Hearing impairment is the number one chronic disability affecting people in the world. Many people have great difficulty in understanding speech with background noise. This is especially true for a large number of elderly people and the sensorineural impaired persons. Several investigations on speech intelligibility have demonstrated that subjects with sensorineural loss may need a 5-15 dB higher signal-to-noise ratio than the normal hearing subjects. While most defects in transmission chain up to cochlea can nowadays be successfully rehabilitated by means of surgery, the great majority of the remaining inoperable cases are sensorineural hearing impaired, Recent statistics of the hearing impaired patients applying for a hearing aid reveal that 20% of the cases are due to conductive losses, more than 50% are due to sensorineural losses, and the rest 30% of the cases are of mixed origin. Presenting speech to the hearing impaired in an intelligible form remains a major challenge in hearing-aid research today. Even-though various methods have been suggested in the literature for the minimization of noise from the contaminated speech signals, they fail to give good SNR improvement and intelligibility improvement for moderate to-severe sensorineural loss subjects. So far, the power and capability of Newton's method, Nonlinear adaptive filtering methods and the feedback type artificial neural networks have not been exploited for this purpose. Hence we resort to the application of all these methods for improving SNR and intelligibility for the sensorineural loss subjects. Digital hearing aids frequently employ the concept of filter banks. One of the major drawbacks of this techniques is the complexity of computation requiring more number of multiplications. This increases the power consumption. Therefore this Thesis presents the new approach to speech enhancement for the hearing impaired and also the construction of filter bank in Digital hearing aid with minimum number of multiplications. The following are covered in this thesis. One of the most important application of adaptive systems is in noise cancellation using adaptive filters. The ANC setup requires two input signals (viz., primary and reference). The primary input consists of the sum of the desired signal and noise which is uncorrelated. The reference input consists of mother noise which is correlated in Some unknown way with noise of primary input. The primary signal is obtained by placing the omnidirectional microphone just above one ear on the head of the KEMAR mannikan and the reference signal is obtained by placing the hypercardioid microphone at the center of the vertebral column on the back. Conventional speech enhancement techniques use linear schemes for enhancing speech signals. So far Nonlinear adaptive filtering techniques are not used in hearing aid applications. The motivation behind the use of nonlinear model is that it gives better noise suppression as compared to linear model. This is because the medium through which signals reach the microphone may be highly nonlinear. Hence the use of linear schemes, though motivated by computational simplicity and mathematical tractability, may be suboptimal. Hence, we propose the use of nonlinear models to enhance the speech signals for the hearing impaired: We propose both Linear LMS and Nonlinear second order Volterra LMS schemes to enhance speech signals. Studies conducted for different environmental noise including babble, cafeteria and low frequency noise show that the second-order Volterra LMS performs better compared to linear LMS algorithm. We use measures such as signal-to-noise ratio (SNR), time plots, and intelligibility tests for performance comparison. We also propose an ANC scheme which uses Newton's method to enhance speech signals. The main problem associated with LMS based ANC is that their convergence is slow and hence their performance becomes poor for hearing aid applications. The reason for choosing Newton's method is that they have high performance adaptive-filtering methods that often converge and track faster than LMS method. We propose two models to enhance speech signals: one is conventional linear model and the other is a nonlinear model using a second order Volterra function. Development of Newton's type algorithm for linear mdel results in familiar Recursive least square (RLS) algorithm. The performance of both linear and non-linear Newton's algorithm is evaluated for babble, cafeteria and frequency noise. SNR, timeplots and intelligibility tests are used for performance comparison. The results show that Newton's method using Volterra nonlinearity performs better than RLS method. ln addition to the ANC based schemes, we also develop speech enhancement for the hearing impaired by using the feedback type neural network (FBNN). The main reason is that here we have parallel algorithm which can be implemented directly in hardware. We translate the speech enhancement problem into a neural network (NN) framework by forming an appropriate energy function. We propose both linear and nonlinear FBNN for enhancing the speech signals. Simulated studies on different environmental noise reveal that the FBNN using the Volterra nonlinearity is superior to linear FBNN in enhancing speech signals. We use SNR, time plots, and intelligibility tests for performance comparison. The design of an effective hearing aid is a challenging problem for sensorineural hearing impaired people. For persons with sensorineural losses it is necessary that the frequency response should be optimally fitted into their residual auditory area. Digital filter enhances the performance of the hearing aids which are either difficult or impossible to realize using analog techniques. The major problem in digital hearing aid is that of reducing power consumption. Multiplication is one of the most power consuming operation in digital filtering. Hence a serious effort has been made to design filter bank with minimum number of multiplications, there by minimizing the power consumption. It is achieved by using Interpolated and complementary FIR filters. This method gives significant savings in the number of arithmetic operations. The Thesis is concluded by summarizing the results of analysis, and suggesting scope for further investigation

A International Federation of Oto-Rhino-Laryngological Societes (IFOS) estima que cerca de 10% da população americana seja portadora de algum tipo de perda auditiva. O Better Hearing Institute afirma que nos Estados Unidos cerca de 31 milhões de pessoas apresentam algum tipo de perda auditiva, ou cerca de 10% de sua população. Muitas são as causas que contribuem para o aumento do contingente de deficientes auditivos, dentre os quais a presbiacusia, as doenças hereditárias, doenças metabólicas, uso de drogas ototóxicas, traumas acústicos, excesso de ruído, neoplasias, infecções e danos vasculares e causas idiopáticas. Dentre os efeitos perniciosos da perda auditiva estão a frustração, insegurança, paranóia, tensão, nervosismo, irritabilidade, instabilidade, medo, sensação de inferioridade, sensação de confusão, descontentamento, fobia social e depressão. Crianças com perdas auditivas unilaterais tendem a apresentar baixos níveis de aproveitamentos escolares, a demandar por técnicas especiais de linguagem por conta dos efeitos permanentes da incapacidade de cognição, mesmo quando se tratava de perdas auditivas leves. Pelo prisma da audiologia clínica todo portador de deficiência auditiva pode ser considerado um candidato ao uso de prótese auditiva - ou aparelho auditivo - um dispositivo eletrônico cujos componentes principais - processador digital de sinais, microfone e receptor - podem ser adquiridos da cadeia de suprimentos que abastecem os fabricantes internacionais que dominam o mercado mundial. Estes fabricantes procuram ofertar produtos com uma maior densidade de recursos tecnológicos que os seus concorrentes em paga de lucros maiores, a oferecer mais que os clientes necessitam ou estão dispostos a pagar. Estas organizações internacionais trazem produtos cujos preços finais são incompatíveis para os cidadãos de países em desenvolvimento. Um dos objetivos deste estudo é o de entender o modelo de negócios praticado pela indústria de próteses auditivas, notavelmente a prática de varejo, a mais lucrativa. O outro objetivo é o de desenvolver uma prótese auditiva no desenho retroauricular, digital e de especificações mínimas, que possa competir com aquelas fornecidas por organizações lv internacionais para a condução das políticas públicas, segundo a Portaria 587, Anexo IV do Ministério da Saúde. Foi contatada a cadeia de suprimentos destas organizações, solicitadas amostras diversas e montados protótipos funcionais, que depois de vários ensaios permitiram a definição de uma arquitetura eletroeletrônica básica. Esta arquitetura foi novamente ensaiada, tendo como resultado um configuração eletroeletrônica final, a qual definiu uma prótese no desenho retroauricular. De modo a definir os recursos tecnológicos e as especificações eletroacústicas do produto final para o atendimento das especificações do Ministério da Saúde, foram utilizadas as ferramentas de engenharia do fabricante do componente principal (processador digital de sinais), que incluíam o desenvolvimento com base no servidor do fabricante (online), desenvolvimento com auxílio de programas específicos (stand alone), montagem eletroeletrônica e mecânica para finalmente certificar o produto final com a mesma norma internacional das próteses auditivas comercializadas no mercado nacional. Foi possível entender o modelo de negócios praticado na indústria de próteses auditivas com a identificação dos principais atores e como se relacionam. A única prótese auditiva desenvolvida no desenho retroauricular atende a todos os requisitos de Tecnologia A e B, o que corresponde a 85% da demanda das aquisições do Governo Federal. / The International Federation of Oto-Rhino-Laryngological Societies (IFOS) estimates as 10% the total amount of hearing impaired in United States. The Better Hearing Institute asserts that in United States about 31 million people have hearing losses in some degree, say around 10% of total population. Increasing the amount of hearing-impaired there is a list of causes as presbyacusis, hereditary diseases, metabolic diseases, use of ototoxic drugs, acoustic trauma, noise-induced, neoplasia, infections and vascular damages and idiopathic causes. Amongst of perverse effects of hearing losses are frustration, insecurity, paranoia, tension, nervousness, irritability, instability, fearful, sense of inferiority, sense of confusion, discontentment, social phobia and depression. Children with unilateral hearing loss appear to show high grade failures, demands for additional assistance due to permanent effects of cognition inability, even so when they are affected by mild hearing losses. By means of Audiology perspective all hearing impaired are normal applicant to wear a hearing aid, an electronic device whose chief components - digital signal processing, microphone and receiver - can be acquired from the international manufacturers supply chain, whose rule the world market. These manufacturers push products to market with higher density of technological resources than their competitors in exchange of higher profits, to offer more than the customers need or are willing to pay for. Those international organizations bring products which end prices are unmatched to citizen in the developing countries. One of the objectives of the present study is to understand the business model these organizations run, mainly the most profitable one: retail business. The other objective means the developing the digital behind-the-ear hearing aid with minimal specifications, to compete with those hearing aids, same design, supplied by these organizations to the Brazilian Government for its open tender, according to Government directive 587, section sign IV of Health Minister. It was contacted these organizations supply chain, requested samples and assembled some functional prototypes, whose after some experiments lead us to determine a basic electroelectronic architecture. This architecture was submitted to more experiments until final lvii electroelectronic architecture was determined and it was rested inside a behind-the-ear case. To determine end product technological resources and the electroacoustic specifications to fulfill Health Minister specifications it was managed engineering tools of the main component (digital signal processing), which entails being logon on the manufacturer server, also stand alone on a personal computer, to assemble the electro-electronic and mechanical modules to submit the end product to the same international standard the hearing aids already traded in the Brazilian market place. It was possible the understanding the current business model also to identify the main actors and how they interact each other. The only digital behind-the-ear hearing aid developed complies with all requirements labeled as Technology A and B, respective of 85% of all Brazilian Government acquisitions.

A International Federation of Oto-Rhino-Laryngological Societes (IFOS) estima que cerca de 10% da população americana seja portadora de algum tipo de perda auditiva. O Better Hearing Institute afirma que nos Estados Unidos cerca de 31 milhões de pessoas apresentam algum tipo de perda auditiva, ou cerca de 10% de sua população. Muitas são as causas que contribuem para o aumento do contingente de deficientes auditivos, dentre os quais a presbiacusia, as doenças hereditárias, doenças metabólicas, uso de drogas ototóxicas, traumas acústicos, excesso de ruído, neoplasias, infecções e danos vasculares e causas idiopáticas. Dentre os efeitos perniciosos da perda auditiva estão a frustração, insegurança, paranóia, tensão, nervosismo, irritabilidade, instabilidade, medo, sensação de inferioridade, sensação de confusão, descontentamento, fobia social e depressão. Crianças com perdas auditivas unilaterais tendem a apresentar baixos níveis de aproveitamentos escolares, a demandar por técnicas especiais de linguagem por conta dos efeitos permanentes da incapacidade de cognição, mesmo quando se tratava de perdas auditivas leves. Pelo prisma da audiologia clínica todo portador de deficiência auditiva pode ser considerado um candidato ao uso de prótese auditiva - ou aparelho auditivo - um dispositivo eletrônico cujos componentes principais - processador digital de sinais, microfone e receptor - podem ser adquiridos da cadeia de suprimentos que abastecem os fabricantes internacionais que dominam o mercado mundial. Estes fabricantes procuram ofertar produtos com uma maior densidade de recursos tecnológicos que os seus concorrentes em paga de lucros maiores, a oferecer mais que os clientes necessitam ou estão dispostos a pagar. Estas organizações internacionais trazem produtos cujos preços finais são incompatíveis para os cidadãos de países