Normative data and construct validity of a cross-linguistic functional speech outcome, the Intelligibility in Context Scale: Italian (ICS–I)

International Journal of Pediatric Otorhinolaryngology 132 (2020) 109924

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Normative data and construct validity of a cross-linguistic functional speech outcome, the Intelligibility in Context Scale: Italian (ICS–I)

T

Silvia Piazzalungaa,b,∗, Nicoletta Salernib, Federico Ambrogic, Sofia Limarzid, Giulia Viscontia, Antonio Schindlera a

Department of Biomedical and Clinical Sciences “L. Sacco”, University of Milan, Milan, Italy Department of Psychology, University of Milan-Bicocca, Milan, Italy c Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy d Scientific Institute IRCCS “E. Medea”, Bosisio Parini, Italy b

ARTICLE INFO

ABSTRACT

Keywords: Intelligibility in Context Scale Norming data Functional intelligibility Speech sound disorder Speech assessment Parent report

Objectives: The Intelligibility in Context Scale (ICS) is a parent-report scale, world-wide translated and widely validated, by which parents can rate their child's functional speech intelligibility according to seven different communicative partners. The study aimed to report and discuss the normative data of the Italian version of ICS (ICS–I) in Italianspeaking preschool children, and to investigate whether the age influences the ICS-I scores (construct validity). Socio-economic status (SES) of the family were investigated and compared to parents' ratings on child's speech intelligibility. Methods: A cross-sectional observational study was conducted. Italian-speaking children aged 3–6 years (n = 355; mean age = 56.06 months; SD = 9.8 months), without major developmental impairment, were recruited in kindergartens throughout a convenience sampling. Parents completed a self-report form on their family SES (educational level and employment status of fathers and mothers). Children were independently rated by their mothers (ICS-Im) and fathers (ICS-If). Results: Results show that ICS normative data for the Italian preschool population (ICS-Im = 4.52; SD = 0.46; ICS-If = 4.47; SD = 0.49) are consistent with previous evidence found in other languages, suggesting that ICS could be a potential cross-linguistic tool to assess functional intelligibility. A statistically significant (p < 0.001) improvement in ICS-I score was found with increase of age (construct validity). No evidence of association (p > 0.05) with ICS-I was found for SES family. Conclusion: The study provides normative data of the functional intelligibility assessed by a subjective parental scale. As for other previous international studies, ICS-I normative data suggest that a preschool child without major impairment shows a high degree of speech intelligibility, even if minimal differences of intelligibility are reported for different communicative partners. The current findings support clinicians and researchers in implementing ICS-I in typical and also in atypical population with different SES background and promoting its application as a potential outcome measure in children with Speech Sound Disorders.

1. Introduction 1.1. Intelligibility in clinical practice In recent years, significant changes occurred in the attempt to define the theoretical and clinical concept of intelligibility. The dyadic and

fluid nature of intelligibility has been recently pointed up: the speaker as well the listener are crucial to make a verbal signal understood [1]. Both of them are responsible for pursuing and achieving an acceptable degree of intelligibility. Thus, the match between the intended communicative productions of the speaker and the comprehension from the listener results in a degree along with a continuum between perfect or

Corresponding author. Phoniatric Unit, Azienda Ospedaliera “Luigi Sacco” , Via G.B. Grassi 74, Milano, 20154, Italy. E-mail addresses: [email protected], [email protected] (S. Piazzalunga), [email protected] (N. Salerni), [email protected] (F. Ambrogi), [email protected] (S. Limarzi), [email protected] (G. Visconti), [email protected] (A. Schindler). ∗

https://doi.org/10.1016/j.ijporl.2020.109924 Received 7 November 2019; Received in revised form 30 January 2020; Accepted 30 January 2020 Available online 01 February 2020 0165-5876/ © 2020 Published by Elsevier B.V.

