Relationship between perceptual ratings of nasality and nasometry in ...

INT. J. LANG. COMM. DIS., MAY–JUNE VOL.

43,

NO.

2008,

3, 265–282

Relationship between perceptual ratings of nasality and nasometry in children/adolescents with cleft palate and/or velopharyngeal dysfunction Triona Sweeney{ and Debbie Sell{ {The Children’s University Hospital, Dublin, Ireland {Great Ormond Street Hospital Trust for Children, London (Received 11 October 2006; revised 22 February 2006; accepted 8 May 2007)

Abstract Background: Nasometry has supplemented perceptual assessments of nasality, using speech stimuli, which are devoid of nasal consonants. However, such speech stimuli are not representative of conversational speech. A weak relationship has been found in previous studies between perceptual ratings of hypernasality and nasalance scores for passages containing nasal consonants. Aims: This study aimed to evaluate the relationship between perceptual assessment and acoustic measurements of nasality using controlled speech stimuli. Methods & Procedure: A perceptual scale (the Temple Street Scale) describing nasality was devised for this study. Fifty children presenting with nasality were assessed using the Temple Street Scale and nasalance scores were obtained for specified speech samples using the Nasometer (Kay Elemetrics 6200.3). The relationship between the perceptual ratings and the nasometry results was evaluated using correlation analysis, test sensitivity, specificity, and overall efficiency. Outcomes & Results: Correlation coefficients for perceptual ratings of nasality and nasalance scores ranged from 0.69 to 0.74. The sensitivity of the Nasometer ranged from 0.83 to 0.88; its specificity ranged from 0.78 to 0.95; while its overall efficiency was between 0.82 and 0.92. Conclusions: The strong relationship between perceptual and acoustic assessments of nasality indicated that the Temple Street Scale and the Nasometer are both valid clinical tools for the evaluation of nasality when a carefully constructed speech sample is used. The need to use the Nasometer as a supplement to perceptual assessment is highlighted. Keywords: velopharyngeal dysfunction, perceptual assessment, nasality, Nasometer.

Address correspondence to: Triona Sweeney, The Children’s University Hospital, Temple Street, Dublin 1, Ireland; e-mail: [email protected]

International Journal of Language & Communication Disorders ISSN 1368-2822 print/ISSN 1460-6984 online # 2008 Royal College of Speech & Language Therapists http://www.informahealthcare.com DOI: 10.1080/13682820701438177

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Triona Sweeney and Debbie Sell

What this paper adds What is already known on this subject Perceptual assessment of nasality has some difficulties including the definition of terms, reliability and the use of different types of scales. Nasometry has been used to supplement perceptual assessments of nasality. Speech stimuli, which are devoid of nasal consonants, have been used for nasometric evaluations and a good relationship has been reported between perceptual ratings of hypernasality and nasalance scores for such passages. However, a weak relationship has been found between perceptual ratings of hypernasality and nasalance scores for passages containing nasal consonants. What this study adds This paper provides a descriptive scale for the assessment of nasality, which addresses some of the limitations of previous perceptual assessments. It describes a speech sample suitable for perceptual and nasometric assessment of hypernasality. This is the first study to find a strong relationship between perceptual ratings of nasality and nasalance scores for speech stimuli containing all consonant types. The study highlights factors that may influence the relationship between perceptual and nasometric assessments.

Introduction Speech has long been recognized as one of the primary outcome measures of palatal surgery (Grunwell et al. 1993). In order to make decisions about: the need for modification of oral structures, the appropriateness of speech intervention, and the planning and execution of therapeutic procedures. (McWilliams et al. 1990: 3)

an in-depth assessment of speech production is essential. The perceptual assessment of nasality constitutes an important aspect of a comprehensive assessment of the speech of individuals with repaired cleft palate and/or velopharyngeal dysfunction (McWilliams et al. 1990, Sell et al. 1999). Indeed Kuehn (1982: 518) states that, ‘in a sense, a speech disorder does not exist until it is perceived by a listener’. Perceptual assessment not only serves to evaluate the speech status of individuals, but also indirectly provides information about velopharyngeal function in the absence of oral/nasal fistulae in the cleft palate population (Moon 1993). Hence, there is a need for a reliable and valid comprehensive protocol for assessing speech. Although it is now acknowledged that the perceptual assessment is the gold standard for assessment of speech disorders related to cleft palate and velopharyngeal dysfunction (Kuehn and Moller 2000), it is also acknowledged there are confounding problems with this approach (Kent 1996, Sell et al. 1999, John et al. 2006). For the perceptual assessment of nasality one area of controversy is the type of rating scale used. Rating scales, using descriptive category judgements (such as mild, moderate and severe) and equal interval scaling, are the favoured approach (Sell 2005). However, there is less agreement regarding the number of points in the scale, which may range from a four-point scale to a nine-point or even an 11-point scale (Whitehill 2004). Kent (1996) also reports the lack of definitions of terms used in such scales. This according to Wirz and Mackenzie Beck (1995) may result in poor

