The effect of reverberation on personal audio devices.

Personal audio refers to the creation of a listening zone within which a person, or a group of people, hears a given sound program, without being annoyed by other sound programs being reproduced in the same space. Generally, these different sound zones are created by arrays of loudspeakers. Although these devices have the capacity to achieve different sound zones in an anechoic environment, they are ultimately used in normal rooms, which are reverberant environments. At high frequencies, reflections from the room surfaces create a diffuse pressure component which is uniform throughout the room volume and thus decreases the directional characteristics of the device. This paper shows how the reverberant performance of an array can be modeled, knowing the anechoic performance of the radiator and the acoustic characteristics of the room. A formulation is presented whose results are compared to practical measurements in reverberant environments. Due to reflections from the room surfaces, pressure variations are introduced in the transfer responses of the array. This aspect is assessed by means of simulations where random noise is added to create uncertainties, and by performing measurements in a real environment. These results show how the robustness of an array is increased when it is designed for use in a reverberant environment.

A superdirective array of phase shift sources.

A superdirective array of audio drivers is described, which is compact compared with the acoustic wavelength over some of its frequency range. In order to minimize the overall sound power output, and hence reduce the excitation of the reverberant field when used in an enclosed space, the individual drivers are made directional by using phase shift enclosures. The motivating application for the array is the enhancement of sound from a television, in a particular region of space, to aid hearing impaired listeners. The design is initially investigated, using free-field simulations, by comparing the performance of 8 monopoles, 8 phase shift loudspeakers, and a double array of 16 monopoles, with a contrast maximization formulation. The construction and testing of an array of 8 drivers is then discussed, together with its measured response in an anechoic environment. The result of using acoustic contrast maximization is then compared with a least squares formulation, which demonstrates that the performance of the least squares solution can be made similar to that given by acoustic contrast maximization in this application, with a suitable choice of the target field.

IBE Promising Strategies Program 2008: "Epilepsy at School: Teaching the Teachers" - educational plan of the "Associação Brasileira de Epilepsia" with teachers of elementary school / Programa IBE Promising Strategies 2008: "Epilepsia nas Escolas: Ensinando os Professores" - plano educacional da Associação Brasileira de Epilepsia com professores de educação básica

INTRODUCTION: The aim of this study is to evaluate trough questionnaires the knowledge about epilepsy of Elementary School teachers obtained in the "Promising Strategies Program 2008" from International Bureau for Epilepsy entitled "Epilepsy at School. Teaching the Teachers." performed by the official Brazilian branch "Associação Brasileira de Epilepsia" (ABE). METHODS: A questionnaire was developed by ABE and it is composed by 35 objective questions concerning the following areas: concepts and definition of epilepsy and its causes (10); treatment and adverse effects of antiepileptic medication (10); popular stigma about epilepsy (5); activities of people with epilepsy (PWE) (5); and finally, first-aid during and after an epileptic seizure (5). The questionnaire was presented in phase (ph) 1 to teachers before the lecture "Epilepsy: Causes, symptoms and treatment" given by a health professional from ABE trough classical live class (CC) or by video-conference (VC) on "Rede do Saber's site" (http://www.rededosaber.sp.gov.br/portais/NotíciasConteúdo/tabid/369/language/pt-BR/IDNoticia/851/Default.aspx) and afterwards in ph 2. The results were compared to a control group of 66 teachers that did not attend any lecture. RESULTS: Classical class was given in four different cities of Brazil and VC was performed in the state of Sao Paulo and was transmitted to 74 different cities, including Sao Paulo city, this latter with 12 sites; 1,153 teachers were instructed either by CC 25 percent (288) or VC 75 percent (865). Most (78.5 percent) were female, aged between 18 to 68 years (mean 41.4); 76.6 percent attended University and 21.1 percent, graduate studies; 50 percent affirmed to know a PWE. The mean of right answers in ph 1 in CC was 78.4 percent (±10.1) and VC, 79.8 percent (±8.6) and in ph 2 in CC, 86.5 percent (±6.4) and VC, 86.8 percent (±7.1), reflecting increased knowledge in ph 2 (p<0.001) in the 2 strategies (control group: ph 1, 78.2 percent±7.4; ph 2, 79.6 percent±8.6; p>0.05). Comparison of variability of the combined action (CC+VC) between ph 1 (79.5 percent±8.6) and 2 (86.8 percent±6.8) was 9.9 percent±13.9 (p<0.001) (control group 2.3 percent±10.2; p<0.001, compared to CC+VC). The topics "popular stigma" and "first aid during seizures" had the lowest correct scores in ph 1 (CC+VC), 74.6 percent and 72.8 percent, respectively (control group 78.8±10.2 and 67.9±17.5). The highest gain (35.6 percent) in ph 2 was observed in "first aid" (control group 0.8±27.2, p<0.001) and the lowest (0.1 percent), in "popular stigma" (control group 1.7±26.4, p>0.05). There was a significant variation in the topic "first aid" in CC, 41.1 percent compared to VC, 33.3 percent (p=0.009). CONCLUSION: The educational plan of the "Associação Brasileira de Epilepsia" revealed good performance of the teachers of Elementary School without significant differences between the types of presentation (CC/VC), although CC was more efficient to teach first aid during epileptic seizures. The topic "Popular stigma about epilepsy knowledge" has not improved after the lectures and this subject still needs further research and efforts for better understanding and action planning.