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null intelligibility. Intelligibility may depend on the competence of listeners because familiarity with the speaker, hearing acuity, and personal experience with speech detection can influence how intelligible someone's speech appears [2]. The interest level and the cognitive load of the listener during conversation are additional relevant factors [3]. Hustad [4] pointed up that children with moderate to severe Speech Sound Disorders (SSDs) can show marked unintelligibility, and their effective-functional communication and social participation can be hence influenced. In the Speech and Language Pathology (SLP) clinical practice, reduced intelligibility is usually one of the primary concern for children [5], and improving intelligibility stands one of the most popular long-term aims [6]. From a clinical perspective, the assessment of speech intelligibility can lead decisive clinical effects, such as establishing the severity of the disorder in a functional approach, determining priority for intervention, setting rehabilitative goals, evaluating whether an intervention is useful [7], and contributing as an effective functional clinical outcome [4]. From a survey on 333 SLPs working in paediatric clinics in the United States, Skahen and colleagues [8] indicated that most clinicians consider intelligibility as an essential part of an SSD assessment. Particularly, intelligibility was one of the variables most often referred to as “always” estimated, even if methods of intelligibility evaluation was not specified. Prominence and spread of intelligibility is also evident in the fact that the American Speech-Language-Hearing Association (ASHA) included intelligibility as one of the Functional Communication Measures (FCMs) for the National Outcomes Measurement System (NOMS), both in the Pre-Kindergarten version (Pre-K) [9] and in the version for Kindergarten through Grade 12 Schools (K-12) [10]. FCMs are a series of disorder-specific, 7-point rating scales that are designed to measure the change over time in an individual's functional skills. According to Mullen [11], in a dataset on more than 2,000 preschool students and 14,000 K–12 students, the FCM called “Articulation/Intelligibility” is one of the most frequently scored FCMs in Pre-K NOMS, that was independently chosen by SLPs for evaluating about 75% of students. Also in the K–12 NOMS intelligibility (independently categorized from Speech Sound Production) is a very common FCM used by SLPs: it is the fourth common FCM in Grades K-3 (used in about 20% of students), and it remains a significant evaluation in older classes (5.7% of students in Grades 4–6, and 9.0% of students in Grades 7–12). Concerning the use of intelligibility as a clinical outcome, Lousada and colleagues [6] explored the efficacy of the intervention for children with phonologically based SSD, and found that the only use of some severity measures (e.g. Percentage of Consonants Correct, henceforth PCC) does not appear enough to detect the child's speech improvement. They suggest that a combination of severity measures (PCC) and intelligibility evaluation could be used in a different period of rehabilitation, to identify intervention goals and to monitor changes (through PCC) or to establish endpoint outcome measures and the long-term goal of functional communication (with intelligibility measures). Nowadays, it appears that most SLPs assess intelligibility with the paediatric population, but procedures of assessment are often vague. Researchers and clinicians can choose various kinds of task, including word identification task or scaling procedure [12,13]. The ultimate indication from Miller [14] is for using both signal-independent and -dependent measures to complement each other in the clinical assessment of intelligibility. In fact, the former can be considered an objective measure that better inform on possible targets for intervention, while the latter can closer reflect everyday intelligibility and social-functional impact of an atypical speech.

functional intelligibility, which consists of a rating scale designed for parents. By using the ICS, parents can rate their perception of the degree to which their child's speech is intelligible to seven different communicative partners (parents, immediate family, extended family, child's friends, acquaintances, teachers, and strangers/unfamiliar people). Parents can rate the degree of estimated intelligibility in a 5-point Likert scale: 1 = never, 2 = rarely, 3 = sometimes, 4 = usually, 5 = always. To date, the ICS is a widespread parental questionnaire, with several cross-linguistic translations and adaptations [17]. Psychometric properties of the tool have been largely investigated and discussed in many languages (see McLeod et al., 2012 for English [15]; Ng, To, & McLeod, 2014 for Cantonese [16]; Neumann, Rietz, & Stenneken, 2017 for German [18], Kogovšek, Ozbič, 2013 for Slovenian [19], Phạm et al., 2017 for Vietnamese [20]; Tomić & Mildner, 2014 for Croatian [21]; Washington, McDonald, McLeod, Crowe, & Devonish, 2017 for Jamaican-Creole [22], and Hopf & McDonagh, 2017 for Fijian [2]). Furthermore, to implement the ICS as a potential clinical tool, normative data have been collected and reported for Australian-English speaking children (n = 803) aged from 4; 0 to 5; 5 (years; months) [23] and Vietnamese-speaking children (n = 181) aged from 2; 0 to 5; 11 [20]. The Italian version of the ICS (Intelligibility in Context Scale: Italian, henceforth ICS-I) has been recently validated in a sample of Italian preschool children (n = 364) [25], and results on internal consistency, test-retest reliability, criterion and construct validity have been discussed. Contrarily to previous research on the ICS, the ICS-I was independently filled in by mothers (ICS-Im) and fathers (ICS-If). The Italian validation research reported an overall excellent internal consistency for both the parents' forms (α > 0.91), a high test-retest reliability (rs > 0.77, ICC > 0.88), a moderate significant concurrent validity with the objective measure of articulatory competence (PCC, PPC) (r > 0.43, p < 0.01), a significant correlation among the seven ICS-I single item scores and the ICS-I mean score. As in some cases, a statistically significant difference was observed between Italian parents' ratings (e.g. for the item parent, extended family, and strangers, and the mean score), in Italian population normative data could be collected separately for mothers' and fathers’ rates.

