Acta Oto-Laryngologica. 2014; 134: 66–72
ORIGINAL ARTICLE
Psychometric properties of the Standard-Chinese lexical neighborhood test
SUJU WANG*1,2, SHA LIU1,2, YING KONG*1,2, HAIHONG LIU1,2, JIEFEN FENG1,2, SHUJING LI1,2 & YILIN YANG1,2 1
Department of Otolaryngology - Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University and Beijing Institute of Otolaryngology, Key Laboratory of Otolaryngology - Head and Neck Surgery (Ministry of Education), Beijing, China
2
Abstract Conclusion: The psychometric characteristics of Standard-Chinese lexical neighborhood test (LNT) confirmed the lexical effects of the four word categories. The established normative baseline can be used in evaluating the word-recognition performance of the hearing-impaired listeners. Objectives: The purpose of the present study was to examine the psychometric characteristics and evaluate the reliability of Standard-Chinese LNT in children and adults. Methods: Twenty-six normalhearing adults and 13 normal-hearing children were recruited. Word recognition was tested with the Standard-Chinese LNT materials that consisted of four types of word list: monosyllable easy words, monosyllable hard words, disyllable easy words, and disyllable hard words. Results: The thresholds at 50% correct performance for the easy word lists and disyllable word lists were lower than those for the hard word lists and monosyllable word lists, respectively (all p < 0.001). The slopes for disyllable words were steeper than the monosyllable words (p < 0.05). In addition, the recognition threshold of the four categories for children was higher than that for adults (all p < 0.05). The critical difference was on average 26.6% for adults and 30.0% for children.
Keywords: Psychometric function, reliability, critical difference, Mandarin Chinese, speech recognition test
Introduction Various speech recognition tests have been developed as tools to evaluate the effects of hearing aids and cochlear implants on speech development in pediatric users. An ideal speech recognition test material should be reliable, highly sensitive to differences in test conditions, and correlate well with speech perception abilities in the real world. Several criteria have been considered essential in the selection of test items for measuring spoken word recognition by listeners with hearing impairment, including word familiarity, homogeneity, and phonetic balance [1,2]. Subsequent research [3] has indicated that speech discrimination scores for normal-hearing listeners or patients with sensorineural hearing loss do not seem to be
influenced by whether a word list is phonetically balanced or not. If we excessively emphasize phonetic balance, the choice of familiar words for young deaf children will be limited. On the other hand, if unfamiliar words are used, it is likely that we will underestimate the speech ability of the children. To overcome the limitation of phonetically balanced words for children, Kirk et al. [4] developed the lexical neighborhood test (LNT) and the multisyllabic lexical neighborhood test (MLNT). The design of the LNT and MLNT was based on the theory of the neighborhood activation model (NAM) [5] and was not phonetically balanced. In the NAM, a word stimulus input activates a set of similar acoustic-phonetic representation in memory. The process of selecting lexical words from a large number of potential candidates is
Correspondence: Sha Liu, MD, Beijing Institute of Otolaryngology, Beijing Tongren Hospital, 1 Dongjiaomin Xiang, Beijing 100730, PR China. Tel: +86 10 5826 5822. E-mail: [email protected] *These authors contributed equally to this work.
(Received 29 June 2013; accepted 23 August 2013) ISSN 0001-6489 print/ISSN 1651-2251 online 2014 Informa Healthcare DOI: 10.3109/00016489.2013.840923
Psychometric properties of the Standard-Chinese LNT dependent on the density of the neighbors and frequency of the words. All words used in this material were selected from productions by English-speaking children between the ages of 3 and 5 years and all familiar to young children. Through administering LNT and MLNT to children with cochlear implants, researchers found that the percentage of English words correctly identified was significantly higher for lexical easy words (i.e. high frequency words with few neighbors) than for hard words (i.e. low frequency words with many neighbors), and that word recognition was better for multisyllabic than for monosyllabic words [2,4]. Recently, many researchers have also developed LNT materials for their native languages [6,7]. Our laboratory established the Standard-Chinese version of the LNT [8] according to the same principles established by Pisoni and colleagues [4,5]. We have found that this test material has high inter-list equivalent and inter-rater reliability in both Mandarin Chinesespeaking normal-hearing and hearing-impaired children [8,9]. We have also demonstrated that the performance of Chinese word recognition was influenced by word frequency, neighborhood density, and age or hearing age. The results were consistent with those for other languages [4,6,7], confirming the validity of the Standard-Chinese LNT. However, the psychometric characteristics of the test need to be established. Each speech material has a special psychometric function itself. The properties of psychometric function can be used to describe the reliability and sensitivity of speech materials. Psychometric function of word recognition reflects the ability of a listener to understand a given set of speech materials as a function of the presentation level or the signal-to-noise ratio. The former function is also called the P-I function (i.e. performance-intensity function) and is the focus of the present study. There are two properties of the psychometric function, which are the speech reception threshold of 50% correct performance (i.e. SRT50) and the slope of the function. These two properties can be used to measure the homogeneity of different words or that of different word lists. Wilson and Carter [10] suggested that there are direct relationships between the variability of the test items and the thresholds and slopes of the mean psychometric function. The more homogeneous test materials showed a steeper slope of the mean psychometric function. Therefore, many researchers have used the psychometric function of each selected word to determine homogeneity of the items. Items with slopes that are different from the majority of the items are removed from the word list to increase the homogeneity of the list [11,12]. The properties of psychometric function have not been studied with either English or Chinese versions