OBJETIVOS: Avaliar através de questionários o conhecimento obtido pela ação educativa com professores de Educação Básica intitulada "Epilepsia nas Escolas: Ensinando os Professores" no programa "Promising Strategies 2008" do International Bureau for Epilepsy realizado pelo capítulo oficial brasileiro, a Associação Brasileira de Epilepsia (ABE). MÉTODOS: Questionário foi desenvolvido pela ABE com 35 questões objetivas abrangendo os tópicos: conceitos e definições da epilepsia (10); tratamento e reações adversas de medicações antiepilépticas (10); atividades físicas e profissionais da pessoa com epilepsia (PCE) (5); conhecimento popular estigmatizante (5); cuidados básicos durante e após a crise (5). O questionário foi aplicado antes (Fase 1) e depois (Fase 2) da palestra "Epilepsia: Causas, Sintomas e Conduta" por aula presencial (AP) e videoconferência (VC) na "Rede do Saber" (http://www.rededosaber.sp.gov.br/portais/NotíciasConteúdo/tabid/369/language/pt-BR/IDNoticia/851/Default.aspx). Os resultados foram comparados a um grupo controle de 66 professores que não assistiram à aula sobre epilepsia. RESULTADOS: Aula presencial foi ministrada em quatro cidades brasileiras e VC foi transmitida a 74 cidades do estado de São Paulo, incluindo a capital, esta última com 12 sítios de transmissão. Foram instruídos 1.153 educadores por AP 25 por cento (288) e VC 75 por cento (865). A maioria (78,5 por cento) era do sexo feminino, com idades de 18 a 68 anos (média 41,4); 76,6 por cento cursaram ensino superior e 21,1 por cento, pós-graduação; 50 por cento afirmou conhecer PCE. A média de acertos na fase 1 em AP foi de 78,4 por cento (±10,1) e VC, 79,8 por cento (±8,6) e na fase 2 em AP 86,5 por cento (±6,4) e VC, 86,8 por cento (±7,1), refletindo aumento do conhecimento na fase 2 (p<0,001) nas 2 estratégias (grupo controle: fase 1, 78,2 por cento±7.4; fase 2, 79,6 por cento±8.6; p>0,05). A comparação da variação da ação conjunta (AP+VC) entre fase 1 (79,5 por cento,±8,6) e 2 (86,8 por cento,±6,8) foi de 9,9 por cento±13,9 (p<0,001) (grupo controle 2.3 por cento±10.2; p<0,001, comparado a CC+VC). Os tópicos "conhecimento estigmatizante" e "cuidados básicos" tiveram menor índice de acerto na fase 1 (AP+VC), 74,6 por cento e 72,8 por cento, respectivamente (grupo controle 78,8±10,2 e 67,9±17,5). No entanto, o maior ganho (35,6 por cento) na fase 2 se deu em "cuidados básicos" (grupo controle 0,8±27,2, p<0,001) e o menor (0,1 por cento), em "conhecimento estigmatizante" (grupo controle 1,7±26,4, p>0,05). Houve significante variação do tópico "cuidados básicos" em AP 41,1 por cento comparada à VC 33,3 por cento (p=0,009). CONCLUSÃO: A ação educativa da ABE mostrou bom aproveitamento dos educadores sem diferenças significativas entre os modos de divulgação (AP/VC), porém AP foi mais eficiente em ensinar cuidados básicos na crise epiléptica. O tópico "Conhecimento Popular Estigmatizante sobre Epilepsia" não mostrou aumento após a aula, sendo necessários esforços conjuntos em pesquisa e planejamento estratégico nessa área.