em desenvolvimento. Um dos objetivos deste estudo é o de entender o modelo de negócios praticado pela indústria de próteses auditivas, notavelmente a prática de varejo, a mais lucrativa. O outro objetivo é o de desenvolver uma prótese auditiva no desenho retroauricular, digital e de especificações mínimas, que possa competir com aquelas fornecidas por organizações lv internacionais para a condução das políticas públicas, segundo a Portaria 587, Anexo IV do Ministério da Saúde. Foi contatada a cadeia de suprimentos destas organizações, solicitadas amostras diversas e montados protótipos funcionais, que depois de vários ensaios permitiram a definição de uma arquitetura eletroeletrônica básica. Esta arquitetura foi novamente ensaiada, tendo como resultado um configuração eletroeletrônica final, a qual definiu uma prótese no desenho retroauricular. De modo a definir os recursos tecnológicos e as especificações eletroacústicas do produto final para o atendimento das especificações do Ministério da Saúde, foram utilizadas as ferramentas de engenharia do fabricante do componente principal (processador digital de sinais), que incluíam o desenvolvimento com base no servidor do fabricante (online), desenvolvimento com auxílio de programas específicos (stand alone), montagem eletroeletrônica e mecânica para finalmente certificar o produto final com a mesma norma internacional das próteses auditivas comercializadas no mercado nacional. Foi possível entender o modelo de negócios praticado na indústria de próteses auditivas com a identificação dos principais atores e como se relacionam. A única prótese auditiva desenvolvida no desenho retroauricular atende a todos os requisitos de Tecnologia A e B, o que corresponde a 85% da demanda das aquisições do Governo Federal. / The International Federation of Oto-Rhino-Laryngological Societies (IFOS) estimates as 10% the total amount of hearing impaired in United States. The Better Hearing Institute asserts that in United States about 31 million people have hearing losses in some degree, say around 10% of total population. Increasing the amount of hearing-impaired there is a list of causes as presbyacusis, hereditary diseases, metabolic diseases, use of ototoxic drugs, acoustic trauma, noise-induced, neoplasia, infections and vascular damages and idiopathic causes. Amongst of perverse effects of hearing losses are frustration, insecurity, paranoia, tension, nervousness, irritability, instability, fearful, sense of inferiority, sense of confusion, discontentment, social phobia and depression. Children with unilateral hearing loss appear to show high grade failures, demands for additional assistance due to permanent effects of cognition inability, even so when they are affected by mild hearing losses. By means of Audiology perspective all hearing impaired are normal applicant to wear a hearing aid, an electronic device whose chief components - digital signal processing, microphone and receiver - can be acquired from the international manufacturers supply chain, whose rule the world market. These manufacturers push products to market with higher density of technological resources than their competitors in exchange of higher profits, to offer more than the customers need or are willing to pay for. Those international organizations bring products which end prices are unmatched to citizen in the developing countries. One of the objectives of the present study is to understand the business model these organizations run, mainly the most profitable one: retail business. The other objective means the developing the digital behind-the-ear hearing aid with minimal specifications, to compete with those hearing aids, same design, supplied by these organizations to the Brazilian Government for its open tender, according to Government directive 587, section sign IV of Health Minister. It was contacted these organizations supply chain, requested samples and assembled some functional prototypes, whose after some experiments lead us to determine a basic electroelectronic architecture. This architecture was submitted to more experiments until final lvii electroelectronic architecture was determined and it was rested inside a behind-the-ear case. To determine end product technological resources and the electroacoustic specifications to fulfill Health Minister specifications it was managed engineering tools of the main component (digital signal processing), which entails being logon on the manufacturer server, also stand alone on a personal computer, to assemble the electro-electronic and mechanical modules to submit the end product to the same international standard the hearing aids already traded in the Brazilian market place. It was possible the understanding the current business model also to identify the main actors and how they interact each other. The only digital behind-the-ear hearing aid developed complies with all requirements labeled as Technology A and B, respective of 85% of all Brazilian Government acquisitions.