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of the LNT. The purpose of the present study was to examine the properties of the psychometric function (i.e. the P-I function) and to compare those properties obtained from normal-hearing adult and pediatric listeners. Material and methods Subjects Two groups of normal-hearing, native Mandarin Chinese-speaking subjects were recruited from the Beijing area to participate in the present study. They were 26 adults (15 females and 11 males) and 13 typical-developing children (4 boys and 9 girls). The mean age of the adult group was 22.9 years (SD = 1.8). The age of the pediataric group ranged from 6.2 to 7.7 years with a mean of 6.9 years. All subjects were tested with pure-tone audiometry. The pure-tone air-conduction threshold was £20 dB HL at all octave frequencies between 500 and 4000 Hz. The tympanometry and acoustic reflex were all normal in all ears to be tested. None of the children reported a history of speech or hearing disorders. The use of human subjects in the present study was reviewed and approved by the institutional Review Board of Beijing Tongren Hospital. Speech materials The Standard-Chinese LNT [8,9] was used to assess open-set spoken-word recognition performance. In brief, the test materials were recorded digitally using a male talker. The Standard-Chinese LNT contains both monosyllabic and disyllabic word tests. The Standard-Chinese Monosyllabic LNT contains 3 easy-word lists and 3 hard-word lists, each with 20 words in a list, and 1 practice list that contains 10 words. The Standard-Chinese Disyllabic LNT also contains 3 easy-word lists and 3 hard-word lists each with 20 words in a list, and 1 practice list that contains 10 words. Thus, besides the two practice lists, there are four categories of word lists in the Standard-Chinese LNT, i.e. monosyllabic easy (M-E), monosyllable hard (M-H), disyllable easy (D-E), and disyllable hard (D-H) word lists. Tables I and II list all the word lists in the Standard-Chinese LNT. Design and procedure The open-set word-recognition test was conducted in a double-walled sound chamber located at the Beijing Institute of Otorhinolaryngology. The speech signals were presented monaurally through a TDH-50 headphone. The choice of test ear was randomly assigned
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Table I. Word lists of the monosyllabic words for the Standard-Chinese version of the lexical neighborhood test (LNT). Practice list
bái
Easy List 1
List 2
b o
bié
Hard List 3
List 1
biao
List 2
List 3
yang
zhí
b u
chí
ch un
cai
can
bá
beng
chán
dòng
cuì
chéng
chén
cán
càn
chí
fàng
duan
fa
dèng
ch u
cheng
d u
hán
fen
gao
hu o
da
dàng
f u
líng
gua
g un
ji u
fán
mì
gao
mén
hé
hòu
láo
hán
hè
làn
shè
jù
jie
lóu
la
lài
lìng
tiào
kai
ke
mó
làng
liàn
mı
yın
lái
liáng
pèng
zú
mán
n u
mìng
mei
qi u
nì
qiàn
páng
niú
qıng
rèn
pài
pàn
pıng
quán
ràng
shèng
pı
pı
zhàng
shòu
shuı
suì
p u
p u
rù
s ong
suan
tıng
rào
r u
shè
tián
wén
wei
shang
shào
tán
wang
x u
xi u
tà
tan
tì
yuàn
yáng
yáo
tàn
tào
wang
zheng
zhen
zhu o
t u
wa
xian
zu o
zuı
Z ou
xián
xìng
yìng
when the hearing thresholds of the two ears were equal. Otherwise, a better ear was selected to be tested based on the pure-tone average thresholds between 500 and 4000 Hz. Before data collection, the sound card outputs to an audiometer (GSI-61) were calibrated using a 1 kHz calibration tone. In a pilot study, for each category of word lists, we determined six stimulus intensities to cover the range of approximately 20–80% correct of word recognition scores so that a P-I function could be plotted. The six intensity levels were varied from 16 to 49 dB SPL for the adult subjects and from 21 to 56 dB SPL for the pediatric subjects. The six intensities produced roughly evenly spaced word recognition performance for each category of word lists. Before the real test, each subject were familiarized with the test with two practice lists, one for monosyllables and one for disyllables. During the test, each subject was tested with three of the six intensities due to constraints of time and attention span. For the adult group, half of them were randomly selected to be tested with intensities 1, 3, and 5 and the other half were tested with intensities 2, 4, and 6. Seven of the 13 children were randomly selected to be tested with intensities 1, 3, and 5 and the other 6 children were
tested with intensities 2, 4, and 6. All subjects were tested with all four categories of word lists. After each speech signal presentation, the subjects were required to repeat the word that they had heard. If they were not quite sure about the answer, they were encouraged to guess. Disyllabic easy (D-E) word lists were always presented first, followed by disyllable hard (DH) word lists, monosyllable easy (M-E) word lists, and monosyllable hard (M-H) word lists. The subjects were first presented at the middle intensity, followed by the lower intensity and then the higher intensity in order to reduce learning effects. For each stimulus intensity, all three lists for each category were tested in a random order. The entire test time for each subject was approximately 1.25 h including brief breaks during the test. Results A logistic regression [11] was used to fit the psychometric function and to calculate speech recognition thresholds and regression slopes at 50% and 20–80% correct recognition. Speech reception threshold, i.e. SRT50, was defined as the intensity at which 50% correct word recognition was achieved. Figure 1
Psychometric properties of the Standard-Chinese LNT
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Table II. Word lists of the disyllabic words for the Standard-Chinese version of lexical neighborhood test (LNT). Practice list
Easy List 1
List 2
Hard List 3
List 1
hai dài
bıng gan
sài pao
ma lù
píng gu o
fei jı
xı sh ou
fa xiàn
diàn nao
diàn chí
nán gua
diào yú
lóu tı
niú nai
mei tian
k ong tiáo
k ong lóng
lao yıng
jian chá
kai che
huá chuán
g ong zh u
xın k u
shu o huà
qian bı
hu o chái
sh u bao
miàn bao
List 2 xiàn dài
List 3 biàn huà
chí táng
t ong feng
fàng pào
jı zhì
sù liào
feng mì
huà bào
sh u tóu
yú kuài
dì dian
méi qì
shí táng
dà mı
shı ge
tian é
feng lì
ní táng
g u lì
qí shì
chı fàn
qıng wa
xı zao
tian qì
cháng pao
qıng xiang
xìn xı
gang qín
cai hóng
zh un bèi
xué xiào
jìn bù
zhı zh u
jìn rù
là zhú
sheng yın
cai sè
shàng kè
cí y u
chéng rèn
g ong sı
wèn tí
xiang jiao
a yí
líng shí
ye cao
dài yú
bào zhı
yı sheng
zài jiàn
zh u xí
dan xın
jié shù
ke ài
xué xí
sh u cài
kao yàn
jı dòng
