Despite the documented need for reliable speech audiometry materials for measures such as speech recognition threshold and word recognition score, such recorded materials are not available in the Vietnamese language. The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Vietnamese bisyllabic and monosyllabic word lists for use in the measurement of speech recognition and word recognition ability, respectively. To create the speech recognition threshold materials, common Vietnamese bisyllabic words were digitally recorded by male and female talkers of Vietnamese and presented for evaluation to 20 native speakers of Vietnamese with normal hearing. Based on listener response, a set of 48 bisyllabic words with relatively steep psychometric function slopes were selected and digitally adjusted to ensure equivalency for psychometric function slope and to equate threshold to the mean pure-tone average for the test participants. To create the word recognition materials, 250 words were digitally recorded by one male and one female talker of Vietnamese and presented to the listeners for evaluation. Based on listener response, 200 words were selected and divided into 4 lists of 50 monosyllabic words and 8 half-lists of 25 monosyllabic words. The lists were digitally adjusted to ensure intensity threshold equivalency. The resulting mean psychometric function slopes at 50% for the speech recognition threshold materials is 11.3%/dB for the male talker and 10.2%/dB for the female talker. Analysis of the word recognition materials indicates no significant difference between the lists or half-lists. The mean psychometric function slope at 50% for the monosyllabic lists and half-lists is 5.1%/dB for the male recordings and 5.2%/dB for the female recordings. The results of the current study are comparable to those found in other languages. Digital recordings of the bisyllabic and monosyllabic word lists are available on compact disc.

THE DISSERTATION IS IN AFRIKAANS: The multi-linguistic and multi-cultural population of South Africa poses some unique challenges for valid and reliable service delivery by South African audiologists and acousticians, specifically when conducting valid and reliable speech audiometry evaluations. This is examined in the South African context, and set the base for the main aim of this study, namely the comparison of the ideal criteria for speech audiometry with the South African clinical practice of speech audiometry. Many variables can be identified in the course of the test stimuli and subsequent response when conducting speech audiometry. These variables can be divided into two categories, namely stimulus related variables (test content and test procedure) and test subject related variables. The variables are examined in light of the multi-linguistic and multi-cultural South African context, because of the challenges posed by this context to the South African audiologist. The study is conducted in three different phases, according to three sub aims. A thorough review of the subject literature was done to identify ideal criteria for speech audiometry. A questionnaire was sent to South African audiologists and acousticians, to examine the present clinical practice of speech audiometry in South Africa, and compare it to the criteria suggested in the literature in order to investigate the attainability of criteria and to identify problem areas. The results show low comparison regarding test content between the ideal criteria and South African clinical practice, especially because South African audiologists do not use a test battery consisting of different types of test material. Low comparison can be seen regarding the selection of test items, length of lists and degree of difficulty. Low comparison can also be seen with test procedure, mainly because audiologists rarely use pre-recorded test materials. High levels of comparison are found regarding presentation levels and test environment. With test subject variables, a discrepancy is also found between the ideal criteria and South African clinical practice, mainly because tests are not always conducted in the test subjects’ first language. By using the identified deficiencies in the clinical practice of speech audiometry in South Africa as a starting point, one can use further research to reach the ideal, namely the ideal criteria of conducting speech audiometry. The conclusions of this study can be used as suggestions for solutions for the unique problems that the practicing audiologist in South Africa has to deal with. The complexity of these problems will need further attention from researchers in this and other fields of study. / Dissertation (MCommunication Pathology)--University of Pretoria, 2007. / Speech-Language Pathology and Audiology / Unrestricted

