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Introduction: The purpose of the study was to analyze the differences in word recognition abilities between the Auditec (male) and VA (female) speakers for the Northwestern University Auditory Test No. 6 (NU-6) word lists for young adults with normal hearing for pure tones. Based on the literature, the hypothesis was recognition performance would be better on the Auditec version than on the VA version. The results were considered with respect to the mean data, individual subject data, and individual word data. Methods: Twelve young listeners with normal-hearing for pure tones (≤20 dB HL) participated (M = 24 years). The pure-tone thresholds were obtained using an automated test protocol. The pure-tone average (PTA) at 500, 1000, and 2000 Hz in the first session was used to reference the presentation levels of the words [-2 to 28 dB sensation level (SL) in 6-dB steps]. Each participant was presented 1200 recorded words (100 words by six presentation levels by two speakers), over three, 1-hour sessions. The NU-6 words, which were compiled with a waveform editor and in-house routines, were presented in a randomized order and at randomized presentation levels. The participants completed a questionnaire to determine the perceived difficulty level for each speaker. Results: The overall recognition performances on the Auditec and VA versions of NU-6 were 71.4% and 64.1% respectively. All subjects performed better on the Auditec version. Recognition performances on the two versions were nearly identical at higher presentation levels. The difference between the two 50% points on the overall mean psychometric functions was 3.3 dB (Auditec, 3.8-dB SL; VA, 7.0-dB SL), with equivalent slopes (4.9 and 4.8%/dB respectively). Using the Spearman- Kärber equation, the difference between the two 50% points on each of the 200 words was 2.6 dB (Auditec, M = 5.3-dB SL, SD = 3.7 dB; VA, M = 7.9-dB SL, SD = 3.7 dB), which was a significant difference. A bivariate lot of individual word performances demonstrated that Auditec had had 140 words with better performances, VA had 47 words with better performances, and 13 words were equal. The questionnaire revealed that 11 of the 12 participants indicated that the Auditec version of the NU-6 was easier to understand. Conclusions: Overall, recognition performance was better on the Auditec version but at high presentation levels, recognition performance was equivalent on both versions of NU-6. At the lower presentation levels, recognition performance was poorer with the VA speaker. It should be noted that calibration differences could account for the differences.

The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Tongan bisyllabic word lists for use in measurement of word recognition testing. Commonly used bisyllabic words were digitally recorded by male and female native talkers of Tongan. The psychometric performance of the words was measured at ten intensity levels (- 5 to 40 dB HL) in 5 dB increments by 20 listeners with normal hearing acuity. The 200 words with the highest rate of listener identification were included in four relatively psychometrically equivalent word lists of 50 words each and eight half-lists of 25 words each. Using logistic regression, the mean psychometric slope across the created word lists at 50% intelligibility was found to be 6.3%/dB for materials created from the male talker recordings and 6.2%/dB for the female talker recordings. To increase auditory homogeneity of the word recognition lists, the intensity of words in each list was digitally adjusted so that the threshold of each list was equal to the midpoint between the mean thresholds of the male and female half-lists. Digital recordings of the psychometrically equivalent word recognition lists are available on compact disc.

Hearing can be evaluated through the presentation of tones or speech. Speech audiometry determines an individual's speech recognition threshold and word recognition score. Traditionally these materials were developed using familiar, frequently used, monosyllabic words. Currently, there are various types of word recognition materials including those which use word lists, short half-lists, and materials which use sentences level stimuli with competing noise. Word recognition materials were first developed in Standard American English; today, materials are now readily available in many other languages. When possible, word recognition materials are developed digitally to standardize their presentation. Currently, no recorded word recognition materials are commercially available for native speakers of Samoan. Bisyllablic words were chosen, rated, recorded, and prepared for subject testing. All subjects were native speakers of Samoan with adequate hearing, meeting required standards for audiological research. Results indicated that no significant differences were found among bisyllabic word lists or half-lists developed in the current study. Subject word recognition performance and psychometric function slopes were comparable to the results of other related studies. All materials were recorded onto CD and made commercially available. It is hoped that this resource will aid trained professionals in the diagnosis and remediation of hearing loss in Samoan-speaking individuals.

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.

Thesis (Ed.D.)--Boston University.

Most previous research has explored how words are processed in isolation. However, reading is a complex process where an interplay of various factors affects word identification. Moreover, previous research has mainly focused on alphabetical languages, so extension of the existent findings to non-alphabetical languages is crucial. The current dissertation uses natural reading paradigms to study eye-movements and neurophysiological correlates of the statistical properties of words that affect word recognition during natural reading in English and Chinese. Chapter 2 concerns the time-courses of word frequency and semantic similarity effects in the reading of English derived words. Previous research pointed to a paradox where behavioural experimental techniques showed earlier signatures of these properties than neuro-imaging techniques. By combining eye-tracking and EEG and applying analytical techniques that target the onset of these effects, this study aims at investigating this paradox. Results still show that neurophysiological responses are either largely absent or appear at the same time as shown in eye-movement data. Chapter 3 shows that the existence of spelling errors negatively impacts the recognition of correct spellings in Chinese. This is revealed by the “spelling entropy effect”, which measures the uncertainty about choosing between correct and alternative spelling variants. This is the first study that used co-registration of eye-tracking and EEG to explore the behavioral and neurophysiological signatures of this uncertainty. Chapter 4 studies how segmentation probabilities influence word segmentation and identification when reading Chinese. The results reveal that space becomes beneficial only when located at places where segmentation probability is considered high. This study is among the first to show beneficial effects of spacing at the sentence level and demonstrates how segmentation probabilities play a crucial role in Chinese word segmentation. Cumulatively, the results obtained point to the existence of numerous factors involved in word identification in both alphabetic and logographic languages, which should be explored using natural reading experimental paradigms, such as co-registration of EEG and eye-tracking, for obtaining a multifaceted view of word recognition processes. / Thesis / Doctor of Philosophy (PhD)

No description available.