A cryptographic security architecture constitutes the collection of hardware and software which protects and controls the use of encryption keys and similar cryptovariables. This thesis presents a design for a portable, flexible high-security architecture based on a traditional computer security model. Behind the API it consists of a kernel implementing a reference monitor which controls access to security-relevant objects and attributes based on a configurable security policy. Layered over the kernel are various objects which abstract core functionality such as encryption and digital signature capabilities, certificate management and secure sessions and data enveloping (email encryption). The kernel itself uses a novel design which bases its security policy on a collection of filter rules enforcing a cryptographic module-specific security policy. Since the enforcement mechanism (&e kernel) is completely independent of the policy database (the filter rules), it is possible to change the behaviour of the architecture by updating the policy database without having to make any changes to the kernel itself. This clear separation of policy and mechanism contrasts with current cryptographic security architecture approaches which, if they enforce controls at all, hardcode them into the implementation, making it difficult to either change the controls to meet application-specific requirements or to assess and verify them. To provide assurance of the correctness of the implementation, this thesis presents a design and implementation process which has been selected to allow the implementation to be verified in a manner which can reassure an outsider that it does indeed function as required. In addition to producing verification evidence which is understandable to the average user, the verification process for an implementation needs to be fully automated and capable of being taken down to the level of running code, an approach which is currently impossible with traditional methods. The approach presented here makes it possible to perform verification at this level, something which had previously been classed as "beyond Al" (that is, not achievable using any known technology). The versatility of the architecture presented here has been proven through its use in implementations ranging from l6-bit microcontrollers through to supercomputers, as well as a number of unusual areas such as security modules in ATMs and cryptographic coprocessors for general-purpose computers. / Note: Updated version of the thesis now published as Gutmann, P (2004). Cryptographic security architecture: design and verification. New York: Springer. ISBN 9780387953876.

Vocal efficiency is a measure of the efficiency of the energy conversion process from aerodynamic power to acoustic power. Few studies have been conducted to measure vocal efficiency in trained singers to determine whether "vocal athletes" are more efficient than non-singers. Data were collected from 20 trained singers (10 male and 10 female) and 20 non-singers (10 male and 10 female) to determine if there were any significant differences between the two groups. During the recording, each participant produced a series of syllables at combinations of three different levels of pitch and loudness. The acoustic and aerodynamic data were analyzed to reveal any statistically significant differences in vocal efficiency between singers and non-singers. The singers were significantly more efficient than non-singers in only two of the nine conditions. Singers had significantly higher subglottic pressure and resistance values. More differences were found between men and women, in that males produced greater flow, but females consistently produced higher sound pressure level values. Acoustic analyses were also performed and this revealed that singers had significantly greater fundamental frequency variability during speech, as reflected in a higher semitone standard deviation for a reading passage. It was also found that males had higher maximum phonation times and a greater long-term average spectrum standard deviation. Vocal beauty ratings were significantly higher for singers than non-singers.

The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Thai monosyllabic word lists to use in the measurement of word recognition ability. A native male and female talker from Thailand, who were judged to have a standard Thai dialect, participated as talkers in digitally recording familiar Thai monosyllabic words. Twenty native Thai participants 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 200 words with the highest raw scores 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 monosyllabic word data were analyzed using logistic regression to calculate threshold and slope for each list and half-list.

Although recent literature suggests that fatigue influences the communication of people with multiple sclerosis (MS), its relationship to acoustic measures of speech, specifically formant transitions during diphthongs, has not been explored. In the present study, 11 participants diagnosed with MS, two of whom were perceptually dysarthric, and 12 control subjects were recorded as they performed selected speech tasks in both the morning and the afternoon. Before each recording session, participants rated their fatigue level. The participants with MS gave significantly higher ratings of fatigue than the control group. The speakers with MS had longer diphthong durations in a non-fatigued state, but not in a fatigued state, which was indicative of the variability in this group of speakers. Fatigue was not shown to affect any other acoustic variables. This finding may be attributable to the mildness of the speech impairment of this sample of speakers with MS.

