Original Paper Folia Phoniatr Logop 2015;67:42–48 DOI: 10.1159/000374110
Published online: May 19, 2015
Normative Data and Dialectical Effects on Nasalance in Flemish Adults Evelien D’haeseleer Kim Bettens Sarah De Mets Valerie De Moor Kristiane Van Lierde Department of Speech-, Language- and Hearing Sciences, Ghent University, Ghent, Belgium
Abstract Objective: The purpose of this study was to investigate the impact of dialect and gender and to obtain normative nasalance values for Flemish adults as measured with the Nasometer II. Subjects and Methods: One hundred and sixtyfour adult subjects from the five regions in Flanders corresponding to different dialects were included in the study. The group consisted of 71 adult men and 93 adult women with a mean age of 43 years and an age range between 20 and 82 years (SD 16). Nasalance scores of connected speech using an oral, an oronasal and a nasal text were measured with the Nasometer II model 6450. Results: The nasalance scores for the oral, oronasal and nasal texts are provided in this study. No significant differences were found across the five dialects and between men and women. Conclusion: This study provides new Flemish normative data as measured with the Nasometer II model 6450. The results of this study are very important for clinical purposes and for future Flemish studies collecting nasalance scores of subjects with different dialects. © 2015 S. Karger AG, Basel
© 2015 S. Karger AG, Basel 1021–7762/15/0671–0042$39.50/0 E-Mail [email protected] www.karger.com/fpl
Introduction
To measure the degree of nasality, perceptual as well as objective measurements are used and described in the literature [1]. Nasometry, originally developed by Fletcher and Bishop [2], is an effective diagnostic tool for detecting abnormalities in nasal resonance [1]. Different instruments for nasometry exist, of which the Nasometer is the one most frequently reported in the literature [3]. The system is easy to use because of its speed, noninvasiveness, objectivity and reliability [4, 5]. In the literature, normative data are available for variants of English, French, Cantonese, German, Finnish, Greek, Hungarian, Dutch, Spanish, Thai, Turkish, Swedish, Korean, Japanese and Flemish [3, 5–18]. Controversy exists about the influence of age, gender and dialect on nasalance scores as measured by the Nasometer [4, 6, 18– 31]. Regarding the impact of gender on nasalance, studies report higher nasalance scores in women [4, 6, 18–20, 22], due to anatomical and physiological differences between men and women [22] or differences in coarticulation [28]. Other studies have not reported any differences in nasalance scores between men and women [5, 7, 11, 17, 29–31]. Evelien D’haeseleer Department of Speech-, Language- and Hearing Sciences Ghent University, De Pintelaan 185, 2P1 BE–9000 Ghent (Belgium) E-Mail Evelien.Dhaeseleer @ ugent.be
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Key Words Nasalance · Dialect · Normative data · Flemish
Dialects can be discriminated by differences in sound system (pronunciation), vocabulary and grammar [32]. In English as well as in Flemish, dialect mainly has an influence on the production of vowels [32–34]. Vowels can be described in terms of high/low and front/back placement of the tongue in the oral cavity. Studies have shown that these differences in tongue placement can influence nasalance scores [35, 36]. Therefore, dialectical variations should be taken into account when studying nasal resonance. Differences in nasalance scores per dialect have been reported by Seaver et al. [22], Mayo et al. [30], Nichols [31] and Awan et al. [37]. Table 1 summarizes the literature regarding the impact of dialect and gender on nasalance scores in adults. Seaver et al. [22] investigated nasalance in four geographical regions of North America and found significantly higher nasalance scores for MidAtlantic English speakers. Between the other regions, very little difference was observed. Mayo et al. [30] studied nasalance in two races (African American/White American) speaking a Mid-Atlantic dialect of American English. They found significantly higher nasalance scores among the white speakers and hypothesized that these differences may be related to the cultural-linguistic background (rather than race). In a study by Nichols [31], differences in nasalance between Spanish speakers from two cities in Central Mexico were measured. Significant but small differences (3%) in mean nasalance scores were observed between the two cities. It is, however, unclear whether dialect can explain these differences. In a recent study, Awan et al. [37] investigated dialectical effects on nasalance in six different North American dialects. The effect sizes for dialect were moderate in strength and accounted for approximately 7–9% of the variation in nasalance. The highest nasalance rates were found in the Texas South dialectal region. They concluded that clinicians and researchers should be aware that dialectal speech patterns may influence nasalance values as well as the interpretation of normative expectations and typical versus disordered cutoff scores. Other authors have not found any impact of dialect on differences in nasalance by dialect [4, 7]. For Dutch and Flemish, no studies investigating the impact of dialect have been published. From the literature, it is clear that nasalance scores are language dependent [38]. Therefore, differences regarding age, gender and dialect should be investigated per language. Further variation is caused by the model of Nasometer used; studies have shown a variation of 1 or 2 points between the Nasometer model 6200, mostly used in previous studies, and the new models of the Nasometer
II (6400 and 6450) [39–41]. Although differences between the two models are not clinically relevant, Kummer [40] concluded that new norms should be used with the Nasometer II models 6400 and 6450. For Flemish (the language spoken in the northern part of Belgium), the impact of age on nasalance scores has already been investigated. Van Lierde et al. [18] investigated the differences in nasalance scores between Flemish children and adults and found that young adults had higher nasalance scores than children, particularly when the stimuli included nasal consonants. Between young and older adults, no differences in nasalance scores were found for Flemish [21]. The impact of gender on nasalance in the Flemish language was also investigated by Van Lierde et al. [18], and significantly higher scores were reported for women. However, none of the above-mentioned studies account for the possible influence of dialect on nasalance values in the Flemish language. From the literature it is clear that, in some cases, dialect can influence nasalance scores (table 1). For the future interpretation of nasalance data in clinical Flemish studies and for clinical practice, normative data on each dialect are necessary. The purpose of this study was to obtain normative nasalance values with the Nasometer II from a group of 164 normal adults. Secondly, the impact on nasalance of gender and dialect was investigated by comparing the nasalance scores between women and men and between speakers of the five dialects in Flanders (West Flanders, East Flanders, Antwerp, Flemish Brabant and Limburg). It was hypothesized that gender and the five Flemish dialects would have a significant impact on the nasalance scores.