c ong tóu
hú dié
huí dá
yán sè
hu o jiàn
tái qiú
kan jia
zuì hòu
pí qiú
yóu xì
tán qiú
hu o yàn
shí jì
w o niú
shí jian
ch un tian
w u shuì
shan feng
dào che
tóng xué
xie zì
chéng bao
hua sheng
chí dào
chéng fèn
guàn j un
tu o xié
shen tı
d u che
jiao bàn
sheng bìng
jıng chá
yù mı
wán jù
jı xiè
gao shan
dú zì
shuì jiào
y ong gan
zuò yè
che deng
w u ya
cháng páo
shows the P-I function of the four word categories of the Standard-Chinese LNT for both the adult and pediatric groups. Figure 2 shows the SRT50 and regression slopes of the P-I functions at 50% correct. For the adult listeners, SRT50 of D-E, D-H, M-E, and M-H word lists were 20.5, 25.0, 24.6, and 31.0 dB SPL, respectively. For children, SRT50 values in those four categories were 25.8, 31.2, 32.8, and 41.3 dB SPL, respectively. The differences between adult and pediatric groups were statistically significant (t test, all p < 0.05). To examine the lexical effects, the SRT50 data were subject to a one-way repeated-measures analysis of variance (ANOVA). Results showed that the lexical categories were a significant factor in word recognition (adults: F = 28.9, p < 0.0001; children: F = 43.2, p < 0.0001). A post hoc test indicated that there was a significant difference between all pairs of lexical categories with an exception of the D-H and M-E pair for both children and adults. Thus, the thresholds for monosyllabic words were higher than for disyllabic words, and those for hard words were higher than for easy words. These results indicate that, to achieve the same speech recognition level (i.e. 50% correct recognition), monosyllabic words
and hard words require a higher stimulus intensity level than disyllabic words and easy words, respectively. The slopes of the P-I functions of the four categories were calculated at 50% correct and 20–80% correct. Figure 2 plots the slope data at 50% correct since the slope data at 50% correct and at 20–80% correct showed similar patterns. It can be seen that the slopes were similar in both pediatric and adult groups, although the slopes for the adults appeared to be higher than for the children (Figure 1). Statistical tests confirmed that the differences between the two groups of subjects were not significantly different (t test, all p > 0.05). On the other hand, a one-way repeated-measures ANOVA indicated significant lexical effects (slope at 50%: adults: F = 15.0, p < 0.001; children: F = 36.4, p < 0.0001; slope at 20–80%: adults: F = 15.8, p < 0.001; children: F = 66.8, p < 0.0001). It can be seen in Figure 2 that the slopes of the D-E word list were steepest, followed by those of the D-H, M-E, and M-H word lists. A post hoc test showed that the slope differences between any two pairs of lexical categories in the 20–80% correct range were all significant (all p < 0.05) in children. However, for the adult data, the slope differences between all
S. Wang et al.
Word recognition (% correct)
70
100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0
0
10
20
30
40
50
60
D−E
D−H
M−E
M−H
70
80
0
10
20
30
40
50
60
70
80
Stimulus intensity (dB SPL) Figure 1. The performance-intensity function of normal-hearing listeners. The dotted lines represent data from the adult listeners and solid lines represent data from the children. The four panels show the data for the disyllable easy (D-E), disyllable hard (D-H), monosyllable easy (M-E), and monosyllable hard (M-H) lists. Each category of words is composed of three lists that are represented by green, red, and blue lines, respectively.
pairs of lexical categories were statistically significant (all p < 0.05) with an exception of the M-E and M-H categories. The individual differences in word recognition performance were larger in the pediatric group than in the adult group, as reflected in the standard deviation (SD) values. Another use of the SD values is to obtain the critical difference (CD) value. CD is defined as a random error of the differences of two test scores, which is specified by the largest and smallest test scores of the confidence interval [13,14]. It is calculated by multiplying SD by Z0.025 H2 (i.e. 2.63). Thus, the CD was used to assess the test–retest reliability [14,15]. Figure 3 shows the CD values in adults and children across all stimulus intensities. The CD values for the adults (26.6%) tended to be smaller than those of the pediatric group (30.0%). However, a two-way ANOVA revealed that there were no significant differences between the subject groups and word categories in the CD values (both p > 0.05). Discussion Since Kirk et al. [4] developed the LNT and the MLNT in English, many researchers have also developed LNT materials for their native languages in more recent years. Few papers have described the
psychometric properties of the newly developed tests. The present study examined the psychometric characteristics and evaluated the reliability of the Standard-Chinese version of the LNT. We found that the thresholds for the four categories of words (i.e. D-E, D-H, M-E, and M-H) reflected the lexical effects of the word lists (Figure 2, top panel), which are the targeted effects of the LNT that is designed based on the principle of NAM [5]. As reflected by the thresholds of both adult and pediatric listeners, the presentation level to reach 50% correct performance for the easy word lists was lower than for the hard word lists and that for the disyllable word lists was lower than for the monosyllable word lists. This is consistent with early experimental results of the effects of lexical characteristics on word recognition [4,5,8,9,16]. In both normal-hearing and hearingimpaired listeners, such lexical effects were shown as better recognition performance with easy word lists as compared with hard word lists and better recognition performance with disyllable word lists as compared with monosyllable word lists. Compared with the adults, the pediatric listeners showed a higher word recognition threshold. It is known that the auditory pathway in children does not reach maturity until adolescence [17], which suggests that the ability of speech recognition and
Psychometric properties of the Standard-Chinese LNT 50
50 Adults
Adults
Children
Children
40
30 CD (%)
SRT50 (dB SPL)
40
71
20
30
20
10 10
Slope at 50% correct (%/dB)
0 0
6 5
D−E
D−H
M−E
M−H
Figure 3. The 95% critical difference (CD) values with the disyllable easy (D-E), disyllable hard (D-H), monosyllable easy (M-E), and monosyllable hard (M-H) word lists. Black and white bars represent data from the adults and children, respectively. The error bars represent standard deviation (SD).
