In many previous physiological and psychoacoustic studies, Schroeder-phase masking (using Schroeder harmonic complexes to mask other sounds) has proven useful in understanding different aspects of cochlear function, particularly the phase curvature of the cochlea and cochlear nonlinearity. The common method of measuring Schroeder-phase masking functions uses a very time consuming three-alternative forced choice (3AFC) process, which limits its research and clinical usefulness. This thesis describes a fast method for measuring Schroeder-phase masking functions that we developed to address this problem. By adapting the Békésy tracking technique, we demonstrate how the measurement time can be reliably shortened by almost 80% in comparison to the commonly-used method. Using the fast method, we have demonstrated that the difference in masking effectiveness produced by different phases of Schroeder maskers (known as the ‘phase effect’) is reduced in conditions where cochlear non-linearity is expected to be reduced (i.e. at low intensity levels and in sensorineural hearing loss subjects) – findings which are consistent with previous studies. The possible involvement of other mechanisms in producing the Schroeder phase effect (particularly the medial olivocochlear (MOC) reflex) is discussed. Given the shorter testing time and higher resolution data it can give, the fast method can be a useful tool in estimating cochlear phase curvature. The reduction in testing time in particular may significantly aid the investigation of different aspects of cochlear function which might have been limited by the long testing time given by the commonly-used method.

Σκοπός: Σκοπός της μελέτης ήταν η αξιολόγηση της δυνατότητας πρώιμης διάγνωσης της νόσου Ménière με τη χρήση ηχοκάλυψης χαμηλής συχνότητας. Υλικό και μέθοδος: Τριανταπέντε ασθενείς που έπασχαν από τη νόσο Ménière εξετάστηκαν επανειλημμένα κατά την πορεία της νόσου τους. Τα αποτελέσματα των ασθενών αυτών συγκρίθηκαν με αυτά που ελήφθησαν από 10 αυτιά με φυσιολογική ακοή και 40 αυτιά με βαρηκοΐα από θόρυβο. Οι μετρήσεις πραγματοποιήθηκαν με τη βοήθεια ειδικού εξοπλισμού ικανού να παράγει έναν ήχο χαμηλής συχνότητας σε συνδυασμό με ένα tone burst. Με τη βοήθεια των κατάλληλων μηχανημάτων ήταν δυνατή η ανεξάρτητη μεταβολή του πλάτους των δύο ηχητικών ερεθισμάτων, καθώς και της διαφοράς φάσης μεταξύ τους από 0 ως 360 μοίρες. Προσαρμόζοντας τις εντάσεις και τη διαφορά φάσης ο εξεταζόμενος μπορούσε να ακούσει δύο ήχους έναν χαμηλής συχνότητας ως ηχοκάλυψη και έναν υψηλής συχνότητας που ακουγόταν δυνατότερα από την ηχοκάλυψη. Η κύρια παράμετρος που μελετήθηκε ήταν το πλάτος διαμόρφωσης (modulation depth) που είναι η μέγιστη διαφορά μεταξύ του βέλτιστου και του χείριστου ουδού ακοής ενός εξεταζόμενου στο ακοόγραμμα φάσης και μετράται σε dB HL. Αποτελέσματα:Σε φυσιολογικά άτομα η αποτελεσματικότερη ηχοκάλυψη εντοπίστηκε στις 250° και η μικρότερη στις 360°. Λιγότερο αποτελεσματική ήταν η ηχοκάλυψη που παρατηρήθηκε στις 90°. Τα άτομα με φυσιολογική ακοή είχαν πλάτος διαμόρφωσης (modulation depth) μεταξύ 20 και 35 dB HL, οι ασθενείς με βαρηκοΐα αγωγιμότητας παρουσίασαν modulation depth περίπου 10 dB HL και στους ασθενείς με νόσο Ménière μετρήθηκε πλάτος modulation depth σχεδόν 0 dB. Συμπέρασμα: Ο εξοπλισμός και η μέθοδος που αναπτύξαμε πιθανόν να συμβάλλει στη διάγνωση και διαφορική διάγνωση της νόσου Ménière στα πρώιμα στάδια της και στις εξάρσεις που χαρακτηρίζουν την πορεία της. Ο εξοπλισμός που απαιτείται είναι απλός και προσιτός και μπορεί να βρεθεί σε οποιοδήποτε εργαστήριο ιατρικής φυσικής ή μηχανολογίας. Περισσότερες μελέτες είναι αναγκαίες προκειμένου να διερευνηθεί η πιθανή συμβολή της μελέτης του οπισθίου λαβυρίνθου με ηχοκάλυψη χαμηλής συχνότητας στην πρώιμη διάγνωση της νόσου Ménière. / OBJECTIVES: The evaluation of low frequency masking in early diagnosis of Ménière’s Disease (MD). PATIENTS AND METHODS: Thirty-five patients suffered from Ménière’s disease were examined. The results were compared with that of 10 normal hearing ears and 40 noise damaged ears. The examination of all of these individuals was made by the use of a special instrumentation capable to produce a low frequency sound signal superimposed with a tone burst. We were able to independently change the amplitudes of the two applied signals, as well as the phase lag between them from 0° to 360°. Adjusting the two amplitudes and the phase lag the examined individuals heard two sounds one as the masking tone and one high frequency tone superimposed to that of