Flemish Normative Data on Nasalance Scores
Folia Phoniatr Logop 2015;67:42–48 DOI: 10.1159/000374110
Subjects and Methods
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Participants Hundred and sixty-seven adult subjects from the five regions in Flanders corresponding to different dialects were included in the study. In Flanders, the five different dialectical regions with their corresponding specific dialects are West Flanders, East Flanders, Antwerp, Flemish Brabant and Limburg, as described by Timmermans [34]. The inclusion criteria for each dialect were very strict. The subjects included (1) had to be born and raised in the same region and (2) had to have self-reported speaking the specific dialect. Two speech-language therapists with 4 years of experience in detecting Flemish dialects perceptually judged their speech, and both confirmed the dialects in consensus. All subjects reported to have a normal hearing, a normal speech and language development, good general health and no history of speech therapy for a resonance disorder. Patients with nasal congestion or a cold at the moment of testing were excluded from the study (n = 3).
Table 1. Summary of the literature on the impact of dialect and gender on nasalance in adults Language
Gender M/F, n
Age, years
Hutchinson et al. [6], 1978
English
30/30
Seaver et al. [22], 1991
English in four 56/92 geographical regions of North America
Speech sample
Material
Effect of gender
Effect of dialect
50 – 80 Oral text; oronasal text; nasal text
Tonar II
Significantly higher scores in women
–
16 – 63 Oral text; oronasal text; nasal text
Nasometer 6200
Significantly higher scores in women for nasal sentences
Significantly higher nasalance scores were found in the MidAtlantic speakers for all three reading passages; very little difference was observed for three of the four regional speech patterns
Litzaw and English Dalston [29], 1992
15/15
>18
Oral text; oronasal text; nasal text
Nasometer 6200
No significant – differences between men and women
Kavanagh et al. [7], 1994
English, three Canadian dialects
16/36
18 – 33 Oral text; oronasal text; nasal text
Nasometer 6200
No differences between men and women
No differences in dialect
Mayo et al. [30], 1996
Mid-Atlantic dialect 40/40 of American English in two races (African American/White American)
>18 Oral text; (mean: nasal text 23)
Nasometer 6200
No differences between men and women
Significantly higher nasalance scores among the White American speakers; these differences may be related to the cultural-linguistic background (rather than race)
Rochet et al. [19], 1998
English and French
60/93
9 – 85
Oral text; oronasal text; nasal text
Nasometer 6200
Significantly higher scores in women for the oronasal text in English and the oronasal and nasal texts in French
–
Nichols [31], Spanish spoken in 1999 two cities in central Mexico
24/31
20 – 40 Oral text; oronasal text
Nasometer 6200
No differences in mean nasometric values between men and women; the minima of the oronasal text of women were significantly higher
Significant differences in mean nasalance scores for the oral text between the two cities (16 vs. 19%); it is, however, unclear whether dialect can explain these differences
Tachimura et al. [17], 2000
Japanese
50/50
19 – 35 Oral text
Nasometer 6200
No significant – differences between men and women
Van Lierde et al. [18], 2003
Flemish
28/30
19 – 27 Oral text; oronasal text; nasal text; vowels
Nasometer 6200
Significantly higher scores in women for the oronasal and nasal texts and the vowel /u/
Hirschberg et al. [5], 2006
Hungarian
75
5 – 25
Mishima et al. [4], 2008
Japanese in four regions: Chugoku, Kinki, Shikoku, other regions
31/37
Mean: Oral text; 23 vowels
Nasometer II 6400 Significantly higher scores in women for the oral text and the vowels
Okalidou et al. [11], 2011
Greek
40/40
18 – 34 Oral text; oronasal text; nasal text; SNAP test
Nasometer 6200-3
44
Nasometer 6400 Phonemes; syllables; oral sentence; oronasal sentence; nasal sentence
Folia Phoniatr Logop 2015;67:42–48 DOI: 10.1159/000374110
–
No significant – differences between men and women
No significant differences between the three regional dialects
No significant – differences between men and women
D’haeseleer/Bettens/De Mets/De Moor/ Van Lierde
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Study
Table 1 (continued) Study
Language
Gender M/F, n
Age, years
Abou-Elsaad Arabic et al. [20], 2012
62/70
18 – 54 SNAP test
Awan et al. [37], 2015
150/150 Mean: Oral text; 22 oronasal text; nasal text
English in six North American dialectal regions
Speech sample
Material
Effect of gender
Effect of dialect
Nasometer II 6400 Significantly higher scores in women
–
Nasometer II 6400 Significantly higher scores in women
Significant differences for dialect; the effect sizes for dialect were moderate in strength and accounted for approx. 7 – 9% of the variation in nasalance; the highest nasalance scores were found in the Texas South dialectal region
SNAP = Simplified Nasometric Assessment Procedures.