1.2. The Intelligibility in Context Scale

3.2. Participants

A novel tool to assess signal-dependent intelligibility was suggested by McLeod and colleagues [15], who first elaborated in 2012 the ‘Intelligibility in Context Scale (ICS)’. The ICS is a subjective measure of

The participants were recruited from eight different Italian kindergartens located in Northern Italy. All parents of children attending the selected kindergartens (n = 602) were invited to participate. Inclusion

2. Aim The present study aimed to collect and report the normative data of the Italian version of ICS (henceforth ICS-I) in a large sample of Italianspeaking preschool children. Moreover, the study investigated the impact of age on ICS-I scores (construct validity), and it explored the relationship between the educational level of parents and their employment with their ratings on child's speech intelligibility. The present study is part of an extensive research project on ICS-I: the previous findings on the psychometric properties of ICS-I has been investigated and reported [25]. 3. Method 3.1. Ethical approval The study was developed and carried out according to the Declaration of Helsinki [26] and to the Ethical Principles of Psychologists and Code of Conduct [27]. All participating parents of children provided written informed consent. Ethical approval for this study was obtained in May 2018 from the University Hospital that was leading the research project.

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Table 1 Characteristics (age and gender) of the sample. Age group (months)

N

%

Mean (months)

SD (months)

Minimum (months)

Maximum (months)

Males (n)

Males (%)

Females (n)

Females (%)

36–41 42–47 48–53 54–59 60–65 66–71 Total

29 68 41 75 63 79 355

8.2 19.2 11.5 21.1 17.7 22.3 100

39.2 45.1 50.7 56.3 62.8 68.7 56.0

1.8 1.6 1.7 1.8 1.6 1.6 9.8

36 42 48 54 60 66 36

44 47 53 59 65 71 71

14 30 16 29 36 38 163

48.3 44.1 39.0 38.7 57.1 48.1 45.9

15 38 25 46 27 41 192

51.7 55.9 61.0 61.3 42.9 51.9 54.1

criteria were the following: child's age between 36 and 71 months, having at least one Italian-native-speaking parent, and parental consent to participate in the study. Pervasive developmental disorders, intellectual disability, hearing loss, articulatory disorder or language disorder reported by parents were exclusion criteria. Parents of 476 children gave consent (participation rate = 79.1%), but 78 children were excluded from the study for the following reasons: 33 children aged less than 3; 0 years or more than 5; 11 when their parents competed ICS; 13 children had a clinical diagnosis (3 pervasive developmental disorders, 1 hearing loss, 8 articulatory disorders and 1 language disorder); 32 children had both parents who were not-Italiannative speaking. The ICS-I was given to parents of 398 children. Among these participants, 89.2% of parents (response rate) completed the questionnaire. Thus, the total sample consisted of 355 children: 163 (45.9%) boys and 192 (54.1%) girls. For ease of presentation, the sample was divided by six-months age classes (Table 1). All children were reported to use Italian as their native language. The sample consisted of 327 monolingual subjects (92,1%), whereas 28 children were speaking other languages than Italian (English, French, Spanish, Romanian, Senegalese, Czech, Polish, Albanian, Portuguese, Russian, Philippine, Bulgarian).