Perceptual ratings of nasality and nasometry scores

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test–retest and inter-judge reliability. Hence, reaching agreement about definition of terms is an important step forward (John et al. 2006). John et al. report that although there are many clinical assessments of nasality in use, few have been rigorously evaluated for reliability and validity. Hayden and Klimacka (2000) studied inter-rater reliability for a simple categorical scale of hypernasality and reported good correlations for experienced listeners ranging from 0.88 to 0.97. Importantly the categorical scale did not contain descriptors of each degree of severity of hypernasality. Furthermore, the correlations may be elevated as the authors do not state the type of the correlation used in the analysis. If rank correlation coefficients were used, the raters may have rated the speech samples in a similar manner, but this does not necessarily reflect the exact agreement on the scales, nor the influence of chance agreement of ratings. To date, no scale of hypernasality, which describes what the listener perceives, has been described in the literature. The need for a carefully constructed standardized speech sample for perceptual assessment has been reported (Sell 2005). She stated that a speech sample including syllable repetition, sentence repetition, rote speech and a sample of conversational speech is useful for perceptual assessment. The importance of using a conversational speech sample has also been stressed in the literature (Grunwell et al. 1993, Kuehn and Moller 2000). Kuehn and Moller (2000) state that the conversational speech sample may provide important information about consistency or deterioration of articulation proficiency and changes in resonance characteristics. Hutters and Henningsson (2004) emphasized that the phonetic content of the speech sample may influence perception of hypernasality. Hence, careful consideration of the speech sample used for perceptual assessment of nasality is required. The Nasometer (Kay Elemetrics 1986) has been used both clinically and in research studies to measure the acoustic correlate of nasality. It measures oral and nasal acoustic sound signals through calculating a score, which represents the ratio of the energy in the two signals (Fletcher et al. 1989). Nasometry measures are useful for supplementing the speech and language therapist’s perception of hypernasal resonance in patients with velopharyngeal insufficiency (Dalston et al. 1991a, Watterson et al. 1996). Results of previous studies have indicated that factors such as language, dialect and the speech stimuli influence the scores obtained on the Nasometer (Seaver et al. 1991, Karnell 1995). The need to obtain normal nasalance scores for each dialect has been shown (Seaver et al. 1991, Sweeney et al. 2004). Speech stimuli, which are devoid of nasal consonants have been used for nasometric evaluations. Fletcher et al. (1989) stated that people with excessive nasalance showed a lower degree of association between the phonetic content of the speech sample and the nasalance scores. A greater difference in nasalance scores was found between normal and hypernasal speakers when the speech sample was devoid of nasal consonants (Fletcher 1978). These findings add to our knowledge about phonetic content and nasalance scores. Several studies have reported a good relationship between perceptual ratings of hypernasality and nasalance scores for such passages, with correlation coefficients ranging from 0.70 (Watterson et al. 1996) to 0.82 (Dalston et al. 1991a). Other studies have reported weaker relationships, with correlation coefficients ranging from 0.49 (Watterson et al. 1993) to 0.66 (Paynter et al. 1991). However, a speech sample devoid of nasal consonants is not representative of normal speech and may well represent a biased sample for assessment of hypernasality. It has been shown that phonetic context may affect velopharyngeal function (Kuehn and Moon 1998) and possibly perception of hypernasality (Hutters and Henningsson

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2004). Therefore a speech sample, which represents the content of spontaneous speech, may have greater face validity. Previous nasometry studies have indicated a weak relationship between perceptual ratings of hypernasality and nasalance scores for passages containing 11% nasal consonants, which is representative of the distribution of nasal consonants in conversational speech in English (Fletcher et al. 1989, Dalston and Seaver 1992). For example, Watterson et al. (1996) reported a correlation coefficient of 0.32 between perceptual ratings and nasalance scores on the Mouse Passage, while Keuning et al. (2002) reported a mean correlation coefficient of 0.57 between perceptual ratings of hypernasality and nasalance scores for a speech sample containing the normal distribution of phonemes in the Dutch language. Karnell (1995) suggested that separate nasalance scores should be obtained for high-pressure and low-pressure consonant sentences if participants exhibit nasal airflow errors as well as resonance problems. He hypothesized that a speech sample devoid of nasal consonants and oral pressure consonants (i.e. low-pressure consonant sample) would enable measurement of nasal acoustic energy that is due to nasal resonance and not influenced by turbulent nasal airflow. Watterson et al. (1998a) assessed 25 children, five with normal speech and 20 children who had nasal emission diagnosed using a mirror test. They found no significant difference between nasalance scores for highpressure consonant sentences (30.28%) and mean nasalance scores for the low-pressure consonant sentences (28.98%). However, it is noteworthy that the authors had not carried out any perceptual assessment of nasal emission/nasal turbulence. Nasometry has also been used to identify patients with hyponasality and/or nasal airway impairment (Dalston et al. 1991b). Dalston et al. evaluated the sensitivity and specificity of the Nasometer in correctly identifying the presence or absence of hyponasality. Test sensitivity refers to the percentage of participants who are identified as having abnormal speech on one test and who are also identified as having abnormal speech on another test. Test specificity refers to the percentage of patients who are identified as having normal speech on one test and who are also identified as having normal speech on another test. Dalston et al. (1991b) reported sensitivity of the Nasometer in correctly identifying the presence or absence of hyponasality was 0.48, and test specificity 0.79. However they found that when patients with audible nasal emission were excluded from the analysis, sensitivity rose to 1.0 and specificity rose to 0.85. No intra- or inter-judge reliability studies were carried out for perceptual judgements. Further investigations into the relationship between perceptual measurements and nasometric measurements and the effects of the speech stimuli on these relationships have been recommended (Karnell 1995). The aim of the present research was to compare a clinician’s perceptual ratings with nasometry measurements, for controlled speech samples, as performed and recorded according to the clinical protocol developed by the first author. Methods Participants The study cohort consisted of a consecutive series of 50 children and adolescents who had been referred to a national Cleft Lip and Palate Unit for investigation of speech problems. There were 30 males and 20 females (aged 4;10–15;10 years, mean age59;5 years, median age58;8 years). The criteria for inclusion were evidence of nasality and/or nasal airflow problems in speech indicating velopharyngeal