different Flemish dialectal regions Region
Men
Women
Total
West Flanders East Flanders Antwerp Flemish Brabant Limburg
13 25 6 15 12
17 25 16 17 18
30 50 22 32 30
The two speech-language therapists also perceptually judged the speech in consensus to detect abnormalities in resonance and articulation. Resonance was categorized as normal, hyponasal (mild, moderate or severe) or hypernasal (mild, moderate or severe), and articulation was rated as normal or abnormal (mild, moderate or severe). In all subjects, resonance and articulation were normal. The final group consisted of 164 subjects (167 minus 3 subjects with nasal congestion or a cold), 71 adult men and 93 adult women with a mean age of 43 years and an age range between 20 and 82 years (SD 16). Table 2 presents the number of men and women enrolled from the five different regions. Dialects Dialectal boundaries are established when there is a tendency for the majority of speakers in one region the use the same patterns of vowel production [37]. In Flanders, the five different dialectal regions are West Flanders, East Flanders, Antwerp, Flemish Brabant and Limburg. The characteristics of these dialects are described by Timmermans [34] as follows. In the West Flanders dialect, vowels are produced with a more pronounced low and back position of the tongue, and consonants are produced with reduced articulatory contact (more softly). In East Flanders, vowels are mostly produced with a lower position of the tongue. The Brabant dialect is characterized by high (position of the tongue) and long
Flemish Normative Data on Nasalance Scores
(duration) vowels. In Antwerp, short vowels are produced longer (duration) and higher (position of the tongue). Some consonants are produced softly. In the Limburg dialect, all vowels are produced longer (duration) and most vowels lower (position of the tongue). Consonant production is characterized by deletion or soft production. Sometimes, the Antwerp and Limburg dialects are regarded as one dialect. However, because of the differences described above, they are considered as two different dialects [34]. In all dialects, coarticulation errors are made when compared with the standard language. Objective Assessment of Nasal Resonance Nasalance represents a measure of the relative amount of oral and nasal acoustic energy exhibited by a speaker [18]. It serves as an objective measure of perceived nasality. To determine nasalance, the Nasometer II (model 6450) was used. Oral and nasal components of speech are recorded by microphones placed on either side of a sound separator plate that is placed on the subject’s upper lip. Both signals are individually filtered and digitalized. The resultant signal is the ratio of nasal to nasal-plus-oral acoustic energy. The nasalance score (in percent) is calculated as the ratio of nasal to nasal-plus-oral acoustic energy multiplied by 100. Prior to data collection, the Nasometer was calibrated following the procedures outlined in the manual (KayPENTAX, 2010). Each subject was instructed to read three Dutch passages designed by van de Weijer and Slis [12] using habitual speech, pitch and loudness. The first passage, the oronasal text, contained the same percentage of nasal consonants (11.6%) as found in Dutch speech [42] and was similar to the English ‘rainbow’ passage of Fairbanks [43]. The second passage, the oral text, consisted exclusively of oral phonemes and is comparable to the ‘zoo’ passage of Fletcher and Bishop [2]. The last passage, the nasal text, contained a high percentage (57%) of nasal consonants and was used to detect hyponasality. Statistical Analysis To investigate the impact of gender and dialect, two-way ANOVA was used, with the variables gender and dialect as fixed factors.
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Table 2. Number of men and women enrolled from the five
Table 3. Nasalance scores for the oronasal, oral and nasal texts per
regional dialect
West Flanders East Flanders Antwerp Flemish Brabant Limburg
Table 4. Nasalance scores for the oronasal, oral and nasal texts in men and women and in the whole group
Oronasal text
Oral text
Nasal text
Oronasal text
Oral text
mean
SD
mean SD
mean SD
mean
SD
mean
SD
mean
SD
34 32 34 31 33
5 6 5 8 7
11 12 13 13 12
56 55 56 54 55
Men Women
32 34
7 6
12 13
5 5
54 56
7 7
Total
33 (11.8) 6
3 5 4 7 4
5 7 7 8 7
Nasal text
12 (9.8) 5
55 (13.8) 7
Values in parentheses denote PI. PI = Prediction interval.
The mean nasalance scores for the three reading texts for each dialect are presented in table 3. No significant differences between the five dialects were found for the oronasal text (p = 0.559, F = 0.750, d.f. = 4), the oral text (p = 0.803, F = 0.407, d.f. = 4) or the nasal text (p = 0.879, F = 0.297, d.f. = 4). The nasalance scores for men and women separately are presented in table 4. No significant differences were found between men and women for the oronasal text (p = 0.147, F = 2.120, d.f. = 1), the oral text (p = 0.395, F = 0.728, d.f. = 1) or the nasal text (p = 0.300, F = 1.082, d.f. = 1). Since no differences were found with regard to gender and dialect, normative data on the nasalance scores from the three passages were calculated for the whole group; they are presented in table 4.