child (such as the presence of a major developmental disorder as a pervasive developmental disorder, intellectual disability or hearing loss, and the presence of articulatory or language disorder) and their own educational level. Afterwards, ICS-I was delivered by hand to children's parents with an instruction sheet that briefly described how the scale was to be used and specified how to complete the form. Mothers and fathers were asked to complete the questionnaire separately. 3.5. Data analysis Statistical analyses were carried out using IBM SPSS 24.0 and R software. To test the normality of the data, numerical and graphical methods (Normal Q-Q plot) were used. To report normative data, descriptive statistics were used to describe the ICS-Im and ICS-If scores in the whole sample and each age class. To estimate the reference ranges, the developmental progression of ICS-Im and ICS-If scores as a function of age was evaluated through a regression procedure using Generalized Additive Models for location, scale and shape. A Beta inflated distribution with parameters modelled as a function of age was used. Such regression is needed as the total scores have a limited range (0–5) and can be thought of as a percentage variable taking values between 0 and 1 after dividing the total score by the maximum possible score [29]. The Beta inflated model also allows for modelling the probability of 0 and 1 values. The Beta inflated model was also used for the study of the construct validity of the test by evaluating the association of age and test scores. The R package GAMLSS [30] was used for model fitting. Moreover, the association of the mean ICS-I ratings with parents’ educational level (low, medium, and high) was studied using the Beta inflated model. The significance level was set at 0.05 across all statistical analyses.

3.3. Outcome measure 3.3.1. Intelligibility in Context Scale (ICS) In the study, the Italian version of the ICS (ICS–I) [24,25] was administered. It is a parent-report measure of the functional intelligibility of children, in which parents are asked to evaluate how well the immediate family, extended family, friends, acquaintances, teachers, and strangers/unfamiliar people understand their child using a five-point Likert scale (1 = never, 2 = rarely, 3 = sometimes, 4 = usually, 5 = always). The total score can range from 5 to 35 points. The mean ICS-I score was chosen for most of the analysis.

4. Results

3.3.2. Parents’ educational level and employment To explore the association between parents' educational level and ICS-I scores, the present study followed the procedures employed by Mozzanica et al. [28], who investigated the relationship between educational level and narrative abilities in a sample of Italian children. Children's parents were asked to indicate their educational level (highest degree acquired), and the educational level was classified depending on the number of years required to acquire a degree: low (≤8 years), medium (9–13 years), or high (≥14). Children's parents were also asked to indicated their current employment status, which was classified into three different groups: unemployed or manual workers (low level), office workers (medium level), and intellectual workers (high level).

From the 355 returned ICS-I forms, there were 352 forms completed by mothers and 350 by fathers. Parents reported no difficulty in completing the questionnaire. Overall, in the whole sample, the mean average total score was 4.52 (SD = 0.46) for ICS-Im, and 4.47 (SD = 0.49) for ICS-If. Parents' ratings of children's intelligibility differed by communicative partners (Table 2), even if differences between the partners ranged minimally, with mean scores from 4.2 (lowest value) to 4.8 (highest values). In both parents' ICS-I forms, the mean score was highest for parents themselves, followed by immediate members and teachers items. On the contrary, the items extended member and child's friend did not follow the same order in mothers' and fathers' ratings. Both parents rated their children's intelligibility as lowest when speaking with strangers, and the second-lowest when speaking to acquaintances. According to parents' reports, the most common rating and median values for almost all the communicative partners were ‘always’, except for acquaintances and strangers for whom the most common rating and median values were ‘often’.

3.4. Procedures All parents of the selected kindergartens were asked to participate in the study through an invitation letter handed. Families who gave written consent were asked to complete a short questionnaire that was created for the study, concerning some anamnestic questions on the 3

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No evidence of association with ICS was found for educational level and occupational status both for the father and for the mother.

Table 2 Parents ratings for the seven items on the ICS-I for the total sample (n = 352 for ICS-Im; n = 350 for ICS-If).