269


dysfunction and/or nasal obstruction of varying aetiology (table 1). The cohort included participants with normal nasality and varying degrees of hypernasality or hyponasality. Participants with or without a syndrome and with or without articulatory errors were included. Individuals were excluded if there was evidence of any of the following: severe dyspraxia/dysarthria; learning disability (greater than mild); bilateral hearing loss above 45 decibels at any frequency (audiological assessment within one month of the speech and nasometry assessments); an upper respiratory infection; moderate or severe hoarseness of voice; mixed nasal resonance; and an inability to complete the assessment protocol due to behavioural problems or poor cooperation. Speech sample A detailed speech sample was required for the perceptual assessment as the importance of assessing different levels or complexity of speech has been highlighted in the literature (Kuehn and Moller 2000). Therefore the speech sample for the perceptual assessment of nasality included: single words and syllables (which would also be included in other instrumental assessments); sentences that were adapted from the GOS.SP.ASS (Sell et al. 1999); automatic speech (‘Jack and Jill’, counting from one to 20 and from 60 to 70) and conversational speech (a minimum of 2 min) (see appendix 1). The 16 adapted GOS.SP.ASS test sentences were used for nasometric assessment; however, they were reordered according to consonant type, i.e. high-pressure consonants, low-pressure consonants, mixed consonants and nasal consonants (see appendix 2). The GOS.SP.ASS sentences were minimally adapted to include low-pressure consonants as Karnell (1995) recommended the use of separate low- and high-pressure consonant sentences in the nasometric assessment. The sentences were further adapted to ensure that the total test sentences contained 11% nasal consonants, which represents the distribution of nasal consonants in conversational speech in the English language (Fletcher et al. 1989). It was intended that the speech sample used for both the perceptual and Nasometric analysis would be similar, thereby reducing the variables that may influence the relationship between perceptual and nasometric scores. Procedures All participants were initially assessed for articulation errors using an adapted phonemic screening test (PACSTOYS; Grunwell and Harding 1995). Pictures of the Table 1. Diagnosis of the Study Cohort Classification Non-cleft velopharyngeal dysfunction Secondary cleft palate Submucous cleft palate Unilateral cleft lip and palate Bilateral cleft lip and palate Nasal obstruction 22Q11 deletion syndrome Adenoidal hypertrophy

Number of cases

%

24 13 4 3 2 2 1 1

48 26 8 6 4 4 2 2

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toys in this test were used to elicit single word utterances. The participants’ responses were transcribed phonetically and errors were summarized according to the Great Ormond Street Speech Assessment (GOS.SP.ASS ’98; Sell et al. 1999). The Temple Street Scale of Nasality and Nasal Airflow Errors (Temple Street Scale), which was developed by the author (T.S.) (see appendix 3), was used to rate hypernasality, hyponasality and nasal airflow errors. The descriptive ratings of severity of hypernasality and hyponasality are presented in figure 1. A summary of ratings of nasal airflow errors, articulation errors and any voice anomalies was recorded on the scale. The Temple Street Scale was evaluated for intra- and inter-rater reliability before the present study. Different groups to the study cohort were used in these studies in order to limit the burden of care for the study participants and their parents. Intrarater reliability of the Temple Street Scale was evaluated for the specialist speech and language therapist (T.S.) by rating the audio-recorded speech sample of 12 children presenting with nasality and/or nasal airflow errors on two occasions, with a 10week gap between ratings. The order of presentation of the 12 speech samples was randomized on both occasions by a therapist not involved with the study. Intra-rater reliability was calculated using percentage agreement and kappa scores for nasality (combined hypernasality and hyponasality) on the Temple Street Scale. Results indicated good intra-rater reliability (88% agreement and 0.7 kappa for ratings of nasality). Inter-rater reliability was evaluated for three speech and language therapists with varying experience (an experienced specialist in cleft palate (T.S.), an experienced speech and language therapist not specializing in cleft palate (Eilis

Figure 1. Temple Street Scale perceptual rating of nasality.