Discussion
The purpose of this study was to obtain normative nasalance values for normal adult subjects as measured with the Nasometer II and to investigate the impact of gender and dialect. Dialect mainly has an influence on the production of vowels [32–34]. In the West Flanders dialect, vowels are produced with a more pronounced low and back position of the tongue [34]. In East Flanders, vowels are mostly produced with a lower position of the tongue. The Flemish Brabant dialect is characterized by high (position of the tongue) and long (duration) vowels. In Antwerp, short vowels are produced longer (duration) and higher (position of the tongue), and in the Limburg dialect all vowels are produced longer (duration) and most vowels lower (position of the tongue). From the literature, it is clear that nasality and nasalance scores are af46
Folia Phoniatr Logop 2015;67:42–48 DOI: 10.1159/000374110
fected by vowel content [35, 44]. Sentences with high vowels are produced more nasally and have higher nasalance scores compared to sentences with low vowels [35]. The highest nasalance scores and nasality ratings are found for high front vowels like /i/. Differences in nasalance scores are also found between high back vowels and low back and front vowels. Based on these differences in tongue position in the pronunciation of vowels in each dialect, significantly different nasalance scores were hypothesized between the dialects. Dialects characterized by vowels that are articulated with a more pronounced high and back position of the tongue (such as the Antwerp and the Flemish Brabant dialect) are hypothetically associated with higher nasalance values. Normative data were collected for the five regions corresponding to different specific dialects. No significant differences in nasalance scores were found between these dialects. These results are in accordance with the results of Kavanagh et al. [7] and Mishima et al. [4], who did not find any significant differences between variants of Japanese and Canadian English in adult speakers. In contrast, Awan et al. [37], Seaver et al. [22] and Nichols [31] found an impact of dialects of US English and Spanish on nasalance scores. There are some possible reasons why, in our study, no differences in nasalance scores were detected between the Flemish dialects. First of all, the results suggest that dialect has no impact on nasalance scores. The important implication of these results is that for clinical as well as scientific purposes, the specific dialect of the patient must not be taken into account when investigating nasalance. Today, most people in Flanders speak an attenuated form of their dialect that can be defined as an intermediate variety between the pure dialect and the standard language [45]. More extreme differences in dialects have possibly more impact on nasality and nasalance scores. However, the dialects were clearly distinguishable, as the speech of D’haeseleer/Bettens/De Mets/De Moor/ Van Lierde
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Results
the subjects in this study was perceptually judged in consensus by the two trained speech-language therapists. Moreover, it was a well-considered choice of the authors to instruct the subjects to use their habitual speech so that the normative data can be used for future clinical and scientific purposes. One cannot exclude the possibility that some subjects presented with a mixed dialect. To avoid mixed dialects, the inclusion criteria in this study were that subjects had to be born and raised in the same region and had to have self-reported speaking the dialect that was confirmed by the two speech-language therapists. Finally, a dialect can also be influenced by the subjects’ socioeconomic status, resulting in sociolects [46]. The impact of different sociolects on nasalance scores is the subject of further investigation. In future research, perceptual judgments of the dialects and nasality ratings should be made in a blinded fashion by a larger jury of speechlanguage pathologists so that reliability measurements can be included. Moreover, the speech stimuli can be enlarged by including vowels next to connected speech in studies regarding the impact of dialect on nasal resonance. The second purpose was to investigate the impact of gender on nasalance scores. Nasalance scores for the three reading text passages (oronasal, oral and nasal) were compared between men and women, and no differences were found. These results are in contrast to the results of Van Lierde et al. [18], who found higher nasalance scores in women for the oronasal and nasal texts. However, the differences between men and women were small (4.6 and 3.2%, respectively) and might possibly have been influenced by within-speaker variability. Other explanations for the contradictory results between the study by Van Lierde et al. [18] and the present study are the different sample sizes (n = 58 vs. 164), different materials (Nasometer model 6200 vs. Nasometer II model 6450) and different age groups (19–27 vs. 20–82 years). Also, for other
languages there is no consensus regarding the impact of gender on the nasalance scores of adults (table 1). When differences were found, women mostly had slightly higher nasalance scores than men (table 1). Since no differences were found with regard to gender or dialect in this study, nasalance scores were calculated for the whole group (table 4). The mean nasalance scores for the oronasal, oral and nasal texts as measured with the Nasometer II model 6450 were 33, 12 and 55, respectively. These normative data for the whole group only slightly differ from the Flemish normative data measured with the Nasometer model 6200 [18]. The differences in nasalance scores for the oronasal, oral and nasal texts are 0.8, 1.1 and 0.8, respectively, which is comparable to the differences that Watterson et al. [39] and de Boer and Bressman [41] found between the two models of the Nasometer. The normative nasalance scores for these text passages are also within the ranges of normative data reported for other languages (31–36% for oronasal, 10–16% for oral and 50–70% for nasal text passages) as measured with the two models of the Nasometer [3]. A large sample size was used in this study (n = 164). However, the sample sizes of each subgroup were not equally distributed (table 2). In future studies, equal numbers of subjects should be included in each group. Until now it has been uncertain if dialects in Flanders influence nasalance scores. Normative data on nasalance scores for Flemish measured with the Nasometer II were absent. This study provides new Flemish normative data on nasalance scores for oronasal, oral and nasal texts as measured with the Nasometer II model 6450. No differences regarding gender or dialect were found. The results of this study are very important for clinical purposes and for future Flemish studies collecting nasalance scores of subjects from the different regions. In the future, new norms should be used for each language when applying the Nasometer II.