4 3 2 1 0
D−E
D−H
M−E
M−H
Figure 2. The speech recognition threshold (SRT50) and slopes at 50% correct with the disyllable easy (D-E), disyllable hard (D-H), monosyllable easy (M-E), and monosyllable hard (M-H) word lists. Black bars represent data from the adults and white bars represent data from the children. The error bars represent standard deviation (SD).
the ability to use contextual information as well as cognitive and sensory functions are still in development in young children. Compared with younger children, older children and adults can better utilize the sensory information and linguistic knowledge for better speech recognition [18]. In a previous study, we showed that there was clearly an effect of age in Mandarin Chinese word recognition in a group of children of aged 3–5 years [8,9]. Therefore, children required higher intensities than adults to reach the same performance in word recognition. The lexical effects were also reflected in the slope data of the psychometric functions (Figure 2, bottom panel). The slopes for disyllable words were steeper than those for the monosyllable words in both children and adult listeners. The slopes for easy words were steeper than those for hard words in pediatric listeners. These results were also consistent with those reported in a previous study, i.e. the easier the words, the steeper the psychometric slopes and the more redundant information, the steeper the psychometric slopes [16]. The values of psychometric slope data were largely in line with those reported in the literature. Dirks et al. [16] showed that the psychometric slope (between
70.7 and 29.3%) for English monosyllable easy words was 4.1% per decibel and that for hard words was 3.8% per decibel in normal-hearing adult listeners. In some other studies on Mandarin Chinese using various word lists, the reported slope values were also consistent with those reported here using the LNT word lists. Han et al. [19] tested Mandarin monosyllabic word recognition and found that the mean slopes of psychometric functions were 4.1% per decibel for normalhearing adults and 2.7% per decibel for hearingimpaired adults. The psychometric slopes of Mandarin disyllabic materials were found to be approximately 8% per decibel at 50% correct for normal-hearing adults [11]. For Cantonese, the psychometric slopes for the disyllable materials were found to be around 7.5% per decibel for normal-hearing adults [12]. The test–retest reliability of speech test materials can be assessed in several ways. Bentler [15] examined the test–retest reliability of the speech-in-noise (SIN) test using the test–retest correlation and the 95% CD values. Similarly, Wilson and McArdle [20] assessed the test–retest reliability of the words-in-noise (WIN) test using the same measures. It is difficult to compare the CD values of various studies due to the drastic differences in test materials (sentences versus words) and presentation levels. In a study with Mandarin phonetically balanced monosyllabic lists at similar presentation levels, Xi and colleagues [14] reported that the CD values were 21.2% for normal-hearing adult listeners. As shown in Figure 3, the overall CD values of the four word categories were 26.6% for adults and 30.0% for children, respectively. It appears that the CD values were greater in the present study. This may be due to the fact that the number of words in the lists of the Standard-Chinese LNT is fewer and that the
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number of subjects is smaller in the present study than in the study by Xi et al. [14].
Conclusion Our study examined the psychometric characteristics of Standard-Chinese LNT in normal-hearing children and adults. We found that adults had lower word recognition thresholds and steeper slopes than those for children. The lexical effects on speech recognition were the same for children and adults, i.e. the speech recognition was more accurate for lexical easy words than for hard words. Therefore, the test materials can be used to evaluate the word recognition performance of hearing-impaired children and adults. Furthermore, the CD values at 95% critical level can be used to assess the effectiveness of intervention or different aided conditions. Future studies are necessary to examine the psychometric properties of the Standard-Chinese LNT materials in the hearing-impaired population.
Acknowledgment The study was supported by the National Natural Science Foundation of China (81170916 and 30872859). Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
References [1] Hudgins CV, Hawkins JE, Karlin JE, Stevens SS. The development of recorded auditory tests for measuring hearing loss for speech. Laryngoscope 1947;57:57–89. [2] Kirk KI, Eisenberg LS, Martinez AS, Hay-McCutcheon M. The lexical neighborhood test: test-retest reliability and inter-list equivalency. J Am Acad Audiol 1998;10: 177–95. [3] Martin FN, Champlin CA, Perez DD. The question of phonetic balance in word recognition testing. J Am Acad Audiol 2000;11:489–93. [4] Kirk KI, Pisoni DB, Osberger MJ. Lexical effects on spoken word recognition by pediatric cochlear implant uses. Ear Hear 1995;16:470–81.