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Murphy) and an inexperienced therapist (Mary Pat O’Malley)). Perceptual ratings of the speech samples of 20 children were analysed and percentage agreement and kappa scores were calculated for each pair of raters. Results indicated fair to good inter-rater agreement for perceptual ratings of nasality (ranging from 77 to 85% agreement) and kappa scores (ranging from 0.4 to 0.6). For this study each participant repeated the speech sample for perceptual assessment. Perceptual ratings were carried out during a live assessment, by a specialist speech and language therapist (T.S.), using the Temple Street Scale (see appendix 3). Although it has been recommended that audio or video recording be used to evaluate clinical outcomes, live ratings are often used in clinical protocols (Sell 2005). As the aim of part of this study was to develop a clinical protocol for assessment of nasality it was suggested that the live judgement be used in the comparison of results to increase validity. Nasal resonance was measured using the Kay Nasometer model 6200.3. A headset, containing a sound separator with microphones on either side, detected the oral and nasal acoustic components of the participant’s speech. Before data collection, the Nasometer was calibrated at the beginning of each day, and then subsequently after every block of ten participants in accordance with recommendations of the manufacturers. The Nasometer mask was placed on the participant’s head in the appropriate position. Each participant was asked to repeat the 16 test sentences after the examiner. The sentences were recorded on the Nasometer in the following order to allow for detailed analysis according to type of sentence category (see appendix 2): 1–5: high-pressure consonants (devoid of nasal consonants). N Sentences Sentences 6 and 7: low-pressure consonants (devoid of high-pressure and N nasal consonants). 8–15: mixed category contained (all consonant types but more N Sentences than 11% nasal consonants). N Sentence 16: nasal consonants (55% nasal consonants). During data collection each sentence was captured on the Nasometer with a one second gap between them which allowed the examiner to switch the data collection on and off. A 5 s gap was left between each sentence category in order subsequently to identify the separate sentence categories for analysis. Test–retest reliability of the Nasometer was evaluated before this study by obtaining nasalance scores twice for ten normal speakers during production of the 16 total test sentences (Sweeney et al. 2004). The headset was not removed during this process, but was checked to ensure appropriate placement before the repetition of the second set of sentences. Data were analysed using Generalizability Theory to obtain reliability coefficients (Streiner and Norman 1995). Results indicated good test–retest reliability for the total test sentences (0.73), high-pressure consonant sentences (0.83), and low-pressure consonant sentences (0.74). Analysis indicated that 100% of mean nasalance scores for the total test sentences were within 4 percentage points of the score on the second repetition of the sentences. Reliability for the nasal sentence was weak (0.15); however, inspection of the data indicated that 90% of mean nasalance scores were within 5 percentage points of the score during repetition of the Nasal sentence. These results are similar to those reported by Seaver et al. (1991).

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Triona Sweeney and Debbie Sell Data analysis

The severity of hypernasality and hyponasality for 50 children was rated according to the Temple Street Scale (see appendix 3). Mean nasalance scores were obtained for four sentence categories: total test sentences, high-pressure consonant sentences, low-pressure consonant sentences, and a nasal sentence. The mean nasalance score for the 16 total test sentences was calculated by analysing all data. The mean nasalances for high-pressure consonant sentences and low-pressure consonant sentences were obtained by marking the beginning and end of each of these sentence categories with cursors using a display duration of 20 s, and measuring the data between the cursors. The mean nasalance scores for the nasal sentence were obtained marking the sentence in a similar way. Statistical analysis The relationship between nasalance scores and perceptual ratings of nasality was calculated using the Pearson product moment correlation. All correlation analyses were two tailed (a50.05). Test sensitivity (true positive rate) and specificity (true negative rate) were calculated using a cut-off value for perceptual ratings of hypernasality .1 (where 1 was defined as mild hypernasality, evident but acceptable, not requiring further investigation or management). A nasalance cut-off value for each sentence category was calculated statistically, using nasalance scores of two standard deviations above the mean normal scores (Sweeney et al. 2004). Hence, the cut-off score for the total test sentences was 35%, for high-pressure consonant sentences was 24% and for low-pressure consonant sentences was 28%. For the Nasal Sentence a cut-off score of 2 standard deviations (SDs) below the mean normal score was used (36%). An overall efficiency rating was calculated by adding the number of times perceptual ratings agreed with nasometric scores, divided by the total number of opportunities (i.e. total number of participants tested) (Watterson et al. 1998a). Results The study cohort presented with various aetiologies including cleft palate, non-cleft velopharyngeal dysfunction and nasal obstruction (table 1). Participants presented with a wide range of nasality results (table 2). All the perceptual and nasometric results are presented in table 3. Correlation analyses for the relationship between perceptual ratings of nasality and nasalance scores for each sentence category are presented in table 4. Results indicated a substantial positive relationship between perceptual ratings of hypernasality and nasalance scores on the total test sentences (correlation coefficient50.74, p,0.001) and between ratings of hypernasality and nasalance scores on high-pressure consonant sentences (correlation coefficient50.74, p,0.001). A weaker but significant relationship was found between perceptual ratings of hypernasality and nasalance scores on low-pressure consonant sentences (correlation coefficient50.69, p,0.001). There was a strong negative correlation between perceptual ratings of hyponasality and nasalance scores on the nasal sentence (correlation coefficient520.76, p,0.001).

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Perceptual ratings of nasality and nasometry scores Table 2. Perceptual ratings of nasality for the study group, with descriptions Per cent of study group

Number of participants

Hypernasality Absent Evident but acceptable Unacceptable distortion, evident on high vowels Evident on high and low vowels Evident on all vowels and some consonants Evident on all vowels and most voiced consonants

20 4 38 16 12 6

10 4 19 8 6 3

Hyponasality Absent Evident but acceptable Evident on all vowels and some consonants

86 4 10

43 2 5

Speech descriptor

Table 3. Raw score values for all participants for perceptual ratings of hypernasality and hyponasality, and nasalance sores for 16 adapted GOPS.SP.Ass sentences (total test sentences), high-pressure consonant sentences, low-pressure consonant sentences, and the nasal sentence

ID

Hypernasal

Nasalance total test sentences

1 2 3 4 5 6 8 10* 11 24* 13* 17 19 23 7* 9* 12* 14* 15* 16 21 27 29 32 33 35 37 39 40 41 42

0 0 0 0 0 0 0 0 0 0 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

5.24 6.35 7.19 7.64 19.85 22.11 25.01 27.70 28.70 40.11 30.45 34.91 36.19 39.63 24.29 26.06 30.25 30.65 30.93 32.54 36.97 43.36 46.58 47.69 48.90 50.90 51.70 53.57 53.59 54.19 54.35