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Flemish Normative Data on Nasalance Scores
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10 Haapanen ML: Nasalance scores in normal Finnish speech. Folia Phoniatr (Basel) 1991; 43:197–203. 11 Okalidou A, Karathanasi A, Grigoraki E: Nasalance norms in Greek adults. Clin Linguist Phon 2011;25:671–688. 12 van de Weijer J, Slis I: Nasality assessment using the Nasometer (in Dutch). Logop Foniatr 1991;63:97–101. 13 Santos Terrón MJ, Gonzalez-Landa G, Sánchez-Ruiz I: Normal patterns of nasalance in children who speak Castilian (in Spanish). Rev Esp Foniatr 1991;4:71–75. 14 Prathanee B, Thanaviratananich S, Pongjunyakul A, Rengpatanakij K: Nasalance scores for speech in normal Thai children. Scand J Plast Reconstr Surg Hand Surg 2003;37:351– 355. 15 Sarac ET, Kayikci MEK, Ozkan S: Nasality evaluation of Turkish phonemes in vowelconsonant combinations. Int J Pediatr Otorhinolaryngol 2011;75:894–898. 16 Park M, Baek WS, Lee E, Koh KS, Kim BK, Baek R: Nasalance scores for normal Koreanspeaking adults and children. J Plast Reconstr Aesthet Surg 2014;67:173–177. 17 Tachimura T, Mori C, Hirata S, Wada T: Nasalance score variation in normal adult Japanese speakers of Mid-West Japanese dialect. Cleft Palate Craniofac J 2000;37:463–467. 18 Van Lierde KM, Wuyts FL, De Bodt M, Van Cauwenberge P: Age-related patterns of nasal resonance in normal Flemish children and young adults. Scand J Plast Reconstr Surg Hand Surg 2003;37:344–350. 19 Rochet AP, Sovis EA, Mielke DL: Characteristics of nasalance in speakers of Western Canadian English and French. J Speech Lang Pathol Audiol 1998;22:94–103. 20 Abou-Elsaad T, Quriba A, Baz H, Elkassaby R: Standardization of nasometry for normal Egyptian Arabic speakers. Folia Phoniatr Logop 2012;64:271–277. 21 D’haeseleer E, Depypere H, Claeys S, Van Lierde KM: Nasal resonance in middle-aged women: a multiparameter approach. Ann Otol Rhinol Laryngol 2011;120:575–580.
Published online: May 19, 2015
Normative Data and Dialectical Effects on Nasalance in Flemish Adults Evelien D’haeseleer Kim Bettens Sarah De Mets Valerie De Moor Kristiane Van Lierde Department of Speech-, Language- and Hearing Sciences, Ghent University, Ghent, Belgium
Abstract Objective: The purpose of this study was to investigate the impact of dialect and gender and to obtain normative nasalance values for Flemish adults as measured with the Nasometer II. Subjects and Methods: One hundred and sixtyfour adult subjects from the five regions in Flanders corresponding to different dialects were included in the study. The group consisted of 71 adult men and 93 adult women with a mean age of 43 years and an age range between 20 and 82 years (SD 16). Nasalance scores of connected speech using an oral, an oronasal and a nasal text were measured with the Nasometer II model 6450. Results: The nasalance scores for the oral, oronasal and nasal texts are provided in this study. No significant differences were found across the five dialects and between men and women. Conclusion: This study provides new Flemish normative data as measured with the Nasometer II model 6450. The results of this study are very important for clinical purposes and for future Flemish studies collecting nasalance scores of subjects with different dialects. © 2015 S. Karger AG, Basel
© 2015 S. Karger AG, Basel 1021–7762/15/0671–0042$39.50/0 E-Mail [email protected] www.karger.com/fpl
Introduction
To measure the degree of nasality, perceptual as well as objective measurements are used and described in the literature [1]. Nasometry, originally developed by Fletcher and Bishop [2], is an effective diagnostic tool for detecting abnormalities in nasal resonance [1]. Different instruments for nasometry exist, of which the Nasometer is the one most frequently reported in the literature [3]. The system is easy to use because of its speed, noninvasiveness, objectivity and reliability [4, 5]. In the literature, normative data are available for variants of English, French, Cantonese, German, Finnish, Greek, Hungarian, Dutch, Spanish, Thai, Turkish, Swedish, Korean, Japanese and Flemish [3, 5–18]. Controversy exists about the influence of age, gender and dialect on nasalance scores as measured by the Nasometer [4, 6, 18– 31]. Regarding the impact of gender on nasalance, studies report higher nasalance scores in women [4, 6, 18–20, 22], due to anatomical and physiological differences between men and women [22] or differences in coarticulation [28]. Other studies have not reported any differences in nasalance scores between men and women [5, 7, 11, 17, 29–31]. Evelien D’haeseleer Department of Speech-, Language- and Hearing Sciences Ghent University, De Pintelaan 185, 2P1 BE–9000 Ghent (Belgium) E-Mail Evelien.Dhaeseleer @ ugent.be
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Key Words Nasalance · Dialect · Normative data · Flemish
Dialects can be discriminated by differences in sound system (pronunciation), vocabulary and grammar [32]. In English as well as in Flemish, dialect mainly has an influence on the production of vowels [32–34]. Vowels can be described in terms of high/low and front/back placement of the tongue in the oral cavity. Studies have shown that these differences in tongue placement can influence nasalance scores [35, 36]. Therefore, dialectical variations should be taken into account when studying nasal resonance. Differences in nasalance scores per dialect have been reported by Seaver et al. [22], Mayo et al. [30], Nichols [31] and Awan et al. [37]. Table 1 summarizes the literature regarding the impact of dialect and gender on nasalance scores in adults. Seaver et al. [22] investigated nasalance in four geographical regions of North America and found significantly higher nasalance scores for MidAtlantic English speakers. Between the other regions, very little difference was observed. Mayo et al. [30] studied nasalance in two races (African American/White American) speaking a Mid-Atlantic dialect of American English. They found significantly higher nasalance scores among the white speakers and hypothesized that these differences may be related to the cultural-linguistic background (rather than race). In a study by Nichols [31], differences in nasalance between Spanish speakers from two cities in Central Mexico were measured. Significant but small differences (3%) in mean nasalance scores were observed between the two cities. It is, however, unclear whether dialect can explain these differences. In a recent study, Awan et al. [37] investigated dialectical effects on nasalance in six different North American dialects. The effect sizes for dialect were moderate in strength and accounted for approximately 7–9% of the variation in nasalance. The highest nasalance rates were found in the Texas South dialectal region. They concluded that clinicians and researchers should be aware that dialectal speech patterns may influence nasalance values as well as the interpretation of normative expectations and typical versus disordered cutoff scores. Other authors have not found any impact of dialect on differences in nasalance by dialect [4, 7]. For Dutch and Flemish, no studies investigating the impact of dialect have been published. From the literature, it is clear that nasalance scores are language dependent [38]. Therefore, differences regarding age, gender and dialect should be investigated per language. Further variation is caused by the model of Nasometer used; studies have shown a variation of 1 or 2 points between the Nasometer model 6200, mostly used in previous studies, and the new models of the Nasometer