low frequency masking. RESULTS: In normal individuals the highest masking effect was evident at 250° and the lowest at 360°. A smaller masking effect was also evident at 90°. Normal hearing subjects had a modulation depth between 20 and 35 dB, while patients with noise damaged about 10 dB and patients with Ménière’s disease a modulation depth closing to 0 dB. The instrumentation and method presented in this article, shows a relative good clinical diagnostic accuracy as it is capable to diagnose the basilar membrane stiffness on an almost null modulation depth, and sensitivity near 70%. CONCLUSION: The developed instrumentation and method is possible to distinguish and diagnose the early stages of Ménière’s disease and also the acute recurrences. This may lead to a further study of the results of low frequency masking on the anterior labyrinth from research centers worldwide, in order to reinforce the diagnostic accuracy and strength of this newly developed diagnostic method.

The change a speaker makes in response to background noise is known as the Lombard Effect (LE). This study investigated the acoustic changes that are undergone in the presence of broadband noise and two-talker babble. Of particular interest were vocal fundamental frequency (F0) and formant frequency vowel space measures across sex. Forty participants (20 male, 20 female) were recruited and asked to read phrases in quiet and in the presence of two-talker babble and broadband noise. These masker conditions were presented at 50 and 70 dB HL. The phrases were recorded and acoustically analysed. The results showed a significant sex difference for both F0 and vowel space. A masking condition effect was not displayed for either F0 or vowel space. A significant effect was however shown for F0 according to intensity level, suggesting a LE. While the sex difference in F0 values can be explained on the basis of differences in vocal anatomy, the sex difference in vowel space was indicative of a sociophonetic influence on speech production.

Over the years, a variety of array processing techniques have been applied to the problem of enhancing degraded speech to improve automatic speech recognition. In this context, linear beamforming has long been the approach of choice, for reasons including good performance, robustness and analytical simplicity. While various non-linear techniques - typically based to some extent on the study of auditory scene analysis - have also been of interest, they tend to lag behind their linear counterparts in terms of simplicity, scalability and exibility. Nonlinear techniques are also more difficult to analyze and lack the systematic descriptions available in the study of linear beamformers. This work focuses on a class of nonlinear processing, known as time-frequency (T-F) masking - a.k.a. spectro-temporal masking { whose variants comprise a significant portion of the existing techniques. T-F masking is based on accepting or rejecting individual time-frequency cells based on some estimate of local signal quality. Analyses are developed that attempt to mirror the beam patterns used to describe linear processing, leading to a view of T-F masking as "nonlinear beamforming". Two distinct formulations of these "nonlinear beam patterns" are developed, based on different metrics of the algorithms behavior; these formulations are modeled in a variety of scenarios to demonstrate the flexibility of the idea. While these patterns are not quite as simple or all-encompassing as traditional beam patterns in microphone-array processing, they do accurately represent the behavior of masking algorithms in analogous and intuitive ways. In addition to analyzing this class of nonlinear masking algorithm, we also attempt to improve its performance in a variety of ways. Improvements are proposed to the baseline two-channel version of masking, by addressing both the mask estimation and the signal reconstruction stages; the latter more successfully than the former. Furthermore, while these approaches have been shown to outperform linear beamforming in two-sensor arrays, extensions to larger arrays have been few and unsuccessful. We find that combining beamforming and masking is a viable method of bringing the benefits of masking to larger arrays. As a result, a hybrid beamforming-masking approach, called "post-masking", is developed that improves upon the performance of MMSE beamforming (and can be used with any beamforming technique), with the potential for even greater improvement in the future.