Nasalance high-pressure consonants sentences

Nasalance low-pressure consonant sentences

Hyponasal

Nasalance nasal sentence

4.15 7.08 6.11 6.50 8.01 7.50 20.92 23.99 20.39 28.07 11.71 19.69 26.54 23.67 18.09 16.68 17.15 21.42 10.29 25.48 33.62 32.29 34.82 34.36 41.79 44.90 44.76 53.39 45.58 48.96 51.49

3.94 4.72 5.34 6.72 5.32 4.96 12.24 24.52 16.27 49.65 14.89 22.93 33.35 39.99 25.30 34.48 17.99 12.52 34.80 34.54 38.17 45.98 48.77 60.35 42.20 51.20 49.99 52.64 53.81 51.64 50.98

2 2 2 2 0 0 2 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

8.80 6.42 16.88 8.80 31.95 51.51 31.29 40.57 45.94 59.20 52.59 71.25 60.88 65.42 32.57 27.78 55.90 54.39 61.26 44.56 43.21 60.46 69.29 74.47 61.00 65.80 63.60 61.94 60.48 64.17 65.01

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Triona Sweeney and Debbie Sell Table 3. Continued.

ID

Hypernasal

Nasalance total test sentences

43 46 18* 20* 22* 26 28 31 38 47 25* 30 34 44 45 48 36 49 50

2 2 3 3 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5

54.89 56.41 35.69 36.67 37.41 42.64 44.56 47.48 52.83 58.23 40.55 46.70 50.34 55.36 55.96 60.02 51.20 63.30 67.51

Nasalance high-pressure consonants sentences

Nasalance low-pressure consonant sentences

Hyponasal

Nasalance nasal sentence

50.66 41.13 24.30 23.79 32.63 38.72 37.22 31.70 52.16 49.70 25.58 43.39 47.96 53.86 54.67 54.64 47.78 63.10 66.06

53.06 63.08 25.56 43.19 38.69 44.43 44.98 57.57 47.02 63.54 38.13 39.16 45.87 54.68 51.81 59.44 48.58 57.80 64.13

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

71.07 79.73 55.01 54.79 59.68 62.74 57.00 67.19 55.68 76.48 41.11 56.82 49.99 65.00 57.93 64.69 45.52 59.26 62.00

*Participants who had a disagreement between perceptual ratings and nasometry scores.

Test sensitivity, specificity, and overall efficiency results are presented in tables 5–8. Results indicated good relationships between perceptual judgements of hypernasality and nasalance scores for the total test sentences (cut-off535%, sensitivity50.83, specificity50.78, overall efficiency50.82), high-pressure consonant sentences (cutoff524%, sensitivity50.83, specificity50.86, overall efficiency50.84) and lowpressure consonant sentences (cut-off528%, sensitivity50.88, specificity50.78, overall efficiency50.86). There was a good relationship between perceptual judgements of hyponasality and nasalance scores for the nasal sentence (cutoff536%, sensitivity50.71, specificity50.95, overall efficiency50.92). Discussion This paper presents part of a larger study undertaken by the first author that aimed to evaluate the relationship between perceptual and instrumental assessment of Table 4. Pearson correlation coefficients for the relationship between perceptual ratings of hypernasality and mean nasalance scores for each sentence category, and the relationship between perceptual ratings of hyponasality and mean nasalance scores for the nasal sentence category (n550)

Correlation Coefficient

Total sentences

High-pressure consonant sentences

Low-pressure consonant sentences

Nasal consonant sentence

0.74 p,0.001

0.74 p,0.001

0.69 p,0.001

20.76 p,0.001

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Table 5. Extent to which nasalance scores obtained during the production of the total test sentences identified the presence or absence of hypernasality Hypernasality Nasalance

Present

Absent

#35 .35

6 30

11 3

Total

36

14

Total 17 33

Sensitivity

Specificity

Overall efficiency

0.83

0.78

0.82

Table 6. Extent to which nasalance scores obtained during the production of high-pressure consonant sentences identified the presence or absence of hypernasality Hypernasality Nasalance

Present

Absent

#24 .24

6 30

12 2

Total

36

14

Total 18 32

Sensitivity

Specificity

Overall efficiency

0.83

0.86

0.84

Table 7. Extent to which nasalance scores obtained during the production of low-pressure consonant sentences identified the presence or absence of hypernasality Hypernasality Nasalance

Present

Absent

#28 .28

4 32

11 3

Total

36

14

Table 8.

Total 15 35

Sensitivity

Specificity

Overall efficiency

0.88

0.78

0.86

Extent to which nasalance scores obtained during the production of a nasal sentence identified the presence or absence of hyponasality Hyponasality