[5] Luce PA, Pisoni DB. Recognizing spoken words: the neighborhood activation model. Ear Hear 1998;19:1–36. [6] Yuen KC, Ng IH, Luk BP, Chan SK, Chan SC, Kwok IC, et al. The development of Cantonese lexical neighborhood test: a pilot study. Int J Pediatr Otorhinolaryngol 2008;72:1121–9. [7] Wang NM, Wu CM, Kirk KI. Lexical effects on spoken word recognition performance among mandarin-speaking children with normal hearing and cochlear implants. Int J Pediatr Otorhinolaryngol 2010;74:883–90. [8] Liu C, Liu S, Zhang N, Yang Y, Kong Y, Zhang L. Standard-Chinese Lexical Neighborhood Test in normalhearing young children. Int J Pediatr Otorhinolaryngol 2011;75:774–81. [9] Liu H, Liu S, Wang S, Liu C, Kong Y, Zhang N. Effects of lexical characteristics and demographics factors on Mandarin Chinese open-set word recognition in children with cochlear implants. Ear Hear 2013;34:221–8. [10] Wilson RH, Carter AS. Relation between slopes of word recognition psychometric functions and homogeneity of the stimulus materials. J Am Acad Audiol 2001;12:7–14. [11] Nissen SL, Harris RW, Jennings LJ, Eggett DL, Buck H. Psychometrically equivalent Mandarin bisyllabic speech discrimination materials spoken by male and female talkers. Int J Audiol 2005;44:379–90. [12] Nissen SL, Harris RW, Channell RW, Conklin B, Kim M, Wong L. The development of psychometrically equivalent cantonese speech audiometry materials. Int J Audiol 2011; 50:191–201. [13] Thornton AR, Raffin MJ. Speech-discrimination scores modeled as a binomial variable. J Speech Hear Res 1978; 21:507–18. [14] Xi X, Ji F, Zhao Y, Li J, Chen A, Xu J, et al. Reliability of a set of Mandarin phonemic-balanced short-item monosyllable lists with equivalency in audibility. Chinese J Otol 2008;6: 21–5. [15] Bentler RA. List equivalency and test-retest reliability of the speech in noise test. Am J Audiol 2000;9:84–100. [16] Dirks DD, Takayanagi S, Moshfegh A. Effects of lexical factors on word recognition among normal-hearing and hearing-impaired listeners. J Am Acad Audiol 2001;12: 233–44. [17] Paus T, Zijdenbos A, Worsley K, Collins D.L, Blumenthal J, Giedd JN. Structural maturation of neural pathways in children and adolescents: in vivo study. Science 1999;283: 1908–11. [18] Talarico M, Abdilla G, Aliferis M, Balazic I, Giaprakis I, Stefanakis T. Effect of age and cognition on childhood speech in noise perception abilities. Audiol Neurotol 2007; 12:13–19. [19] Han D, Wang S, Zhang H, Chen J, Mannell R, Newall P, et al. Development of mandarin monosyllabic speech test materials in China. Int J Audiol 2009;48:300–11. [20] Wilson RH, McArdle R. Intra- and inter-session test, retest reliability of the words-in-noise (WIN) test. J Am Acad Audiol 2007;18:813–25.
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ORIGINAL ARTICLE
Psychometric properties of the Standard-Chinese lexical neighborhood test
SUJU WANG*1,2, SHA LIU1,2, YING KONG*1,2, HAIHONG LIU1,2, JIEFEN FENG1,2, SHUJING LI1,2 & YILIN YANG1,2 1
Department of Otolaryngology - Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University and Beijing Institute of Otolaryngology, Key Laboratory of Otolaryngology - Head and Neck Surgery (Ministry of Education), Beijing, China
2
Abstract Conclusion: The psychometric characteristics of Standard-Chinese lexical neighborhood test (LNT) confirmed the lexical effects of the four word categories. The established normative baseline can be used in evaluating the word-recognition performance of the hearing-impaired listeners. Objectives: The purpose of the present study was to examine the psychometric characteristics and evaluate the reliability of Standard-Chinese LNT in children and adults. Methods: Twenty-six normalhearing adults and 13 normal-hearing children were recruited. Word recognition was tested with the Standard-Chinese LNT materials that consisted of four types of word list: monosyllable easy words, monosyllable hard words, disyllable easy words, and disyllable hard words. Results: The thresholds at 50% correct performance for the easy word lists and disyllable word lists were lower than those for the hard word lists and monosyllable word lists, respectively (all p < 0.001). The slopes for disyllable words were steeper than the monosyllable words (p < 0.05). In addition, the recognition threshold of the four categories for children was higher than that for adults (all p < 0.05). The critical difference was on average 26.6% for adults and 30.0% for children.
Keywords: Psychometric function, reliability, critical difference, Mandarin Chinese, speech recognition test
Introduction Various speech recognition tests have been developed as tools to evaluate the effects of hearing aids and cochlear implants on speech development in pediatric users. An ideal speech recognition test material should be reliable, highly sensitive to differences in test conditions, and correlate well with speech perception abilities in the real world. Several criteria have been considered essential in the selection of test items for measuring spoken word recognition by listeners with hearing impairment, including word familiarity, homogeneity, and phonetic balance [1,2]. Subsequent research [3] has indicated that speech discrimination scores for normal-hearing listeners or patients with sensorineural hearing loss do not seem to be
influenced by whether a word list is phonetically balanced or not. If we excessively emphasize phonetic balance, the choice of familiar words for young deaf children will be limited. On the other hand, if unfamiliar words are used, it is likely that we will underestimate the speech ability of the children. To overcome the limitation of phonetically balanced words for children, Kirk et al. [4] developed the lexical neighborhood test (LNT) and the multisyllabic lexical neighborhood test (MLNT). The design of the LNT and MLNT was based on the theory of the neighborhood activation model (NAM) [5] and was not phonetically balanced. In the NAM, a word stimulus input activates a set of similar acoustic-phonetic representation in memory. The process of selecting lexical words from a large number of potential candidates is
Correspondence: Sha Liu, MD, Beijing Institute of Otolaryngology, Beijing Tongren Hospital, 1 Dongjiaomin Xiang, Beijing 100730, PR China. Tel: +86 10 5826 5822. E-mail: [email protected] *These authors contributed equally to this work.
