A role for the developing lexicon in phonetic category acquisition

Infants segment words from fluent speech during the same period when they are learning phonetic categories, yet accounts of phonetic category acquisition typically ignore information about the words in which sounds appear. We use a Bayesian model to illustrate how feedback from segmented words might constrain phonetic category learning by providing information about which sounds occur together in words. Simulations demonstrate that word-level information can successfully disambiguate overlapping English vowel categories. Learning patterns in the model are shown to parallel human behavior from artificial language learning tasks. These findings point to a central role for the developing lexicon in phonetic category acquisition and provide a framework for incorporating top-down constraints into models of category learning

Modeling Phonological Processing for Children with Mild Intellectual Disabilities: The Relationship between Underlying Phonological Abilities and Associated Language Variables

The structure of phonological processing for typically developing children has been debated over the past two decades. Recent research has indicated that phonological processing is best explained by a single underlying phonological ability (e.g., Anthony and Lonigan, 2004). The current study had two goals. The first goal was to determine the structure of phonological processing for school-age children with mild intellectual disabilities (MID). The second goal was to determine the relationship between the components of phonological processing and expressive and receptive language ability. The participants were 222 school-age children identified by their schools as having MID. Confirmatory factor analysis was utilized to determine the structure of phonological processing. The results indicated that a model with one phonological awareness factor and one naming speed factor explained the data better than competing models with a single latent factor or more than two latent factors. There was a negative significant relationship between phonological processing and naming speed. There were positive bivariate relationships between phonological processing and expressive and receptive language. There were negative bivariate relationships between naming speed and expressive and receptive language. These results are consistent with other research findings with typically developing children, indicating a similarity in the relationships between phonological process and language for children with MID. Theoretical and instructional implications are discussed

Brownian dynamics for the vowel sounds of human language

We present a model for the evolution of vowel sounds in human languages, in which words behave as Brownian particles diffusing in acoustic space, interacting via the vowel sounds they contain. Interaction forces, derived from a simple model of the language learning process, are attractive at short range and repulsive at long range. This generates sets of acoustic clusters, each representing a distinct sound, which form patterns with similar statistical properties to real vowel systems. Our formulation may be generalised to account for spontaneous self actuating shifts in system structure which are observed in real languages, and to combine in one model two previously distinct theories of vowel system structure: dispersion theory, which assumes that vowel systems maximize contrasts between sounds, and quantal theory, according to which non linear relationships between articulatory and acoustic parameters are the source of patterns in sound inventories. By formulating the dynamics of vowel sounds using inter-particle forces, we also provide a simple unifi ed description of the linguistic notion of push and pull dynamics in vowel systems.The authors are grateful to the Royal Society for an APEX award (2018-2020), funded by the Leverhulme trust

The impact of spectrally asynchronous delay on the intelligibility of conversational speech

Conversationally spoken speech is rampant with rapidly changing and complex acoustic cues that individuals are able to hear, process, and encode to meaning. For many hearing-impaired listeners, a hearing aid is necessary to hear these spectral and temporal acoustic cues of speech. For listeners with mild-moderate high frequency sensorineural hearing loss, open-fit digital signal processing (DSP) hearing aids are the most common amplification option. Open-fit DSP hearing aids introduce a spectrally asynchronous delay to the acoustic signal by allowing audible low frequency information to pass to the eardrum unimpeded while the aid delivers amplified high frequency sounds to the eardrum that has a delayed onset relative to the natural pathway of sound. These spectrally asynchronous delays may disrupt the natural acoustic pattern of speech. The primary goal of this study is to measure the effect of spectrally asynchronous delay on the intelligibility of conversational speech by normal-hearing and hearing-impaired listeners. A group of normal-hearing listeners (n = 25) and listeners with mild-moderate high frequency sensorineural hearing loss (n = 25) participated in this study. The acoustic stimuli included 200 conversationally-spoken recordings of the low predictability sentences from the revised speech perception in noise test (r-SPIN). These 200 sentences were modified to control for audibility for the hearing-impaired group and so that the acoustic energy above 2 kHz was delayed by either 0 ms (control), 4ms, 8ms, or 32 ms relative to the low frequency energy. The data were analyzed in order to find the effect of each of the four delay conditions on the intelligibility of the final key word of each sentence. Normal-hearing listeners were minimally affected by the asynchronous delay. However, the hearing-impaired listeners were deleteriously affected by increasing amounts of spectrally asynchronous delay. Although the hearing-impaired listeners performed well overall in their perception of conversationally spoken speech in quiet, the intelligibility of conversationally spoken sentences significantly decreased when the delay values were equal to or greater than 4 ms. Therefore, hearing aid manufacturers need to restrict the amount of delay introduced by DSP so that it does not distort the acoustic patterns of conversational speech