Parents - M Parents - F Immediate members Immediate members Extended members Extended members Child's friend - M Child's friend - F Acquaintances - M Acquaintances - F Teachers - M Teachers - F Strangers - M Strangers - F Mean score - M Mean score - F

-M -F M F

Mean

Median

Mode

DS

Min

Max

4.85 4.77 4.66 4.61 4.51 4.43 4.49 4.46 4.35 4.30 4.52 4.51 4.27 4.21 4.52 4.47

5 5 5 5 5 4.5 5 5 4 4 5 5 4 4 4.57 4.50

5 5 5 5 5 5 5 5 4 4 5 5 4 4 5 5

0.36 0.44 0.49 0.55 0.58 0.62 0.57 0.62 0.64 0.69 0.56 0.57 0.70 0.72 0.46 0.49

4 3 3 3 3 3 3 2 3 2 3 3 2 2 3.29 2.86

5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5

5. Discussion Parents of a large sample of preschool Italian-speaking children were asked to independently rate their child's speech intelligibility through a parent report, the Intelligibility in Context Scale: Italian. The mean score across the sample (4.52 for ICS-Im, and 4.47 for ICSIf) was similar to previous findings (Table 5), such as for German (4.4) [18], English (4.4) [23], Vietnamese (4.43) [20], Standard English in Jamaican context (4.43) [22], Jamaican-Creole (4.50) [22], Fiji English (4.4) [2], Cantonese (4.56) [15]. As for the degree of best intelligibility, the Italian results are equivalent to the English [23] and German [18] ones: people who most understand the child are parents, followed by the immediate member of the family. People who least understand the child are acquaintances and, lastly, strangers. Minimal differences between languages were found for the degree of best intelligibility in extended family members, child's friends, child's teacher. The English normative data have been collected in a large sample of children aged 4–5 years. Thus, a detailed comparison with the Italian results can be made for this age. At 48–53 months, 54–59 months, and 60–65 months, ICS mean scores found in the Italian-speaking are very similar to the ones found in the English-speaking sample. As in previous research on ICS, the subjective intelligibility reported in ICS-I was related with age, and a slow and progressive increase in intelligibility is expected in the preschool age, with a high percentage of children achieving complete functional intelligibility within 6 years of age. The current results support the supposition that parents' subjective intelligibility could be considered as a potential cross-cultural and cross-linguistic measure of how a preschool child is understood in his/her linguistic environment. Thus, findings from several cross-cultural and cross-linguistic adaptations and validations of ICS allow clinicians to the benefit of an almost-universal measure to assess the functional intelligibility of a child. Results from different studies suggest that in the preschool population, a very high degree of functional intelligibility is expected: typically, a child's speech is “often” or “always” understood. For this reason, a low level of intelligibility reported by parents could be considered as a potential sign of an atypical speech or language development, thus suggesting further evaluation of the child's competences. Nevertheless, the sample of the study might not be fully representative of the Italian pre-schoolers population. For instance, children with some frequent characteristics were excluded, as children having both parents who were not Italian speaking. Furthermore, among the children whose parents gave consent to participate, we found a percentage of articulatory/language disorders much lower than the expected percentage in preschool age. Likely, our sample may include children with a speech/language impairment that was not reported by their parents. In the present study, parents' educational level and parents' current employment were chosen as proxies of SES level. As reported in Mozzanica et al. [28], also in the present Italian sample, education level and employment level were observed to be slightly higher in mothers than in fathers. The SES characteristics of the participants support the

M = mothers' ratings. F = fathers' rating. DS = standard deviation. Min = minimum value. Max = maximum value.