(Received 29 June 2013; accepted 23 August 2013) ISSN 0001-6489 print/ISSN 1651-2251 online 2014 Informa Healthcare DOI: 10.3109/00016489.2013.840923
Psychometric properties of the Standard-Chinese LNT dependent on the density of the neighbors and frequency of the words. All words used in this material were selected from productions by English-speaking children between the ages of 3 and 5 years and all familiar to young children. Through administering LNT and MLNT to children with cochlear implants, researchers found that the percentage of English words correctly identified was significantly higher for lexical easy words (i.e. high frequency words with few neighbors) than for hard words (i.e. low frequency words with many neighbors), and that word recognition was better for multisyllabic than for monosyllabic words [2,4]. Recently, many researchers have also developed LNT materials for their native languages [6,7]. Our laboratory established the Standard-Chinese version of the LNT [8] according to the same principles established by Pisoni and colleagues [4,5]. We have found that this test material has high inter-list equivalent and inter-rater reliability in both Mandarin Chinesespeaking normal-hearing and hearing-impaired children [8,9]. We have also demonstrated that the performance of Chinese word recognition was influenced by word frequency, neighborhood density, and age or hearing age. The results were consistent with those for other languages [4,6,7], confirming the validity of the Standard-Chinese LNT. However, the psychometric characteristics of the test need to be established. Each speech material has a special psychometric function itself. The properties of psychometric function can be used to describe the reliability and sensitivity of speech materials. Psychometric function of word recognition reflects the ability of a listener to understand a given set of speech materials as a function of the presentation level or the signal-to-noise ratio. The former function is also called the P-I function (i.e. performance-intensity function) and is the focus of the present study. There are two properties of the psychometric function, which are the speech reception threshold of 50% correct performance (i.e. SRT50) and the slope of the function. These two properties can be used to measure the homogeneity of different words or that of different word lists. Wilson and Carter [10] suggested that there are direct relationships between the variability of the test items and the thresholds and slopes of the mean psychometric function. The more homogeneous test materials showed a steeper slope of the mean psychometric function. Therefore, many researchers have used the psychometric function of each selected word to determine homogeneity of the items. Items with slopes that are different from the majority of the items are removed from the word list to increase the homogeneity of the list [11,12]. The properties of psychometric function have not been studied with either English or Chinese versions
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of the LNT. The purpose of the present study was to examine the properties of the psychometric function (i.e. the P-I function) and to compare those properties obtained from normal-hearing adult and pediatric listeners. Material and methods Subjects Two groups of normal-hearing, native Mandarin Chinese-speaking subjects were recruited from the Beijing area to participate in the present study. They were 26 adults (15 females and 11 males) and 13 typical-developing children (4 boys and 9 girls). The mean age of the adult group was 22.9 years (SD = 1.8). The age of the pediataric group ranged from 6.2 to 7.7 years with a mean of 6.9 years. All subjects were tested with pure-tone audiometry. The pure-tone air-conduction threshold was £20 dB HL at all octave frequencies between 500 and 4000 Hz. The tympanometry and acoustic reflex were all normal in all ears to be tested. None of the children reported a history of speech or hearing disorders. The use of human subjects in the present study was reviewed and approved by the institutional Review Board of Beijing Tongren Hospital. Speech materials The Standard-Chinese LNT [8,9] was used to assess open-set spoken-word recognition performance. In brief, the test materials were recorded digitally using a male talker. The Standard-Chinese LNT contains both monosyllabic and disyllabic word tests. The Standard-Chinese Monosyllabic LNT contains 3 easy-word lists and 3 hard-word lists, each with 20 words in a list, and 1 practice list that contains 10 words. The Standard-Chinese Disyllabic LNT also contains 3 easy-word lists and 3 hard-word lists each with 20 words in a list, and 1 practice list that contains 10 words. Thus, besides the two practice lists, there are four categories of word lists in the Standard-Chinese LNT, i.e. monosyllabic easy (M-E), monosyllable hard (M-H), disyllable easy (D-E), and disyllable hard (D-H) word lists. Tables I and II list all the word lists in the Standard-Chinese LNT. Design and procedure The open-set word-recognition test was conducted in a double-walled sound chamber located at the Beijing Institute of Otorhinolaryngology. The speech signals were presented monaurally through a TDH-50 headphone. The choice of test ear was randomly assigned
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Table I. Word lists of the monosyllabic words for the Standard-Chinese version of the lexical neighborhood test (LNT). Practice list
bái
Easy List 1
List 2
b o
bié
Hard List 3
List 1
biao
List 2
List 3
yang
zhí
b u
chí
ch un
cai
can
bá
beng
chán
dòng
cuì
chéng
chén
cán
càn
chí
fàng
duan
fa
dèng
ch u
cheng
d u
hán
fen
gao
hu o
da
dàng
f u
líng
gua
g un
ji u
fán
mì
gao
mén
hé
hòu
láo
hán
hè
làn
shè
jù
jie
lóu
la
lài
lìng
tiào
kai
ke
mó
làng
liàn
mı
yın
lái
liáng
pèng
zú
mán
n u
mìng
mei
qi u
nì
qiàn
páng
niú
qıng
rèn
pài
pàn
pıng
quán
ràng
shèng
pı
pı
zhàng
shòu
shuı
suì
p u
p u
rù
s ong
suan
tıng
rào
r u
shè
tián
wén
wei
shang
shào
tán
wang
x u
xi u
tà
tan
tì
yuàn
yáng
yáo
tàn
tào
wang
zheng
zhen
zhu o
t u
wa
xian
zu o
zuı
Z ou
xián
xìng
yìng