Nasalance

Present

Absent

>37 ,37

2 5

41 2

Total

7

43

Total 43 7

Sensitivity

Specificity

Overall efficiency

0.71

0.95

0.92

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nasality (hyper- and hyponasality) and nasal airflow errors (nasal emission, nasal turbulence, and nasal fricative/velopharyngeal fricative substitutions) (Sweeney 2000). It focuses on the nasality aspects of the larger study using a descriptive scale for the assessment of nasality, which addressed some of the limitations of previous perceptual assessments. In particular, the terms used to describe nasality were defined, and the severity levels of scales were described in terms of what the listener perceives. Some of the definitions and descriptive scales have been subsequently adopted for use in other approaches to assessment of cleft speech (John et al. 2006). This is the first study to report a strong relationship between perceptual ratings of nasality and nasalance scores for speech stimuli containing all consonant types (r50.74, p,0.001; sensitivity50.83, specificity50.78, overall efficiency50.82). This improvement in relationship compared with previous studies may result from methodological differences between the studies (Paynter et al. 1991, Dalston and Seaver 1992, Keuning et al. 2002). Firstly, different speech stimuli had been used for the perceptual and nasometric assessments in previous studies. In the present study the speech sample used for nasometric assessment formed part of the speech sample used for perceptual assessment. Secondly, a panel of judges rated the speech stimuli from audio recordings in Paynter et al. (1991). Watterson et al. (1998b) reported that when panels of listeners are used to obtain nasality ratings, important individual variability of ratings is lost, resulting in weak correlations between perceptual ratings of nasality and nasalance scores. In the present study, one expert listener with established reliability rated speech in a live situation and these ratings were used to determine the relationship between assessment results. The live assessment ensured there was no loss of visual information associated with cleft speech errors nor any loss of sound quality associated with recorded speech samples. Finally, in Keuning et al. (2002) the listeners rated hypernasality, nasal emission, misarticulations and intelligibility. This multi-tasking may have adversely influenced listeners’ perceptual ratings of each speech parameter. In the present study the listener rated nasality and nasal airflow errors only, thus possibly providing a more valid and reliable perceptual assessment. Importantly and contrary to previous studies, the present findings indicate that nasometry scores for a speech sample containing all consonant types related well to the detailed perceptual nasality scale. This speech sample may have greater face validity as it represents the content of spontaneous speech. The relationship between nasalance scores for high-pressure consonant sentences and hypernasality in the present study was similar to relationships reported in previous studies (r50.74, sensitivity50.83, specificity50.86, overall efficiency50.84) (Paynter et al. 1991, Watterson et al. 1998a). The present study supports the view that nasalance scores for a passage devoid of nasal consonants are a good predictor of velopharyngeal dysfunction (Dalston et al. 1991a, Watterson et al. 1996). However, the relationship between the nasalance scores for low-pressure consonant sentences and perceptual ratings of nasality in the present study (r50.69, sensitivity50.88, specificity50.78, overall efficiency50.86) was weaker than the relationship reported by Watterson et al. (1998a) (r50.77). In Watterson et al. (1998a), perceptual ratings of hypernasality were made on sentences containing lowpressure consonants only (devoid of high-pressure or nasal consonants). The same sentences were used to obtain nasalance scores for low-pressure sentences. The use of the identical speech sample for both measurements may have resulted in the stronger relationship between measurements in the Watterson et al. study. Further


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investigation is required to compare perceptual ratings of nasality for each sentence category using this profile with nasalance scores for each category. A good relationship was found between nasalance scores during the production of the nasal sentence and perceptual ratings of hyponasality (r520.76; test sensitivity50.71; test specificity50.95 and an overall efficiency50.92). Dalston et al. (1991b) reported a sensitivity of 1.0, a specificity of 0.85, and an overall efficiency of 0.90 in subjects without audible nasal emission. Hardin et al. (1992) reported similar findings for a similar population. Participants in the present study who were hyponasal had no audible nasal emission and would therefore be similar to the groups studied by Dalston et al. (1991b) and Hardin et al. (1992). However, compared with similar populations, sensitivity was lower in the present study. The difference in results may be due to the limited speech sample (one nasal sentence) used in the present study for obtaining the nasalance score. The present results indicate that high nasalance scores did not always reflect a high perceptual rating of hypernasality. Watterson et al. (1993) stated that a lack of agreement between the Nasometer and perceptual ratings might be partly due to the Nasometer’s limited measurements of hypernasality, relative to the information that may be used by the rater. They pointed out that the Nasometer uses a 300-Hz bandpass filter centred at this frequency range, although the acoustic effects of nasalization are not restricted to 500 Hz. This supports the need to supplement perceptual judgements using nasometry but not to replace them, as nasometry is assessing different aspects of speech. Twelve participants (25%) in the study cohort were identified as having disagreement between the perceptual and nasometric measurements (table 3), where nasalance scores for any of the sentence categories did not agree with perceptual ratings using the cut-off values identified in tables 5–8. All of these 12 participants had perceived nasal airflow errors. Inconsistent nasality was evident in nine of these 12 participants. It is likely that the degree and indeed consistency of nasality varied between the nasometric test and the perceptual assessment in the present study, as the two evaluations were undertaken consecutively and not simultaneously. In this study 14 children had associated articulatory errors as classified according to the GOS.SP.ASS ’98 (Sell et al. 1999). However, of the 12 participants in which there was a disagreement between the perceptual and nasometric measurements, only one presented with articulatory errors. Hence, articulatory errors did not appear to influence the overall agreement between perceptual and nasometric results. This suggests that the presence of associated nasal airflow errors, the more minor degrees of hypernasality, the consistency of hypernasality, as well the acoustic restrictions of the Nasometer may influence the relationship between perceptual and nasometric measurements. It is also important to remember that other factors may also influence perceptual assessment, including listeners’ experience, listening conditions and there may be others as yet unknown (John et al. 2006). Some limitations of the present study are apparent. The speech samples for the two assessment procedures differed slightly as perceptual ratings of the full speech sample were compared with nasometry scores of sentences only. Previous studies have highlighted the need for a detailed speech sample in perceptual assessment of nasality (Shprintzen 1996). Although the speech samples for each assessment differed, significant consideration was given in devising a speech sample for nasometry that compared well with the perceptual speech sample in terms of consonant type and percentage of nasal consonants. Only one nasal sentence was used in the speech stimulus