II (6400 and 6450) [39–41]. Although differences between the two models are not clinically relevant, Kummer [40] concluded that new norms should be used with the Nasometer II models 6400 and 6450. For Flemish (the language spoken in the northern part of Belgium), the impact of age on nasalance scores has already been investigated. Van Lierde et al. [18] investigated the differences in nasalance scores between Flemish children and adults and found that young adults had higher nasalance scores than children, particularly when the stimuli included nasal consonants. Between young and older adults, no differences in nasalance scores were found for Flemish [21]. The impact of gender on nasalance in the Flemish language was also investigated by Van Lierde et al. [18], and significantly higher scores were reported for women. However, none of the above-mentioned studies account for the possible influence of dialect on nasalance values in the Flemish language. From the literature it is clear that, in some cases, dialect can influence nasalance scores (table 1). For the future interpretation of nasalance data in clinical Flemish studies and for clinical practice, normative data on each dialect are necessary. The purpose of this study was to obtain normative nasalance values with the Nasometer II from a group of 164 normal adults. Secondly, the impact on nasalance of gender and dialect was investigated by comparing the nasalance scores between women and men and between speakers of the five dialects in Flanders (West Flanders, East Flanders, Antwerp, Flemish Brabant and Limburg). It was hypothesized that gender and the five Flemish dialects would have a significant impact on the nasalance scores.
Flemish Normative Data on Nasalance Scores
Folia Phoniatr Logop 2015;67:42–48 DOI: 10.1159/000374110
Subjects and Methods
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Participants Hundred and sixty-seven adult subjects from the five regions in Flanders corresponding to different dialects were included in the study. In Flanders, the five different dialectical regions with their corresponding specific dialects are West Flanders, East Flanders, Antwerp, Flemish Brabant and Limburg, as described by Timmermans [34]. The inclusion criteria for each dialect were very strict. The subjects included (1) had to be born and raised in the same region and (2) had to have self-reported speaking the specific dialect. Two speech-language therapists with 4 years of experience in detecting Flemish dialects perceptually judged their speech, and both confirmed the dialects in consensus. All subjects reported to have a normal hearing, a normal speech and language development, good general health and no history of speech therapy for a resonance disorder. Patients with nasal congestion or a cold at the moment of testing were excluded from the study (n = 3).
Table 1. Summary of the literature on the impact of dialect and gender on nasalance in adults Language
Gender M/F, n
Age, years
Hutchinson et al. [6], 1978
English
30/30
Seaver et al. [22], 1991
English in four 56/92 geographical regions of North America
Speech sample
Material
Effect of gender
Effect of dialect
50 – 80 Oral text; oronasal text; nasal text
Tonar II
Significantly higher scores in women
–
16 – 63 Oral text; oronasal text; nasal text
Nasometer 6200
Significantly higher scores in women for nasal sentences
Significantly higher nasalance scores were found in the MidAtlantic speakers for all three reading passages; very little difference was observed for three of the four regional speech patterns
Litzaw and English Dalston [29], 1992
15/15
>18
Oral text; oronasal text; nasal text
Nasometer 6200
No significant – differences between men and women
Kavanagh et al. [7], 1994
English, three Canadian dialects
16/36
18 – 33 Oral text; oronasal text; nasal text
Nasometer 6200
No differences between men and women
No differences in dialect
Mayo et al. [30], 1996
Mid-Atlantic dialect 40/40 of American English in two races (African American/White American)
>18 Oral text; (mean: nasal text 23)
Nasometer 6200
No differences between men and women
Significantly higher nasalance scores among the White American speakers; these differences may be related to the cultural-linguistic background (rather than race)
Rochet et al. [19], 1998
English and French
60/93
9 – 85
Oral text; oronasal text; nasal text
Nasometer 6200
Significantly higher scores in women for the oronasal text in English and the oronasal and nasal texts in French
–
Nichols [31], Spanish spoken in 1999 two cities in central Mexico
24/31
20 – 40 Oral text; oronasal text
Nasometer 6200
No differences in mean nasometric values between men and women; the minima of the oronasal text of women were significantly higher
Significant differences in mean nasalance scores for the oral text between the two cities (16 vs. 19%); it is, however, unclear whether dialect can explain these differences
Tachimura et al. [17], 2000
Japanese
50/50
19 – 35 Oral text
Nasometer 6200
No significant – differences between men and women
Van Lierde et al. [18], 2003
Flemish
28/30
19 – 27 Oral text; oronasal text; nasal text; vowels
Nasometer 6200
Significantly higher scores in women for the oronasal and nasal texts and the vowel /u/
Hirschberg et al. [5], 2006
Hungarian
75
5 – 25
Mishima et al. [4], 2008
Japanese in four regions: Chugoku, Kinki, Shikoku, other regions
31/37
Mean: Oral text; 23 vowels
Nasometer II 6400 Significantly higher scores in women for the oral text and the vowels
Okalidou et al. [11], 2011
Greek
40/40
18 – 34 Oral text; oronasal text; nasal text; SNAP test
Nasometer 6200-3
44
Nasometer 6400 Phonemes; syllables; oral sentence; oronasal sentence; nasal sentence
Folia Phoniatr Logop 2015;67:42–48 DOI: 10.1159/000374110
–
No significant – differences between men and women
No significant differences between the three regional dialects
No significant – differences between men and women
D’haeseleer/Bettens/De Mets/De Moor/ Van Lierde
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Study
Table 1 (continued) Study
Language
Gender M/F, n
Age, years
Abou-Elsaad Arabic et al. [20], 2012
62/70
18 – 54 SNAP test
Awan et al. [37], 2015
150/150 Mean: Oral text; 22 oronasal text; nasal text
English in six North American dialectal regions
Speech sample
Material
Effect of gender
Effect of dialect
Nasometer II 6400 Significantly higher scores in women
–
Nasometer II 6400 Significantly higher scores in women
Significant differences for dialect; the effect sizes for dialect were moderate in strength and accounted for approx. 7 – 9% of the variation in nasalance; the highest nasalance scores were found in the Texas South dialectal region
SNAP = Simplified Nasometric Assessment Procedures.