Cracking the Code: An effectiveness study

This study employed a pre-test post-test group design to evaluate the effectiveness of the Cracking the Code (CtC) Program with students aged 3;8–5;4. CtC is a teacher implemented classroom based program, designed to target phonological awareness (PA) and alphabet knowledge. Results showed that children in the experimental condition improved significantly more in PA, alphabet knowledge, non-word reading and non-word spelling after the intervention than the control group, thus demonstrating the effectiveness of CtC

The Design and Application of an Acoustic Front-End for Use in Speech Interfaces

This thesis describes the design, implementation, and application of an acoustic front-end. Such front-ends constitute the core of automatic speech recognition systems. The front-end whose development is reported here has been designed for speaker-independent large vocabulary recognition. The emphasis of this thesis is more one of design than of application. This work exploits the current state-of-the-art in speech recognition research, for example, the use of Hidden Markov Models. It describes the steps taken to build a speaker-independent large vocabulary system from signal processing, through pattern matching, to language modelling. An acoustic front-end can be considered as a multi-stage process, each of which requires the specification of many parameters. Some parameters have fundamental consequences for the ultimate application of the front-end. Therefore, a major part of this thesis is concerned with their analysis and specification. Experiments were carried out to determine the characteristics of individual parameters, the results of which were then used to motivate particular parameter settings. The thesis concludes with some applications that point out, not only the power of the resulting acoustic front-end, but also its limitations

Early identification and intervention with kindergartners at risk for reading failure : a district-wide prevention program using a multiple gating approach.

This study is part of an action research project designed to model a district-wide early identification and intervention program for Kindergartners at risk for reading failure. The project was designed to model quality professional development in the area of early literacy for Kindergarten teachers, the use of a multi-gating procedure for identifying those children most likely to benefit from extra support, training for paraprofessionals to provide support to identified low performing students, and the use of a “response to intervention” approach for determining level of intensity of intervention. This study evaluates the relative effectiveness of the two research-validated curricula chosen as strategic interventions for improving outcomes on early literacy indicators of at-risk Kindergarten students. Both curricula were delivered in small groups by classroom aides who received brief training. A second part of the study evaluates the effectiveness of individually designed, intensified interventions for those children whose achievement did not improve sufficiently under conditions of small group instruction. A third section examined factors affecting teacher motivation to participate in the project and to embrace new teaching and assessment methods

Hearing in dementia: defining deficits and assessing impact

The association between hearing impairment and dementia has emerged as a major public health challenge, with significant opportunities for earlier diagnosis, treatment and prevention. However, the nature of this association has not been defined. We hear with our brains, particularly within the complex soundscapes of everyday life: neurodegenerative pathologies target the auditory brain and are therefore predicted to damage hearing function early and profoundly. Here I present evidence for this proposition, based on structural and functional features of auditory brain organisation that confer vulnerability to neurodegeneration, the extensive, reciprocal interplay between ‘peripheral’ and ‘central’ hearing dysfunction, and recently characterised auditory signatures of canonical neurodegenerative dementias (Alzheimer’s disease and frontotemporal dementia). In chapter 3, I examine pure tone audiometric thresholds in AD and FTD syndromes and explore the functional interplay between the auditory brain and auditory periphery by assessing the contribution of auditory cognitive factors on pure tone detection. In chapter 4, I develop this further by examining the processing of degraded speech signals, leveraging the increased importance of top-down integrative and predictive mechanisms on resolving impoverished bottom-up sensory encoding. In chapter 5, I use a more discrete test of phonological processing to focus in on a specific brain region that is an early target in logopenic aphasia, to explore the potential of auditory cognitive tests as disease specific functional biomarkers. Finally, in chapter 6, I use auditory symptom questionnaires to capture real-world hearing in daily life amongst patients with dementia as well as their carers and measure how this correlates with audiometric performance and degraded speech processing. I call for a clinical assessment of real-world hearing in these diseases that moves beyond pure tone perception to the development of novel auditory ‘cognitive stress tests’ and proximity markers for the early diagnosis of dementia and management strategies that harness retained auditory plasticity

Whole Word Phonetic Displays for Speech Articulation Training

The main objective of this dissertation is to investigate and develop speech recognition technologies for speech training for people with hearing impairments. During the course of this work, a computer aided speech training system for articulation speech training was also designed and implemented. The speech training system places emphasis on displays to improve children\u27s pronunciation of isolated Consonant-Vowel-Consonant (CVC) words, with displays at both the phonetic level and whole word level. This dissertation presents two hybrid methods for combining Hidden Markov Models (HMMs) and Neural Networks (NNs) for speech recognition. The first method uses NN outputs as posterior probability estimators for HMMs. The second method uses NNs to transform the original speech features to normalized features with reduced correlation. Based on experimental testing, both of the hybrid methods give higher accuracy than standard HMM methods. The second method, using the NN to create normalized features, outperforms the first method in terms of accuracy. Several graphical displays were developed to provide real time visual feedback to users, to help them to improve and correct their pronunciations