abstract: Super-Resolution (SR) techniques are widely developed to increase image resolution by fusing several Low-Resolution (LR) images of the same scene to overcome sensor hardware limitations and reduce media impairments in a cost-effective manner. When choosing a solution for the SR problem, there is always a trade-off between computational efficiency and High-Resolution (HR) image quality. Existing SR approaches suffer from extremely high computational requirements due to the high number of unknowns to be estimated in the solution of the SR inverse problem. This thesis proposes efficient iterative SR techniques based on Visual Attention (VA) and perceptual modeling of the human visual system. In the first part of this thesis, an efficient ATtentive-SELective Perceptual-based (AT-SELP) SR framework is presented, where only a subset of perceptually significant active pixels is selected for processing by the SR algorithm based on a local contrast sensitivity threshold model and a proposed low complexity saliency detector. The proposed saliency detector utilizes a probability of detection rule inspired by concepts of luminance masking and visual attention. The second part of this thesis further enhances on the efficiency of selective SR approaches by presenting an ATtentive (AT) SR framework that is completely driven by VA region detectors. Additionally, different VA techniques that combine several low-level features, such as center-surround differences in intensity and orientation, patch luminance and contrast, bandpass outputs of patch luminance and contrast, and difference of Gaussians of luminance intensity are integrated and analyzed to illustrate the effectiveness of the proposed selective SR frameworks. The proposed AT-SELP SR and AT-SR frameworks proved to be flexible by integrating a Maximum A Posteriori (MAP)-based SR algorithm as well as a fast two-stage Fusion-Restoration (FR) SR estimator. By adopting the proposed selective SR frameworks, simulation results show significant reduction on average in computational complexity with comparable visual quality in terms of quantitative metrics such as PSNR, SNR or MAE gains, and subjective assessment. The third part of this thesis proposes a Perceptually Weighted (WP) SR technique that incorporates unequal weighting parameters in the cost function of iterative SR problems. The proposed approach is inspired by the unequal processing of the Human Visual System (HVS) to different local image features in an image. Simulation results show an enhanced reconstruction quality and faster convergence rates when applied to the MAP-based and FR-based SR schemes. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011

A esquistossomose é uma doença parasitária aguda e crônica causada por vermes sanguíneos (vermes nematoides) do gênero Schistosoma. O homem contrai a esquistossomose através da penetração ativa da cercaria na pele. A importância do tratamento desta enfermidade consiste não só no fato de curar a doença ou diminuir a carga parasitária dos pacientes, bem como impedir sua evolução para formas mais graves. Para o tratamento da esquistossomose o fármaco de escolha é o praziquantel; isso se deve ao seu amplo espectro, sua eficácia, segurança e a relação custo/tratamento. A única forma farmacêutica disponível no Brasil é o comprimido, na dose de 600 mg, a qual pode ser subdividida em quatro partes de 150 mg, a fim de facilitar o ajuste de dose. No entanto, no momento da subdivisão dos comprimidos ocorre o rompimento do revestimento. Este fato acaba levando a uma exposição do fármaco e, consequentemente, de seu sabor amargo. Esta característica dificulta a administração do medicamento, principalmente na população infantil, prejudicando o tratamento e o controle da doença. Uma alternativa para este problema é o desenvolvimento de sistemas poliméricos microparticulados que associados ao fármaco impediriam o contato direto com as papilas gustativas e assim promoveriam uma melhoria na palatabilidade. Para isso utilizou-se a técnica modificada de deposição interfacial do polímero pré-formado seguido de secagem por aspersão. Três matrizes poliméricas, com diferentes características de liberação foram utilizadas, Eudragit RL 100 – liberação tempo dependente e Eudragit E100 e L30D-55 – liberação pH dependente. Além disso, dois tipos de sistemas carreadores do fármaco foram preparados, microcápsulas