different Flemish dialectal regions Region
Men
Women
Total
West Flanders East Flanders Antwerp Flemish Brabant Limburg
13 25 6 15 12
17 25 16 17 18
30 50 22 32 30
The two speech-language therapists also perceptually judged the speech in consensus to detect abnormalities in resonance and articulation. Resonance was categorized as normal, hyponasal (mild, moderate or severe) or hypernasal (mild, moderate or severe), and articulation was rated as normal or abnormal (mild, moderate or severe). In all subjects, resonance and articulation were normal. The final group consisted of 164 subjects (167 minus 3 subjects with nasal congestion or a cold), 71 adult men and 93 adult women with a mean age of 43 years and an age range between 20 and 82 years (SD 16). Table 2 presents the number of men and women enrolled from the five different regions. Dialects Dialectal boundaries are established when there is a tendency for the majority of speakers in one region the use the same patterns of vowel production [37]. In Flanders, the five different dialectal regions are West Flanders, East Flanders, Antwerp, Flemish Brabant and Limburg. The characteristics of these dialects are described by Timmermans [34] as follows. In the West Flanders dialect, vowels are produced with a more pronounced low and back position of the tongue, and consonants are produced with reduced articulatory contact (more softly). In East Flanders, vowels are mostly produced with a lower position of the tongue. The Brabant dialect is characterized by high (position of the tongue) and long
Flemish Normative Data on Nasalance Scores
(duration) vowels. In Antwerp, short vowels are produced longer (duration) and higher (position of the tongue). Some consonants are produced softly. In the Limburg dialect, all vowels are produced longer (duration) and most vowels lower (position of the tongue). Consonant production is characterized by deletion or soft production. Sometimes, the Antwerp and Limburg dialects are regarded as one dialect. However, because of the differences described above, they are considered as two different dialects [34]. In all dialects, coarticulation errors are made when compared with the standard language. Objective Assessment of Nasal Resonance Nasalance represents a measure of the relative amount of oral and nasal acoustic energy exhibited by a speaker [18]. It serves as an objective measure of perceived nasality. To determine nasalance, the Nasometer II (model 6450) was used. Oral and nasal components of speech are recorded by microphones placed on either side of a sound separator plate that is placed on the subject’s upper lip. Both signals are individually filtered and digitalized. The resultant signal is the ratio of nasal to nasal-plus-oral acoustic energy. The nasalance score (in percent) is calculated as the ratio of nasal to nasal-plus-oral acoustic energy multiplied by 100. Prior to data collection, the Nasometer was calibrated following the procedures outlined in the manual (KayPENTAX, 2010). Each subject was instructed to read three Dutch passages designed by van de Weijer and Slis [12] using habitual speech, pitch and loudness. The first passage, the oronasal text, contained the same percentage of nasal consonants (11.6%) as found in Dutch speech [42] and was similar to the English ‘rainbow’ passage of Fairbanks [43]. The second passage, the oral text, consisted exclusively of oral phonemes and is comparable to the ‘zoo’ passage of Fletcher and Bishop [2]. The last passage, the nasal text, contained a high percentage (57%) of nasal consonants and was used to detect hyponasality. Statistical Analysis To investigate the impact of gender and dialect, two-way ANOVA was used, with the variables gender and dialect as fixed factors.
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Table 2. Number of men and women enrolled from the five
Table 3. Nasalance scores for the oronasal, oral and nasal texts per
regional dialect
West Flanders East Flanders Antwerp Flemish Brabant Limburg
Table 4. Nasalance scores for the oronasal, oral and nasal texts in men and women and in the whole group
Oronasal text
Oral text
Nasal text
Oronasal text
Oral text
mean
SD
mean SD
mean SD
mean
SD
mean
SD
mean
SD
34 32 34 31 33
5 6 5 8 7
11 12 13 13 12
56 55 56 54 55
Men Women
32 34
7 6
12 13
5 5
54 56
7 7
Total
33 (11.8) 6
3 5 4 7 4
5 7 7 8 7
Nasal text
12 (9.8) 5
55 (13.8) 7
Values in parentheses denote PI. PI = Prediction interval.
The mean nasalance scores for the three reading texts for each dialect are presented in table 3. No significant differences between the five dialects were found for the oronasal text (p = 0.559, F = 0.750, d.f. = 4), the oral text (p = 0.803, F = 0.407, d.f. = 4) or the nasal text (p = 0.879, F = 0.297, d.f. = 4). The nasalance scores for men and women separately are presented in table 4. No significant differences were found between men and women for the oronasal text (p = 0.147, F = 2.120, d.f. = 1), the oral text (p = 0.395, F = 0.728, d.f. = 1) or the nasal text (p = 0.300, F = 1.082, d.f. = 1). Since no differences were found with regard to gender and dialect, normative data on the nasalance scores from the three passages were calculated for the whole group; they are presented in table 4.