This study examined how retelling stories with a variety different background noise conditions affected the communicative experiences of people with aphasia (PWA). Participants included 11 adults with mild to moderate aphasia and 11 age- and gender-matched controls. Participants participated in a semi-structured interview immediately following the experimental measure where they were asked open-ended questions regarding their experience retelling stories and how those experiences related to their everyday lives. Results revealed three themes related to how participants responded to communicating in noise: (a) cognitive reactions, (b) emotional reactions, and (c) social reactions. The findings suggest that PWA exert more effort when speaking in noise and benefit from supportive communication partners more than control participants. Findings also suggest that PWA who reported a lack of strategies were more likely to adopt maladaptive strategies. Explicit training for communication partners and PWA may help PWA more effectively cope with the challenges of difficult noise situations which may lead to increased confidence and social participation.

The purpose of this study was to examine how varying pause lengths in speech of people with aphasia (PWA) influences listeners' perceptions. The study specifically assesses listeners' perceptions of communicative effectiveness and speaker likability. Speech samples from six people with nonfluent or fluent aphasia were obtained from a previous study conducted by Harmon (2018). The speech samples were modified to create four sets of stimuli, including the original recordings, normalized within utterance pauses, normalized between utterance pauses, and normalized for both within and between utterance pauses. Forty listeners rated each of the speech samples based on the perceived communicative effectiveness and likability using a visual analog scale. Communicative effectiveness and likability ratings were significantly higher for the normalized within utterance and normalized within and between utterance conditions when compared to the baseline and normalized between utterance conditions. Both male and female listeners rated the recordings from nonfluent aphasic speakers lower than recording from speakers with fluent aphasia. Results of the study provide preliminary evidence that pauses in speech of PWA influence listeners' perceptions of communicative effectiveness and likability of the speaker. It is hoped that additional research regarding pause in speech of PWA will be conducted to determine if targeting pause in speech-language therapy will improve the communication of PWA.

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This study evaluated the impact of a clinically-based Speech Entrainment (SE) approach on content word production and phonemic accuracy in a single-subject design involving a stroke survivor with nonfluent aphasia and acquired apraxia of speech (AOS). Due to the emergence of the COVID-19 pandemic, the study was conducted entirely through remotely-delivered telepractice using the online conferencing platform Zoom. SE is a current speech-language treatment that aims to improve the expressive deficits typically encountered in individuals with nonfluent aphasia and AOS through consistent practice in mimicry of pre-recorded audiovisual supports. This single-subject, multiple-baseline across behaviors design utilized a clinically-driven, patient-centered SE approach to evaluate the generalization of treatment effects to trained and untrained pre-scripted targets across the participant's daily communicative contexts. Treatment stimuli were developed with direct participation by the participant and his family in accordance with the principles of patient-centered treatment design. The participant underwent an 8-week treatment period in which SE was used to facilitate repeated practice using audiovisual recordings of pre-scripted stimuli across six categories. Preliminary results suggest a positive impact on content word production and phonemic accuracy for trained targets with and without the use of the audiovisual supports. This study also aimed to evaluate the potential for SE to become a longer-term communication support; a suggestion made by authors of previous research using SE. Recommendations for further research in clinically-based SE treatment and use of SE as a long-term communication support are made.

Research has demonstrated that automated grammatical tagging is fast and accurate for both English and Spanish child language, but there has been no research done regarding its accuracy with bilingual children. The present study examined this topic using English and Spanish language samples taken from 254 children living in the United States. The subjects included school-aged children enrolled in public schools in the United States in grades 2, 3, or 5. The present study found high automated grammatical tagging accuracy scores for both English (M = 96.4%) and Spanish (M = 96.8%). The study suggests that automated grammatical analysis has potential to be a valuable tool for clinicians in the analysis of the language of bilingual children.

Speech audiometry is an important aspect of audiological testing. One aspect of speech audiometry is the measurement of an individual's speech reception threshold (SRT). Materials needed to measure the SRT are available in many languages; however, recorded materials for the Mongolian Language are not widely available. The purpose of this study was to develop a list of psychometrically equivalent words for evaluating the hearing abilities of native Mongolian speaking individuals. A set of 90 commonly used bisyllabic Mongolian words were digitally recorded by a male and female talker of Mongolian and then evaluated by 20 native Mongolian listeners. A final list of 28 words with relatively steep psychometric function slopes were selected and digitally adjusted to reduce intensity threshold variability among words. Digital recordings of the 28 psychometrically equivalent bisyllabic words are available on compact disc to facilitate SRT testing of native Mongolian speakers.