4.1. Normative data Normative data have been collected and reported in terms of mean, standard deviation, and percentile scores for ICS-Im (Table 3) and ICS-If (Table 4) mean score. Overall, in both parents' reports, the median value seeks to increase with age: children are ‘usually’ to ‘always’ intelligible when talking to other communicative partners. For the median value, a ceiling effect is observed in the older children (66–71 months old) according to mothers' ratings. Children with lowest scores (5° percentile) were rated as ‘sometimes’ (score equal to 3) to ‘usually’ (score equal to 4) understood, and their overall means of ICS-Im and ICS –If did not fell at ‘rarely’ (score equal to 2) or ‘never’ rating (score equal to 1). 4.2. Construct validity According to the Beta inflated model, age was significantly associated with the ICS mean score of both parents (p < 0.001 for both). The association was positive with approximately a 0.05 increase per month (Fig. 1). 4.3. Relationship between ICS and parents’ educational level The educational level of mothers resulted low in 11.9% of the sample, medium in 46.0%, high in 42.0%. The educational level of fathers was low for 17.5%, medium for 55.4%, and high for 27.1% of fathers. Mothers' employment was classified as low in 29.3%, medium in 53,4%, and high in 17,2%. Fathers’ employment was classified as low in 44.9%, medium in 43,2%, and high in 11,9%. Table 3 Normative data for ICS-Im mean scores. Age (months)

36–41 42–47 48–53 54–59 60–65 66–71

N

29 67 41 74 62 79

Mean

4.26 4.30 4.49 4.53 4.64 4.72

SD

0.45 0.47 0.50 0.45 0.40 0.38

Percentiles ICS-Im 5°

10°

15°

25°

50°

75°

90°

95°

3.50 3.43 3.57 3.86 4.00 3.86

3.71 3.57 3.77 3.93 4.00 4.14

3.86 3.71 4.00 4.00 4.06 4.29

4.00 4.00 4.00 4.14 4.29 4.43

4.14 4.29 4.57 4.43 4.79 5.00

4.57 4.57 5.00 5.00 5.00 5.00

5.00 5.00 5.00 5.00 5.00 5.00

5.00 5.00 5.00 5.00 5.00 5.00

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Table 4 Normative data for ICS-If mean scores. Age (months)

36–41 42–47 48–53 54–59 60–65 66–71

N

28 67 41 75 62 77

Mean

4.14 4.25 4.53 4.51 4.53 4.67

SD

0.47 0.58 0.46 0.49 0.42 0.37

Percentiles ICS-If 5°

10°

15°

25°

50°

75°

90°

95°

3.19 3.29 3.71 3.66 3.86 3.99

3.43 3.40 3.86 3.86 4.00 4.14

3.62 3.57 3.90 4.00 4.00 4.24

3.89 3.86 4.14 4.14 4.11 4.43

4.14 4.29 4.57 4.57 4.57 4.86

4.43 4.71 5.00 5.00 5.00 5.00

4.86 5.00 5.00 5.00 5.00 5.00

4.94 5.00 5.00 5.00 5.00 5.00

fact that the sample is adequately representative of typically Italian population. The Italian ISTAT (Istituto Nazionale di Statistica – National Institute of Statistic) indicated that the majority of Italian men are employed as manual workers, and the majority of Italian women are employed as office workers. Contrasting findings have been achieved on the relationship between SES and ICS score. As reported for Englishspeaking children [23], also in Italian-speaking children, no significant differences were found in parents' ratings on the ICS-I based on socioeconomic status. In the English study [23], the socio-economic status (ranging from most disadvantaged to most advantaged) was determined using a conventional Australian index based on geographical location. The German investigation [18] found a significant but low impact of a family's social class on ICS-G scores. In fact, a low impact of family social class (as measured by the Winkler Social Class index) was found for the father on the total average score of the ICS-G. Neumann et al. [18] suggested that ‘the German findings on sociodemographic influence have to be taken into account when assessing and comparing real-life intelligibility of children from different socio-economic background’. In the

study on Vietnamese-speaking children [20], there were significant differences between the children's ICS-VN mean score and the parents' occupation for mothers and fathers, and significant differences between children's ICS-VN mean score and the educational level of mothers but not fathers: the higher the parents' skill level and higher the mothers' educational level, the better their children's intelligibility ratings. The Italian findings, according to the results for English-speaking children, do not support an evident connection between family SES and parents' ratings of their child's speech in ICS-I. Therefore, ICS-I seems applicable for children with different SES background, and influence from parents' level education or parents' employment is not expected. 6. Conclusions The study reports and discusses normative data for ICS-I, a tool that is currently widespread all over the world. Researchers and clinicians working with Italian pre-school children can benefit from the use of a validated measure [25] whose score can be easily compared between