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for investigation of hyponasality. This was to ensure that the total test sentences had 11% nasal consonants, which is representative of the percentage of nasal consonants in normal speech (Fletcher et al. 1989). Although the present study found a good relationship between perceptual ratings of hyponasality and nasalance scores for the nasal sentence, the nasalance scores may not be reliable for assessment of individuals. This weak reliability was noted in the test–retest analysis of the nasal sentence. It is recommended that a separate speech stimulus be used to assess hyponasality. Further research is in progress looking at a nasal speech sample for Irish children. This study found a strong relationship between perceptual ratings of nasality and nasalance scores for controlled speech samples, which may be due to the nature of the scale as well as the use of controlled speech samples for each assessment procedure. Hence, the use of the descriptive scale and nasometry provide a clinical protocol for evaluating speech of individuals with velopharyngeal dysfunction. Conclusions The results of this study indicated a strong relationship between detailed perceptual ratings of hypernasality and nasalance scores for controlled speech samples. Thus, a protocol for assessment of hypernasality, which includes detailed perceptual ratings and nasalance scores for the total test sentences and the high-pressure consonant sentences has good validity for the clinical assessment of hypernasality. Further investigation is required to evaluate the usefulness of the Temple Street Scale for assessing hyponasality with a more detailed nasal speech sample. The results of this study provide further evidence for the need to use the Nasometer to supplement but never replace the perceptual assessment. This study indicates that when there is agreement between perceptual and nasometric measurements, one can have confidence in the clinical findings. Such a protocol should inform management and/or intervention when assessing children with hypernasality. The protocol provides additional information, which is quantitative and qualitative and could facilitate sharing of information with other team members. Acknowledgements The Child Health Foundation, The Children’s University Hospital, Temple Street, Dublin, funded this project. The authors wish to thank Mr Fran Hegarty, Senior Physicist, St James’s Hospital Dublin, for his technical contribution in setting up and testing the instrumentation used in this study, and Professor Pam Grunwell for her advice in setting up this research. Special thanks also to Eilis Murphy and Mary Pat O’Malley, speech and language therapists, for their assistance in the reliability study. Portions of this paper were presented at the 6th European Craniofacial Congress, Manchester, UK, June 1999, and at the American Cleft Palate-Craniofacial Association Annual Meeting; Atlanta, GA, USA, April 2000. References DALSTON, R. M. and SEAVER, E. J., 1992, Relative values of various standardised passages in the nasometric assessment of patients with velopharyngeal impairment. Cleft Palate Craniofacial Journal, 29, 17–21.


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DALSTON, R. M., WARREN, D. and DALSTON, E., 1991a, Use of nasometry as a diagnostic tool for identifying patients with velopharyngeal impairment. Cleft Palate Craniofacial Journal, 28, 184–188. DALSTON, R. M., WARREN, D. and DALSTON, E., 1991b, A preliminary investigation concerning use of nasometry in identifying patients with hyponasality and/or nasal airway impairment. Journal of Speech and Hearing Research, 34, 11–18. FLETCHER, S. G., 1978, In Diagnosing Speech Disorders from Cleft Palate (New York, NY: Grune & Statton), pp. 92–157. FLETCHER, S. G., ADAMS, L. E. and MCCUTCHEON, M. J., 1989, Cleft palate speech assessment through oral– nasal acoustic measures. In K. R. Bzoch (ed.), Communicative Disorders Related to Cleft Lip and Palate (Boston, MA: Little-Brown), pp. 246–257. GRUNWELL, P. and HARDING, A., 1995, PACSTOYS: A Screening Assessment of Phonological Development (Windsor: NFER-Nelson). GRUNWELL, P., SELL, D. and HARDING, A., 1993, Describing cleft palate speech. In P. Grunwell (ed.), Analysing Cleft Palate Speech (London: Whurr), pp. 6–18. HARDIN, M. A., VAN DEMARK, D. R., MORRIS, H. L. and PAYNE, M. M., 1992, Correspondence between nasalance scores and listener judgements of hypernasality and hyponasality. Cleft Palate– Craniofacial Journal, 29, 346–351. HAYDEN, C. and KLIMACKA, L., 2000, Inter-rater reliability in cleft palate speech assessment. Journal of Clinical Excellence, 2, 269–173. HUTTERS, B. and HENNINGSSON, G., 2004, Speech outcome following treatment in cross-linguistic cleft palate studies: methodological implications. Cleft Palate–Craniofacial Journal, 41, 544–549. JOHN, A., SELL, D., SWEENEY, T., HARDING-BELL, A. and WILLIAMS, A., 2006, The cleft audit protocol for speech-augmented: a validated and reliable measure for auditing cleft speech. Cleft Palate– Craniofacial Journal, 43, 272–288. KARNELL, M. P., 1995, Discrimination of hypernasality and turbulent nasal airflow. Cleft Palate– Craniofacial Journal, 32, 145–148. KENT, R. D., 1996, Hearing and believing: some limits to the auditory–perceptual assessment of speech and voice disorders. American Journal of Speech–Language Pathology, 5, 7–23. KEUNING, K., WIENEKE, G., VAN WIJNGAARDEN, H. and DEJONCKERE, P., 2002, The correlation between nasalance and a differential perceptual rating of speech of Dutch patients with velopharyngeal insufficiency. Cleft Palate–Craniofacial Journal, 39, 277–284. KUEHN, D. P., 1982, Assessment of resonance disorders. In N. J. Lass, L. V. McReynolds, J. C. Northern and D. E. Yoder (eds), Speech, Language and Hearing, Vol. II: Pathologies of Speech and Language (Philadelphia, PA: W. B. Saunders), pp. 158. KUEHN, D. and MOLLER, K. T., 2000, Speech and language issues in the cleft palate population: the state of the art. Cleft Palate–Craniofacial Journal, 37, 348–348. KUEHN, D. and MOON, J. B., 1998, Velopharyngeal closure force and levator palatini activation levels in varying phonetic contexts. Journal of Speech, Language and Hearing Research, 41, 51–62. MCWILLIAMS, B. J., MORRIS, H. and SHELTON, R., 1990, Cleft Palate Speech. 2nd Edn (Philadelphia, PA: BC Decker). MOON, J. B., 1993, Evaluation of velopharyngeal function. In K. T. Moller and C. D. Starr (eds), Cleft Palate: Interdisciplinary Issues and Treatment for Clinicians by Clinicians (Austin, TX: Pro-Ed), pp. 251–306. PAYNTER, E. T., WATTERSON, T. L. and BOOSE, W. T., 1991, The relationship between nasalance and listener judgements. Paper presented at the American Cleft Palate-Craniofacial Association Convention, Hilton Head, SC, USA. SEAVER, E. J., DALSTON, R. M., LEEPER, H. A. and ADAMS, L. E., 1991, A study of nasometric values for normal nasal resonance. Journal of Speech and Hearing Research, 34, 715–721. SELL, D., 2005, A review of issues in perceptual speech analysis in cleft palate and related disorders. International Journal of Language Communication Disorders, 42, 103–121. SELL, D., HARDING, A. and GRUNWELL, P., 1999, GOS.SP.ASS ’98: an assessment for speech disorders associated with cleft palate and/or velopharyngeal dysfunction (revised). International Journal of Language and Communication Disorders, 34, 17–33. STREINER, D. L. and NORMAN, G. R., 1995, Health Measurement Scales: A Practical Guide to their Development and Use (Oxford: Oxford University Press). SWEENEY, C., 2000, The perceptual and instrumental assessment of nasality and nasal airflow errors associated with velopharyngeal dysfunction. PhD thesis, Trinity College, Dublin.