Dichotic tests evaluate binaural integration through simultaneous presentation of different stimuli to each ear of a listener who has normal hearing sensitivity in both ears. Dichotic listening deficits may lead to problems with language, communication, reading, or academic performance. If accurately identified, dichotic deficits may be treatable with listening training or managed with accommodation. However, it is not clear which of several commercially-available dichotic test recordings are best for audiologists to use when assessing binaural integration in children. Literature review revealed limited evidence of reliability, accuracy, usefulness, or value for dichotic tests applied to children. Of 11 dichotic tests identified, five reported some evidence of test-retest reliability. Correlation between results on repeated administration was moderate to good (r=0.59 to 0.92). Evidence of accuracy was identified for 5 tests but was not generalizable due to significant limitations in study design. No evidence was found to either support or dispute claims of usefulness or value. Since reliability is a necessary prerequisite for good test performance, we sought to directly compare test-retest reliability for three dichotic measures: SCAN-3 Competing Words (CW), Musiek's Double Dichotic Digits (DD-M), and Bergen Dichotic Listening Test with Consonant-Vowel Syllables (CV-B). Sixty English-speaking children, 7-14 years old with normal hearing, had a single study-visit during which each test was administered twice. Changes on retest were compared to binomial model predictions, summarized by within-subject standard deviation (Sw), and compared among tests. Correlates of variance were explored. All 3 tests had reliability within bounds predicted by binomial model. Forty-item scores were more reliable (Sw=5%) than those based on 20-30 items (Sw=6-8%). No associations between participant characteristics and reliability were found. CW and DD-M were evaluated for evidence of agreement and decision consistency. Although participants were rank ordered similarly by right ear (ρ = 0.58), left ear (ρ = 0.51) and total (ρ = 0.73) scores, the tests did not agree on ranking by inter-aural asymmetry (ρ =0.18). CW and DD-M did not agree on direction of ear advantage (κ = 0.01, p = 0.93) and had poor agreement on which children displayed dichotic deficits (κ = 0.22, p < 0.01). DD identified significantly more participants with deficits (n=18) than CW (n=3) (p < 0.001). Although dichotic procedures show moderate reliability, their precision is limited. Assessment of their accuracy is limited by the absence of a widely-accepted gold standard reference test, but two commonly used tests failed to agree on which children had deficits. The data do not yet support routine clinical use of dichotic tests of binaural integration with children. Additional research is needed to determine if there are any conditions under which dichotic procedures demonstrate usefulness or value.

While recorded speech audiometry materials have been developed in Spanish for adults, currently there are no speech audiometry materials available in Spanish that are suitable for a pediatric population. Thus, the purposes of this study were (a) to analyze Spanish bisyllabic words previously developed for adults to determine the words' appropriateness when testing word recognition scores in native Spanish-speaking children and (b) to compare the logistic regressions results from the Spanish adult data obtained in a previous study with the logistic regressions from Spanish pediatric data obtained in the present study. Using common-use children's dictionaries in the Spanish language, a subset of child-appropriate words was adapted from a set of materials developed for Spanish adults. A total of 129 frequently used bisyllabic words were chosen; the words were split into five lists; four lists contained 26 words and one list contained 25 words; each was digitally recorded by both male and female Spanish talkers. Twenty native Spanish-speaking children with normal hearing between the ages of four and eight years were selected to listen to words to obtain psychometric functions. Each word was presented to the listener at 5 levels of intensity from -5 to 35 dB HL in increments of 10 dB. Custom software was used to control randomization, timing, and presentation of the words. The participants were not familiarized with the words prior to testing. The words received a ranked order based on performance to create lists and half-lists that were equivalent. Logistic regression was used to calculate psychometric functions for the lists and half-lists. Subsequently, a chi-square analysis was completed. The analysis revealed no statistical differences among the lists and half-lists for either male or female talkers. The mean bisyllabic psychometric function slopes for lists and half-lists were 5.0%/dB for the male-talker words and 5.2%/dB for the female-talker words. The 50% threshold for male and female were 16.2 dB HL and 15.5 dB HL, respectively.

Speech audiometry is the aspect of audiology that provides critical information on how individuals hear one of the most important sounds of daily life: speech. The speech recognition threshold (SRT) is a measure of speech audiometry that is widely used to provide information on an individual's capacity to hear speech. Over time, researchers and clinicians have worked to improve the SRT by developing and modifying a variety of word lists to be used during testing. Eventually, spondaic words were selected as the best stimuli for the SRT. The spondaic words had to meet four criteria: familiarity, phonetic dissimilarity, normal sampling of English sounds, and homogeneity with respect to audibility. This study examined the aspect of homogeneity with regard to slope of the psychometric function. Specifically, whether slope of the psychometric function had an effect on the number of words used to obtain the SRT, and thus reduce test time, as well as whether slope had an effect on the relationship between the SRT and the pure-tone average (PTA). It was hypothesized that words with a steep slope would significantly reduce test time and yield a close SRT-PTA agreement. Three word lists (steep, medium, and shallow sloping words), all recorded by a male talker, were used to obtain the SRT on 40 participants (ages 18-30 years). Statistical analysis showed significant differences in the number of words to obtain the SRT and the SRT-PTA agreement. However, when the differences were examined from a clinical perspective, the results were negligible. When compared with words with medium and steep slopes, words with shallow slope required an average of four extra words to obtain the SRT, which does not result in a meaningful reduction in test time. For clinical purposes, it appears that the slope of the psychometric function does not need to be taken into consideration for the SRT. Clinicians may use a variety of words as long as they meet the original four criteria for selection of spondees.