Discussion
The purpose of this study was to obtain normative nasalance values for normal adult subjects as measured with the Nasometer II and to investigate the impact of gender and dialect. Dialect mainly has an influence on the production of vowels [32–34]. In the West Flanders dialect, vowels are produced with a more pronounced low and back position of the tongue [34]. In East Flanders, vowels are mostly produced with a lower position of the tongue. The Flemish Brabant dialect is characterized by high (position of the tongue) and long (duration) vowels. In Antwerp, short vowels are produced longer (duration) and higher (position of the tongue), and in the Limburg dialect all vowels are produced longer (duration) and most vowels lower (position of the tongue). From the literature, it is clear that nasality and nasalance scores are af46
Folia Phoniatr Logop 2015;67:42–48 DOI: 10.1159/000374110
fected by vowel content [35, 44]. Sentences with high vowels are produced more nasally and have higher nasalance scores compared to sentences with low vowels [35]. The highest nasalance scores and nasality ratings are found for high front vowels like /i/. Differences in nasalance scores are also found between high back vowels and low back and front vowels. Based on these differences in tongue position in the pronunciation of vowels in each dialect, significantly different nasalance scores were hypothesized between the dialects. Dialects characterized by vowels that are articulated with a more pronounced high and back position of the tongue (such as the Antwerp and the Flemish Brabant dialect) are hypothetically associated with higher nasalance values. Normative data were collected for the five regions corresponding to different specific dialects. No significant differences in nasalance scores were found between these dialects. These results are in accordance with the results of Kavanagh et al. [7] and Mishima et al. [4], who did not find any significant differences between variants of Japanese and Canadian English in adult speakers. In contrast, Awan et al. [37], Seaver et al. [22] and Nichols [31] found an impact of dialects of US English and Spanish on nasalance scores. There are some possible reasons why, in our study, no differences in nasalance scores were detected between the Flemish dialects. First of all, the results suggest that dialect has no impact on nasalance scores. The important implication of these results is that for clinical as well as scientific purposes, the specific dialect of the patient must not be taken into account when investigating nasalance. Today, most people in Flanders speak an attenuated form of their dialect that can be defined as an intermediate variety between the pure dialect and the standard language [45]. More extreme differences in dialects have possibly more impact on nasality and nasalance scores. However, the dialects were clearly distinguishable, as the speech of D’haeseleer/Bettens/De Mets/De Moor/ Van Lierde
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Results
the subjects in this study was perceptually judged in consensus by the two trained speech-language therapists. Moreover, it was a well-considered choice of the authors to instruct the subjects to use their habitual speech so that the normative data can be used for future clinical and scientific purposes. One cannot exclude the possibility that some subjects presented with a mixed dialect. To avoid mixed dialects, the inclusion criteria in this study were that subjects had to be born and raised in the same region and had to have self-reported speaking the dialect that was confirmed by the two speech-language therapists. Finally, a dialect can also be influenced by the subjects’ socioeconomic status, resulting in sociolects [46]. The impact of different sociolects on nasalance scores is the subject of further investigation. In future research, perceptual judgments of the dialects and nasality ratings should be made in a blinded fashion by a larger jury of speechlanguage pathologists so that reliability measurements can be included. Moreover, the speech stimuli can be enlarged by including vowels next to connected speech in studies regarding the impact of dialect on nasal resonance. The second purpose was to investigate the impact of gender on nasalance scores. Nasalance scores for the three reading text passages (oronasal, oral and nasal) were compared between men and women, and no differences were found. These results are in contrast to the results of Van Lierde et al. [18], who found higher nasalance scores in women for the oronasal and nasal texts. However, the differences between men and women were small (4.6 and 3.2%, respectively) and might possibly have been influenced by within-speaker variability. Other explanations for the contradictory results between the study by Van Lierde et al. [18] and the present study are the different sample sizes (n = 58 vs. 164), different materials (Nasometer model 6200 vs. Nasometer II model 6450) and different age groups (19–27 vs. 20–82 years). Also, for other
languages there is no consensus regarding the impact of gender on the nasalance scores of adults (table 1). When differences were found, women mostly had slightly higher nasalance scores than men (table 1). Since no differences were found with regard to gender or dialect in this study, nasalance scores were calculated for the whole group (table 4). The mean nasalance scores for the oronasal, oral and nasal texts as measured with the Nasometer II model 6450 were 33, 12 and 55, respectively. These normative data for the whole group only slightly differ from the Flemish normative data measured with the Nasometer model 6200 [18]. The differences in nasalance scores for the oronasal, oral and nasal texts are 0.8, 1.1 and 0.8, respectively, which is comparable to the differences that Watterson et al. [39] and de Boer and Bressman [41] found between the two models of the Nasometer. The normative nasalance scores for these text passages are also within the ranges of normative data reported for other languages (31–36% for oronasal, 10–16% for oral and 50–70% for nasal text passages) as measured with the two models of the Nasometer [3]. A large sample size was used in this study (n = 164). However, the sample sizes of each subgroup were not equally distributed (table 2). In future studies, equal numbers of subjects should be included in each group. Until now it has been uncertain if dialects in Flanders influence nasalance scores. Normative data on nasalance scores for Flemish measured with the Nasometer II were absent. This study provides new Flemish normative data on nasalance scores for oronasal, oral and nasal texts as measured with the Nasometer II model 6450. No differences regarding gender or dialect were found. The results of this study are very important for clinical purposes and for future Flemish studies collecting nasalance scores of subjects from the different regions. In the future, new norms should be used for each language when applying the Nasometer II.
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Flemish Normative Data on Nasalance Scores
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