when the hearing thresholds of the two ears were equal. Otherwise, a better ear was selected to be tested based on the pure-tone average thresholds between 500 and 4000 Hz. Before data collection, the sound card outputs to an audiometer (GSI-61) were calibrated using a 1 kHz calibration tone. In a pilot study, for each category of word lists, we determined six stimulus intensities to cover the range of approximately 20–80% correct of word recognition scores so that a P-I function could be plotted. The six intensity levels were varied from 16 to 49 dB SPL for the adult subjects and from 21 to 56 dB SPL for the pediatric subjects. The six intensities produced roughly evenly spaced word recognition performance for each category of word lists. Before the real test, each subject were familiarized with the test with two practice lists, one for monosyllables and one for disyllables. During the test, each subject was tested with three of the six intensities due to constraints of time and attention span. For the adult group, half of them were randomly selected to be tested with intensities 1, 3, and 5 and the other half were tested with intensities 2, 4, and 6. Seven of the 13 children were randomly selected to be tested with intensities 1, 3, and 5 and the other 6 children were
tested with intensities 2, 4, and 6. All subjects were tested with all four categories of word lists. After each speech signal presentation, the subjects were required to repeat the word that they had heard. If they were not quite sure about the answer, they were encouraged to guess. Disyllabic easy (D-E) word lists were always presented first, followed by disyllable hard (DH) word lists, monosyllable easy (M-E) word lists, and monosyllable hard (M-H) word lists. The subjects were first presented at the middle intensity, followed by the lower intensity and then the higher intensity in order to reduce learning effects. For each stimulus intensity, all three lists for each category were tested in a random order. The entire test time for each subject was approximately 1.25 h including brief breaks during the test. Results A logistic regression [11] was used to fit the psychometric function and to calculate speech recognition thresholds and regression slopes at 50% and 20–80% correct recognition. Speech reception threshold, i.e. SRT50, was defined as the intensity at which 50% correct word recognition was achieved. Figure 1
Psychometric properties of the Standard-Chinese LNT
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Table II. Word lists of the disyllabic words for the Standard-Chinese version of lexical neighborhood test (LNT). Practice list
Easy List 1
List 2
Hard List 3
List 1
hai dài
bıng gan
sài pao
ma lù
píng gu o
fei jı
xı sh ou
fa xiàn
diàn nao
diàn chí
nán gua
diào yú
lóu tı
niú nai
mei tian
k ong tiáo
k ong lóng
lao yıng
jian chá
kai che
huá chuán
g ong zh u
xın k u
shu o huà
qian bı
hu o chái
sh u bao
miàn bao
List 2 xiàn dài
List 3 biàn huà
chí táng
t ong feng
fàng pào
jı zhì
sù liào
feng mì
huà bào
sh u tóu
yú kuài
dì dian
méi qì
shí táng
dà mı
shı ge
tian é
feng lì
ní táng
g u lì
qí shì
chı fàn
qıng wa
xı zao
tian qì
cháng pao
qıng xiang
xìn xı
gang qín
cai hóng
zh un bèi
xué xiào
jìn bù
zhı zh u
jìn rù
là zhú
sheng yın
cai sè
shàng kè
cí y u
chéng rèn
g ong sı
wèn tí
xiang jiao
a yí
líng shí
ye cao
dài yú
bào zhı
yı sheng
zài jiàn
zh u xí
dan xın
jié shù
ke ài
xué xí
sh u cài
kao yàn
jı dòng
c ong tóu
hú dié
huí dá
yán sè
hu o jiàn
tái qiú
kan jia
zuì hòu
pí qiú
yóu xì
tán qiú
hu o yàn
shí jì
w o niú
shí jian
ch un tian
w u shuì
shan feng
dào che
tóng xué
xie zì
chéng bao
hua sheng
chí dào
chéng fèn
guàn j un
tu o xié
shen tı
d u che
jiao bàn
sheng bìng
jıng chá
yù mı
wán jù
jı xiè
gao shan
dú zì
shuì jiào
y ong gan
zuò yè
che deng
w u ya
cháng páo
shows the P-I function of the four word categories of the Standard-Chinese LNT for both the adult and pediatric groups. Figure 2 shows the SRT50 and regression slopes of the P-I functions at 50% correct. For the adult listeners, SRT50 of D-E, D-H, M-E, and M-H word lists were 20.5, 25.0, 24.6, and 31.0 dB SPL, respectively. For children, SRT50 values in those four categories were 25.8, 31.2, 32.8, and 41.3 dB SPL, respectively. The differences between adult and pediatric groups were statistically significant (t test, all p < 0.05). To examine the lexical effects, the SRT50 data were subject to a one-way repeated-measures analysis of variance (ANOVA). Results showed that the lexical categories were a significant factor in word recognition (adults: F = 28.9, p < 0.0001; children: F = 43.2, p < 0.0001). A post hoc test indicated that there was a significant difference between all pairs of lexical categories with an exception of the D-H and M-E pair for both children and adults. Thus, the thresholds for monosyllabic words were higher than for disyllabic words, and those for hard words were higher than for easy words. These results indicate that, to achieve the same speech recognition level (i.e. 50% correct recognition), monosyllabic words
and hard words require a higher stimulus intensity level than disyllabic words and easy words, respectively. The slopes of the P-I functions of the four categories were calculated at 50% correct and 20–80% correct. Figure 2 plots the slope data at 50% correct since the slope data at 50% correct and at 20–80% correct showed similar patterns. It can be seen that the slopes were similar in both pediatric and adult groups, although the slopes for the adults appeared to be higher than for the children (Figure 1). Statistical tests confirmed that the differences between the two groups of subjects were not significantly different (t test, all p > 0.05). On the other hand, a one-way repeated-measures ANOVA indicated significant lexical effects (slope at 50%: adults: F = 15.0, p < 0.001; children: F = 36.4, p < 0.0001; slope at 20–80%: adults: F = 15.8, p < 0.001; children: F = 66.8, p < 0.0001). It can be seen in Figure 2 that the slopes of the D-E word list were steepest, followed by those of the D-H, M-E, and M-H word lists. A post hoc test showed that the slope differences between any two pairs of lexical categories in the 20–80% correct range were all significant (all p < 0.05) in children. However, for the adult data, the slope differences between all
S. Wang et al.
Word recognition (% correct)
70
100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0
0
10
20
30
40
50
60
D−E
D−H
M−E
M−H
70
80
0
10
20
30
40
50
60
70
80
Stimulus intensity (dB SPL) Figure 1. The performance-intensity function of normal-hearing listeners. The dotted lines represent data from the adult listeners and solid lines represent data from the children. The four panels show the data for the disyllable easy (D-E), disyllable hard (D-H), monosyllable easy (M-E), and monosyllable hard (M-H) lists. Each category of words is composed of three lists that are represented by green, red, and blue lines, respectively.