Speech audiometry has long been a component of a thorough audiological examination. The speech recognition threshold (SRT) measurement is perhaps the most widely used measurement in speech audiometry. For decades, researchers and clinicians have worked to create and fine-tune word lists that for use in SRT testing; their aim being to improve the accuracy for classifying a client's ability to hear and comprehend speech. Experts in the field have agreed to follow four tenets of speech audiometry when selecting word sets. This study examined whether improvement to stimulus lists for SRT measurement could be made in regards to the tenet of homogeneity with respect to audibility if the slope of the psychometric function were a selection consideration. The study was performed with the hypothesis that steeply sloping words would significantly reduce the number of words needed to obtain the SRT. Three word lists, all recorded by a female talker, comprising of steeply sloping words, medium sloping words, and shallow sloping words, were used in the study. Participants with normal hearing between the ages of 18 and 30 years provided data that was used to calculate SRT measurements for all three lists from each ear. The results showed a significant difference in the number of words needed to obtain the SRT when comparing the steep and shallow word sets and the shallow and medium word sets. Steeply sloping words required fewer words to obtain the SRT, M = 17.02. Shallow sloping words required the most words, M = 18.88, amounting to a difference of 1.86 words. While statistically different, a reduction by fewer than 2 words during the course of SRT testing will not equate to a substantial saving of time for the clinician. For clinical application, the slope of the psychometric function of the words used in SRT measurement need not be a primary consideration when developing stimulus lists.

While there is a clear and immediate need for reliable speech audiometry materials to evaluate the speech recognition threshold (SRT), these recorded materials are not available in Cebuano, a language of the Philippines with 15.8 million speakers. The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Cebuano trisyllabic words for use in measuring the SRT. To create the SRT materials, common Cebuano trisyllabic words were digitally recorded by a male talker of Cebuano and presented for evaluation to 20 native speakers of Cebuano with normal hearing. Based on psychometric performance, a set of 21 trisyllabic words with a psychometric function slope >7%/dB that allowed threshold adjustments to the pure tone average were selected and digitally adjusted. The resulting mean psychometric function slopes at 50% for the 21 SRT trisyllabic materials was 10.2%/dB. The results of the current study are comparable to those found in other languages. Digital recordings of the trisyllabic words are available on compact disc.

The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Arabic monosyllabic word lists to use in the measurement of the word recognition score. Familiar Arabic monosyllabic words were digitally recorded by a native male talker from Jordan who was judged to have a standard Arabic dialect. Twenty native Arabic participants with normal hearing were used as subjects to determine the percentage of correct word recognition for each word at 10 intensity levels ranging from -5 to 40 dB HL in 5 dB increments. The monosyllabic word data were analyzed using logistic regression. The words producing the steepest psychometric function were included in the final word lists. Four lists of 50 words each were created and eight half-lists (25 words each) were created from the four lists. A Chi-square analysis was performed, revealing no statistical differences among the lists and half-lists. The mean monosyllabic psychometric function slopes at 50% for lists and half-lists were 4.8%/dB.

Within recent decades speech audiometry materials have been developed in various languages in order to more accurately identify and evaluate hearing impairment in native speakers. This advantage, however, is not available to native Cebuano speakers. The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Cebuano bisyllabic word lists for use in measuring word recognition ability. This process began with recording 260 commonly used bisyllabic Cebuano words by a native speaker noted for his quality and pleasantness of speech in his native tongue. These recordings were then evaluated by 20 normally hearing native Cebuano listeners (21 to 63 years old). Of these words, 200 were selected and then divided into 4 lists of 50 bisyllabic words and 8 half-lists of 25 bisyllabic words. Statistical analysis of the word recognition materials found no significant difference among the lists or half-lists. The mean psychometric function slope at 50% for the bisyllabic word lists and half-lists is 7.3%/dB. The mean 50% threshold for the lists was 19.7 dB HL (SD = 0.1dB). Adjustments were not necessary. The results of the current study are comparable to those found in other languages. Digital recordings of the bisyllabic word lists are available on compact disc.

The purpose of this study was to use previously recorded Spanish trisyllabic words tested on adults in the measurement of the speech recognition threshold of Spanish-speaking children in order to (a) determine the words' appropriateness when testing children and (b) compare psychometric functions between adults and children. A selection of 28 frequently used trisyllabic words was chosen from previously recorded samples of male and female adult native speakers of Spanish. These words were then presented to 20 native Spanish-speaking children with normal hearing between the ages of 4 and 8 years. The words were presented starting at -5 dB HL and ascended in 5 dB increments until the presentation level reached 15 dB HL. Using logistic regression, psychometric functions were calculated for each word. Resulting pediatric thresholds were found to be 8.7 dB higher for male talkers and 11.0 dB higher for female talkers than previously reported adult thresholds. These results indicate a clinically significant threshold difference between pediatric and adult populations. Future research should be conducted to measure the speech recognition threshold (SRT) in children of varying ages to determine the age at which the SRT approximates with adult performance.