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Appendix 1 Participants repeated the following syllables and words: ‘pa pa pa’63; ‘hamper, hamper, hamper’63. Participants repeated the following sentences: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

Paul likes apple pie Ben is a baby boy Tim had a tart for tea Daddy mended the door Kevin’s looking at the book Gary’s got a bag of Lego The phone fell off the shelf Vickey’s got a very heavy bag The shoe shop was shut John jumped off the bridge The children were watching a football match I saw Sam sitting on a bus The zebra lives at the zoo Mum came home early We were away all year Will you wear a lily?

Participants were asked to recite the following: Jack & Jill went up the hill, to fetch a pail of water, Jack fell down and broke his crown, and Jill came tumbling after. Participants were asked to count from one to 20 and from 60 to 70. Participants were engaged in a minimum of two minutes conversational speech

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Perceptual ratings of nasality and nasometry scores Appendix 2: Total test sentences for nasometry High-pressure consonant sentence category: 1. 2. 3. 4. 5.

Paul likes apple pie Gary’s got a bag of Lego Vickey’s got a very heavy bag The zebra lives at the zoo The shoe shop was shut

Low-pressure consonant sentence category: 6. We were away all year 7. Will you wear a lily? Mixed consonant sentences (part of total test sentence category): 8. 9. 10. 11. 12. 13. 14. 15.

Ben is a baby boy Tim had a tart for tea Daddy mended the door Kevin’s looking at the book The phone fell off the shelf I saw Sam sitting on a bus John jumped off the bridge The children were watching a football match

Nasal consonant sentence category: 16. Mum came home early Appendix 3: Temple Street Scale of nasality and nasal airflow errors Weak/strong — intensity of audible nasal airflow on sounds. Nasality Hypernasality:

Present Absent 1) Mild, evident but acceptable. 2) Mild/moderate, unacceptable distortion , evident on high vowels. 3) Moderate, evident on high and low vowels. 4) Moderate/severe, evident on all vowels and some consonants. 4) Severe, evident on all vowels and most voiced consonants. Consistent Inconsistent

Hyponasality:

Present Absent 1) Evident, but acceptable. 2) Moderate — all vowels reduced nasality. 3) Severe — total denasal production of nasal consonants. Consistent Inconsistent

Cul-de-sac:

Present

Absent

Weak Frequent Consistent Phoneme Specific

Strong Infrequent Inconsistent

Nasal airflow Nasal emission:

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Nasal fricative:



Nasal turbulence:



Velopharyngeal fricative:

Weak

Strong

Frequent Consistent Phoneme Specific

Infrequent Inconsistent

Present

Absent

Intranasal turbulence

Consistency — same level and frequency in different speech situations. Frequency — percentage of nasal emissions in a passage. Phoneme specific — only present on certain sounds consistently. ____________________________________________________ Voice: Normal Dysphonic Reduced volume ____________________________________________________ Summary Test words Articulation ________________________________________________ Nasality _______________________________________________ Sentence repetition Articulation ____________________________________________ Nasality _______________________________________________ Automatic speech Jack/Jill _______________________________________________ Counting 1–20 _____________________60–70__________________ Conversational speech Articulation ______________________________________________ Nasality _________________________________________________