e microesferas poliméricas. Estes sistemas obtidos foram avaliados e caracterizados a fim de eleger a melhor proposta de formulação visando o mascaramento do sabor do fármaco. De acordo com os resultados obtidos selecionou-se um sistema composto por microcápsulas formadas a partir do polímero L30D-55. A partir de então inseriu-se este sistema na forma farmacêutica pó para suspensão oral, onde diferentes propostas de formulações, contendo dois edulcorantes auxiliares, aspartame e sacarina, separadamente, e seus respectivos placebos foram avaliadas através de um método in vitro para a determinação do sabor, a língua eletrônica ou sensor gustativo. As diferentes formulações avaliadas apresentaram capacidade em mascarar o sabor desagradável do fármaco e, assim resultam em uma promissora alternativa para o aumento da adesão por parte dos pacientes à terapêutica, principalmente para crianças, em virtude da facilidade de administração, do ajuste da dose em função da massa corpórea e ao sabor muito mais agradável ao paladar infantil. / Schistosomiasis is a parasitic disease acute and chronic caused by blood worms (nematodes worms) of the genus Schistosoma. Man acquires schistosomiasis through the active penetration of the worms in skin. The importance of treatment of this disease is not only the fact of curing the disease or decreases the parasite load of patients, well as prevent progression to more severe forms. For the treatment of schistosomiasis praziquantel is the drug of choice, this is due to its wide spectrum, its efficacy, safety and the relation cost / treatment. The single dosage form available in Brazil is tablet at a dose of 600 mg, which can be subdivided into four parts of 150 mg to facilitate dose adjustment. However when the subdivision of the tablets occurs the disruption of the coating. This fact provides a drug exposure and consequently of its bitter taste. This characteristic complicates the administration of the drug mainly in children, affecting the treatment and control of disease. An alternative for this problem is the development of microparticulate polymeric systems which associated with the drug would prevent direct contact with the taste buds and thus promote an improvement in palatability. For this was used a modified technique interfacial deposition of preformed polymer followed by spray drying. Three polymer matrices with different release characteristics have been used, Eudragit RL 100 – time dependent release, and Eudragit E100 and L30D-55 – pH dependent release. Furthermore, two types of drug carrier systems have been prepared, polymeric microspheres and microcapsules. These systems obtained were evaluated and characterized in order to select the best proposal formulation aimed at masking the taste of the drug. According to the results we selected a system comprising microcapsules formed from L30D-55 polymer. From then was inserted into this system in the pharmaceutical form, powder for oral suspension, where different proposals formulations containing two auxiliary sweeteners, aspartame and saccharin, separately, and their respective placebos were evaluated in an in vitro method for determining the taste, the electronic tongue. The different formulations tested presented excellent ability to mask the unpleasant taste of the drug and thus present an excellent alternative for increasing adherence to therapy, especially for children, because of the ease of administration, according on dose adjustment of body mass and the much more palatable to children's taste.

A esquistossomose é uma doença parasitária aguda e crônica causada por vermes sanguíneos (vermes nematoides) do gênero Schistosoma. O homem contrai a esquistossomose através da penetração ativa da cercaria na pele. A importância do tratamento desta enfermidade consiste não só no fato de curar a doença ou diminuir a carga parasitária dos pacientes, bem como impedir sua evolução para formas mais graves. Para o tratamento da esquistossomose o fármaco de escolha é o praziquantel; isso se deve ao seu amplo espectro, sua eficácia, segurança e a relação custo/tratamento. A única forma farmacêutica disponível no Brasil é o comprimido, na dose de 600 mg, a qual pode ser subdividida em quatro partes de 150 mg, a fim de facilitar o ajuste de dose. No entanto, no momento da subdivisão dos comprimidos ocorre o rompimento do revestimento. Este fato