pairs of lexical categories were statistically significant (all p < 0.05) with an exception of the M-E and M-H categories. The individual differences in word recognition performance were larger in the pediatric group than in the adult group, as reflected in the standard deviation (SD) values. Another use of the SD values is to obtain the critical difference (CD) value. CD is defined as a random error of the differences of two test scores, which is specified by the largest and smallest test scores of the confidence interval [13,14]. It is calculated by multiplying SD by Z0.025 H2 (i.e. 2.63). Thus, the CD was used to assess the test–retest reliability [14,15]. Figure 3 shows the CD values in adults and children across all stimulus intensities. The CD values for the adults (26.6%) tended to be smaller than those of the pediatric group (30.0%). However, a two-way ANOVA revealed that there were no significant differences between the subject groups and word categories in the CD values (both p > 0.05). Discussion Since Kirk et al. [4] developed the LNT and the MLNT in English, many researchers have also developed LNT materials for their native languages in more recent years. Few papers have described the
psychometric properties of the newly developed tests. The present study examined the psychometric characteristics and evaluated the reliability of the Standard-Chinese version of the LNT. We found that the thresholds for the four categories of words (i.e. D-E, D-H, M-E, and M-H) reflected the lexical effects of the word lists (Figure 2, top panel), which are the targeted effects of the LNT that is designed based on the principle of NAM [5]. As reflected by the thresholds of both adult and pediatric listeners, the presentation level to reach 50% correct performance for the easy word lists was lower than for the hard word lists and that for the disyllable word lists was lower than for the monosyllable word lists. This is consistent with early experimental results of the effects of lexical characteristics on word recognition [4,5,8,9,16]. In both normal-hearing and hearingimpaired listeners, such lexical effects were shown as better recognition performance with easy word lists as compared with hard word lists and better recognition performance with disyllable word lists as compared with monosyllable word lists. Compared with the adults, the pediatric listeners showed a higher word recognition threshold. It is known that the auditory pathway in children does not reach maturity until adolescence [17], which suggests that the ability of speech recognition and
Psychometric properties of the Standard-Chinese LNT 50
50 Adults
Adults
Children
Children
40
30 CD (%)
SRT50 (dB SPL)
40
71
20
30
20
10 10
Slope at 50% correct (%/dB)
0 0
6 5
D−E
D−H
M−E
M−H
Figure 3. The 95% critical difference (CD) values with the disyllable easy (D-E), disyllable hard (D-H), monosyllable easy (M-E), and monosyllable hard (M-H) word lists. Black and white bars represent data from the adults and children, respectively. The error bars represent standard deviation (SD).
4 3 2 1 0
D−E
D−H
M−E
M−H
Figure 2. The speech recognition threshold (SRT50) and slopes at 50% correct with the disyllable easy (D-E), disyllable hard (D-H), monosyllable easy (M-E), and monosyllable hard (M-H) word lists. Black bars represent data from the adults and white bars represent data from the children. The error bars represent standard deviation (SD).
the ability to use contextual information as well as cognitive and sensory functions are still in development in young children. Compared with younger children, older children and adults can better utilize the sensory information and linguistic knowledge for better speech recognition [18]. In a previous study, we showed that there was clearly an effect of age in Mandarin Chinese word recognition in a group of children of aged 3–5 years [8,9]. Therefore, children required higher intensities than adults to reach the same performance in word recognition. The lexical effects were also reflected in the slope data of the psychometric functions (Figure 2, bottom panel). The slopes for disyllable words were steeper than those for the monosyllable words in both children and adult listeners. The slopes for easy words were steeper than those for hard words in pediatric listeners. These results were also consistent with those reported in a previous study, i.e. the easier the words, the steeper the psychometric slopes and the more redundant information, the steeper the psychometric slopes [16]. The values of psychometric slope data were largely in line with those reported in the literature. Dirks et al. [16] showed that the psychometric slope (between
70.7 and 29.3%) for English monosyllable easy words was 4.1% per decibel and that for hard words was 3.8% per decibel in normal-hearing adult listeners. In some other studies on Mandarin Chinese using various word lists, the reported slope values were also consistent with those reported here using the LNT word lists. Han et al. [19] tested Mandarin monosyllabic word recognition and found that the mean slopes of psychometric functions were 4.1% per decibel for normalhearing adults and 2.7% per decibel for hearingimpaired adults. The psychometric slopes of Mandarin disyllabic materials were found to be approximately 8% per decibel at 50% correct for normal-hearing adults [11]. For Cantonese, the psychometric slopes for the disyllable materials were found to be around 7.5% per decibel for normal-hearing adults [12]. The test–retest reliability of speech test materials can be assessed in several ways. Bentler [15] examined the test–retest reliability of the speech-in-noise (SIN) test using the test–retest correlation and the 95% CD values. Similarly, Wilson and McArdle [20] assessed the test–retest reliability of the words-in-noise (WIN) test using the same measures. It is difficult to compare the CD values of various studies due to the drastic differences in test materials (sentences versus words) and presentation levels. In a study with Mandarin phonetically balanced monosyllabic lists at similar presentation levels, Xi and colleagues [14] reported that the CD values were 21.2% for normal-hearing adult listeners. As shown in Figure 3, the overall CD values of the four word categories were 26.6% for adults and 30.0% for children, respectively. It appears that the CD values were greater in the present study. This may be due to the fact that the number of words in the lists of the Standard-Chinese LNT is fewer and that the
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number of subjects is smaller in the present study than in the study by Xi et al. [14].
Conclusion Our study examined the psychometric characteristics of Standard-Chinese LNT in normal-hearing children and adults. We found that adults had lower word recognition thresholds and steeper slopes than those for children. The lexical effects on speech recognition were the same for children and adults, i.e. the speech recognition was more accurate for lexical easy words than for hard words. Therefore, the test materials can be used to evaluate the word recognition performance of hearing-impaired children and adults. Furthermore, the CD values at 95% critical level can be used to assess the effectiveness of intervention or different aided conditions. Future studies are necessary to examine the psychometric properties of the Standard-Chinese LNT materials in the hearing-impaired population.
Acknowledgment The study was supported by the National Natural Science Foundation of China (81170916 and 30872859). Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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