Fig. 1. Construct validity of ICS-I: the association between age and ICS-I scores 5

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Table 5 ICS mean score in different languages. Languages

Age range

Mean of age (SD)

N

Males (%)

Females (%)

ICS mean score (SD)

Reference

Australian-English German Vietnamese Jamaicane-Creole Fijian Cantonese Italian

48–65 months 3.0–5.92 years 24–71 months 3; 7–6; 3 (years; months) 5; 3–10; 5 (years; months) 36–72 months 36-71 moths

53.7 (3.9) months 4.18 (0.79) years 49.9 (12.7) months / / / 56.02 (9.8)

803 181 181 98 65 33 355

419 (52.1) 90 (49.7) 89 (49.2) 39 (39.8) 26 (40) / 163 (45.9)

384 (47.9) 91 (50.3%) 92 (50.8) 59 (60.2) 39 (60) / 192 (54.1)

4.4 (0.7) 4.40 (0.76) 4.43 (0.62) 4.50 (0.57) 4.6 (0.6) 4.56 (0.48) ICS-Im 4.52 (0.46); ICS-If 4.47 (0.49)

[24] [19] [21] [23] [2] [28] [25]

languages. For the Italian scientific community, having normative data on the speech intelligibility of Italian-speaking preschool children allows determine if a child differs from the expected speech competence compared to peers. For the international scientific community, the current findings highlight the possibility to develop, translate, and validate in the speech and language field, tools that overstep the potential cultural and linguistic barriers, by a functional perspective of individual functioning. By using ICS, further clinical studies in Italian or other languages could deepen the construct of functional intelligibility also in population with atypical speech development, such as children with Speech Sound Disorders, Language Disorders, disfluencies, cleft lip and cleft palate. Besides, cross-linguistic researches could verify if ICS can be a useful measure to assess bilingual children with typical or atypical speech development.

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Declaration of competing interest None. Acknowledgements The authors thank the families, children and preschool teachers who participated in this project. They extend special acknowledgement to graduate students (Selene Bertovani, Selene Fassina, Sabrina Gianera, Sara Grassi, Benedetta Ticcozzelli) for support in data collection, to Francesca Todaro for help with data analysis, and to Nicole Pizzorni for support with the ethical approval of the study. References [1] K.C. Hustad, Variability and diagnostic accuracy of speech intelligibility scores in children katherine, J. Speech, Lang. Hear. Res. 58 (2015) 1, https://doi.org/10. 1044/2015. [2] S.C. Hopf, S.H. McDonagh, Validation of the Intelligibility in Context Scale for school students in Fiji, Clin. Linguist. Phon. (2017). [3] S.L. Mattys, M.H. Davis, A.R. Bradlow, S.K. Scott, Speech recognition in adverse conditions: a review, Lang. Cognit. Process. 27 (2012) 953–978, https://doi.org/10. 1080/01690965.2012.705006. [4] K.C. Hustad, Speech intelligibility in children with speech disorders, Perspect. Lang. Learn. Educ. 19 (2012) 7, https://doi.org/10.1044/lle19.1.7. [5] A.D. Weston, L.D. Shriberg, Contextual and linguistic correlates of intelligibility in children with developmental phonological disorders, J. Speech Lang. Hear. Res. 35 (1992) 1316–1332, https://doi.org/10.1044/jshr.3506.1316. [6] M. Lousada, L.M.T. Jesus, A. Hall, V. Joffe, Intelligibility as a clinical outcome measure following intervention with children with phonologically based speechsound disorders, Int. J. Lang. Commun. Disord 49 (2014) 584–601, https://doi.org/ 10.1111/1460-6984.12095. [7] M. Gordon-Brannan, B.W. Hodson, Intelligibility/severity measurements of prekindergarten children's speech, Am. J. Speech Lang. Pathol 9 (2000) 141–150, https://doi.org/10.1044/1058-0360.0902.141. [8] S.M. Skahan, M. Watson, G.L. Lof, Speech-Language pathologists' assessment practices for children with suspected speech sound disorders: results of a national survey, Am. J. Speech Lang. Pathol 16 (2007) 246, https://doi.org/10.1044/1058-

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