acaba levando a uma exposição do fármaco e, consequentemente, de seu sabor amargo. Esta característica dificulta a administração do medicamento, principalmente na população infantil, prejudicando o tratamento e o controle da doença. Uma alternativa para este problema é o desenvolvimento de sistemas poliméricos microparticulados que associados ao fármaco impediriam o contato direto com as papilas gustativas e assim promoveriam uma melhoria na palatabilidade. Para isso utilizou-se a técnica modificada de deposição interfacial do polímero pré-formado seguido de secagem por aspersão. Três matrizes poliméricas, com diferentes características de liberação foram utilizadas, Eudragit RL 100 – liberação tempo dependente e Eudragit E100 e L30D-55 – liberação pH dependente. Além disso, dois tipos de sistemas carreadores do fármaco foram preparados, microcápsulas e microesferas poliméricas. Estes sistemas obtidos foram avaliados e caracterizados a fim de eleger a melhor proposta de formulação visando o mascaramento do sabor do fármaco. De acordo com os resultados obtidos selecionou-se um sistema composto por microcápsulas formadas a partir do polímero L30D-55. A partir de então inseriu-se este sistema na forma farmacêutica pó para suspensão oral, onde diferentes propostas de formulações, contendo dois edulcorantes auxiliares, aspartame e sacarina, separadamente, e seus respectivos placebos foram avaliadas através de um método in vitro para a determinação do sabor, a língua eletrônica ou sensor gustativo. As diferentes formulações avaliadas apresentaram capacidade em mascarar o sabor desagradável do fármaco e, assim resultam em uma promissora alternativa para o aumento da adesão por parte dos pacientes à terapêutica, principalmente para crianças, em virtude da facilidade de administração, do ajuste da dose em função da massa corpórea e ao sabor muito mais agradável ao paladar infantil. / Schistosomiasis is a parasitic disease acute and chronic caused by blood worms (nematodes worms) of the genus Schistosoma. Man acquires schistosomiasis through the active penetration of the worms in skin. The importance of treatment of this disease is not only the fact of curing the disease or decreases the parasite load of patients, well as prevent progression to more severe forms. For the treatment of schistosomiasis praziquantel is the drug of choice, this is due to its wide spectrum, its efficacy, safety and the relation cost / treatment. The single dosage form available in Brazil is tablet at a dose of 600 mg, which can be subdivided into four parts of 150 mg to facilitate dose adjustment. However when the subdivision of the tablets occurs the disruption of the coating. This fact provides a drug exposure and consequently of its bitter taste. This characteristic complicates the administration of the drug mainly in children, affecting the treatment and control of disease. An alternative for this problem is the development of microparticulate polymeric systems which associated with the drug would prevent direct contact with the taste buds and thus promote an improvement in palatability. For this was used a modified technique interfacial deposition of preformed polymer followed by spray drying. Three polymer matrices with different release characteristics have been used, Eudragit RL 100 – time dependent release, and Eudragit E100 and L30D-55 – pH dependent release. Furthermore, two types of drug carrier systems have been prepared, polymeric microspheres and microcapsules. These systems obtained were evaluated and characterized in order to select the best proposal formulation aimed at masking the taste of the drug. According to the results we selected a system comprising microcapsules formed from L30D-55 polymer. From then was inserted into this system in the pharmaceutical form, powder for oral suspension, where different proposals formulations containing two auxiliary sweeteners, aspartame and saccharin, separately, and their respective placebos were evaluated in an in vitro method for determining the taste, the electronic tongue. The different formulations tested presented excellent ability to mask the unpleasant taste of the drug and thus present an excellent alternative for increasing adherence to therapy, especially for children, because of the ease of administration, according on dose adjustment of body mass and the much more palatable to children's taste.

