individual result must be considered against the sex of the subject , the vowel height and the position of the vowel relative to the consonant. It is interesting to compare these results with studies of the physiology of the nasopharyngeal mechanism. X-ray studies like that of Bzoch (1968) indicated that there is a compensatory movement of the naso-pharyngeal sphicter during the production of high vowels in non-nasal environments. In the present study this coarticulation of the tongue and soft palate only occurs, however, on vowels preceding the nasal consonant and is considerably altered in female speakers . The suggestion that female speakers have different velopharyngeal valving because of anatomical differences cannot be supported, and thus we must conclude that this particular oral/nasal resonance is probably socially determined. References Bzoch, K. R. (1968). Variations in velopharyngeal valving: the factor of vowel changes. Cleft Palate Journal, 5, 211-218. Clarke, W. M. (1975) . The measurement of the oral and nasal sound pressure levels of speech. Journal of Phonetics, 3, 257-62 . Clarke, W. M. & Mackiewicz-Krassowska, H. (1977). Variation in the oral and nasal sound pressure levels of vowels in changing phonetic contexts. Journal of Phonetics, 5 , 195-203. Hyde, S. (1968). Nose trumpet: apparatus for separating the oral and nasal outputs in speech. Nature, London, 219,763-765 . Winer, B. (1971), Statistical Principles in Experimental Design. New York: McGraw Hill.