abstract: The unpleasant bitter taste found in many nutritious vegetables may deter people from consuming a healthy diet. We investigated individual differences in taste perception and whether these differences influence the effectiveness of bitterness masking. To test whether phenylthiocarbamide (PTC) `supertasters' also taste salt and sugar with greater intensity, as suggested by Bartoshuk and colleagues (2004), we infused strips of paper with salt water or sugar water. The bitterness rating of the PTC strip had a significant positive linear relationship with ratings of both the intensity of sweet and salt, but the effect sizes were very low, suggesting that the PTC strip does not give a complete picture of tasting ability. Next we investigated whether various seasonings could mask the bitter taste of vegetables and whether this varied with tasting ability. We found that sugar decreased bitterness and lemon decreased liking for vegetables of varying degrees of bitterness. The results did not differ by ability to taste any of the flavors. Therefore, even though there are remarkable individual differences in taste perception, sugar can be used to improve the initial palatability of vegetables and increase their acceptance and consumption. / Dissertation/Thesis / M.A. Psychology 2012

Dans quelle mesure l'expression de nos opinions et nos comportements peuvent être affectés par le caractère public de la situation dans laquelle nous sommes ? Voilà la question qui a guidé ce travail de thèse. Nous plaçant dans la théorie des représentations sociales (RS, Moscovici, 1961) et plus particulièrement dans le cadre des effets de masquage dans l'expression de ces représentations (Guimelli, 1998), nous montrons, par la manipulation du contexte de réponse (public vs. privé), que les pressions normatives qui pèsent sur l'individu peuvent affecter non seulement son expression à propos d'un objet social mais également ses comportements liés à l'objet. De fait, ce travail s'organise autour de deux axes de recherches. Le premier axe, se centrant sur l'expression des RS, souligne, au travers de quatre recherches (n = 952), l'impact du contexte de réponse sur l'expression des individus. On constate que la publicité des réponses, augmentant le niveau de pressions normatives, amène les sujets à mettre en place des stratégies de masquage et d'affichage liées à la désirabilité sociale. Le second axe, s'intéressant à l'impact du contexte public sur les comportements des individus, regroupe deux recherches (n = 371) dans lesquelles on propose aux participants de réaliser la tâche du dilemme itératif du prisonnier. Ces deux recherches mettent en évidence d'une part que les éléments masqués des représentations ont un impact sur les comportements des individus et d'autre part que ces mêmes comportements sont eux aussi dépendants du contexte et plus précisément des enjeux normatifs qui le caractérisent. / To what extent the public aspect of a given situation can influence the expression of our opinions and behaviors is the very question which has been leading this work of thesis. Referring to the theory of social representations (SR, Moscovici, 1961) and more precisely to the concept of masking effects described in the expression of these representations (Guimelli, 1998), we will show that because of the manipulation of the answering context (public vs. private) the normative pressures weighing on an individual can influence, not only his/her expression linked to a social object, but also his/her behaviors connected to this object. Actually this work gets organized around two main lines of research: The first part focuses on the expression of social representations and highlights the impact of the answering context on the expressions used by a group of individuals (study led through four researches n=952). It will be noticed that the public aspect of answers increases the level of normative pressures and therefore brings the subjects to set up masking and displaying strategies which directly results from a social desirability. The second part deals with the impact of the public context on the behavior of individuals (study led through two researches n=371). In this main line, the participants are invited to achieve a task called “the iterative dilemma of the prisoner”. Those two examples will bring to light, one the hand, that masked elements of representations have an impact on the individual behaviors, and on the other hand, that the very same behavior is also dependent of the context and more precisely of the normative characteristics which are at stake.

As data mining increasingly shapes organizational decision-making, the quality of its results must be questioned to ensure trust in the technology. Inaccuracies can mislead decision-makers and cause costly mistakes. With more data collected for analytical purposes, privacy is also a major concern. Data security policies and regulations are increasingly put in place to manage risks, but these policies and regulations often employ technologies that substitute and/or suppress sensitive details contained in the data sets being mined. Data masking and substitution and/or data encryption and suppression of sensitive attributes from data sets can limit access to important details. It is believed that the use of data masking and encryption can impact the quality of data mining results. This dissertation investigated and compared the causal effects of data masking and encryption on classification performance as a measure of the quality of knowledge discovery. A review of the literature found a gap in the body of knowledge, indicating that this problem had not been studied before in an experimental setting. The objective of this dissertation was to gain an understanding of the trade-offs between data security and utility in the field of analytics and data mining. The research used a nationally recognized cancer incidence database, to show how masking and encryption of potentially sensitive demographic attributes such as patients’ marital status, race/ethnicity, origin, and year of birth, could have a statistically significant impact on the patients’ predicted survival. Performance parameters measured by four different classifiers delivered sizable variations in the range of 9% to 10% between a control group, where the select attributes were untouched, and two experimental groups where the attributes were substituted or suppressed to simulate the effects of the data protection techniques. In practice, this represented a corroboration of the potential risk involved when basing medical treatment decisions using data mining applications where attributes in the data sets are masked or encrypted for patient privacy and security concerns.