Avaliação Subjetiva do Ruído
Autor | Tuffi Messias Saliba |
Ocupação do Autor | Engenheiro Mecânico |
Páginas | 19-23 |
Page 19
Como visto anteriormente, a Lei de Weber-Fechner mostra que o aumento da sensação ao som é proporcional ao logaritmo do estímulo. Todavia, em razão do complexo mecanismo da audição, essa relação é apenas uma aproximação, pois outros fatores influenciam na percepção do som, especialmente a frequência.
Fechner, em companhia de Munson, conseguiu, em 1933, estabelecer uma série de curvas em espaço métrico de nível de pressão sonora contra frequência, onde era demonstrada a variação dessa sensação de força relativa à frequência. Foi observado que os tons mais baixos ou graves requerem mais energia do que os tons médios para serem escutados com a mesma força, e que estes, por sua vez, requeriam menos energia que os muito altos ou agudos (ALEXANDRY, 1978). Portanto, a audição humana não tem sensação igual em todas as frequências.
Com base nesse estudo, partindo-se de um padrão (frequência de
1.000 Hz), foi medida a resposta subjetiva produzida por determinado NPS em cada frequência e, com base nesses dados, foram traçadas as curvas isoaudíveis. Essas curvas foram revisadas em 1956 por Robinson e Dadson e foram adotadas pela recomendação ISO 226. Em estudo recente, a ISO redefiniu nova curva na norma ISO 226:2003. A seguir, a figura 1 mostra as curvas isoaudíveis ou de audibilidade.
Page 20
Observa-se na Figura 1 que a sensibilidade do ouvido é menor nas baixas frequências e maior nas altas. Observa-se também que a faixa de maior sensibilidade, nas curvas de Robinson e Dadson, é a partir de 4.000 Hz. As curvas isoaudíveis representam a mesma intensidade de resposta ao ouvido a determinados sons. Assim, por exemplo, um som de NA (Nível de Audibilidade) de 90 sons é sentido com a mesma intensidade pela maioria das pessoas, quaisquer que sejam a frequência e o NPS.
Ocorre que, muitas vezes, para produzir a mesma audibilidade, são necessários diferentes níveis de pressão sonora, quando estes estão em diferentes frequências, pois o ouvido humano sente o ruído de forma diferente nas diversas frequências. Assim, por exemplo, um NA (nível de audibilidade) de 90 fons, na frequência de 4.000 Hz, é produzido por um NPS de 80 dB (ver figura 1). Na frequência de 125 Hz, esse som é ouvido com a mesma intensidade, porém, produzido por NPS de 85 dB. Portanto, observa-se que na frequência de 4.000 Hz é necessário um NPS menor para...
Para continuar a ler
PEÇA SUA AVALIAÇÃOSubscribers can access the reported version of this case.
You can sign up for a trial and make the most of our service including these benefits.
Por que se inscrever na vLex?
-
Over 100 Countries
Search over 120 million documents from over 100 countries including primary and secondary collections of legislation, case law, regulations, practical law, news, forms and contracts, books, journals, and more.
-
Thousands of Data Sources
Updated daily, vLex brings together legal information from over 750 publishing partners, providing access to over 2,500 legal and news sources from the world’s leading publishers.
-
Find What You Need, Quickly
Advanced A.I. technology developed exclusively by vLex editorially enriches legal information to make it accessible, with instant translation into 14 languages for enhanced discoverability and comparative research.
-
Over 2 million registered users
Founded over 20 years ago, vLex provides a first-class and comprehensive service for lawyers, law firms, government departments, and law schools around the world.
Subscribers are able to see a list of all the cited cases and legislation of a document.
You can sign up for a trial and make the most of our service including these benefits.
Por que se inscrever na vLex?
-
Over 100 Countries
Search over 120 million documents from over 100 countries including primary and secondary collections of legislation, case law, regulations, practical law, news, forms and contracts, books, journals, and more.
-
Thousands of Data Sources
Updated daily, vLex brings together legal information from over 750 publishing partners, providing access to over 2,500 legal and news sources from the world’s leading publishers.
-
Find What You Need, Quickly
Advanced A.I. technology developed exclusively by vLex editorially enriches legal information to make it accessible, with instant translation into 14 languages for enhanced discoverability and comparative research.
-
Over 2 million registered users
Founded over 20 years ago, vLex provides a first-class and comprehensive service for lawyers, law firms, government departments, and law schools around the world.
Subscribers are able to see a list of all the documents that have cited the case.
You can sign up for a trial and make the most of our service including these benefits.
Por que se inscrever na vLex?
-
Over 100 Countries
Search over 120 million documents from over 100 countries including primary and secondary collections of legislation, case law, regulations, practical law, news, forms and contracts, books, journals, and more.
-
Thousands of Data Sources
Updated daily, vLex brings together legal information from over 750 publishing partners, providing access to over 2,500 legal and news sources from the world’s leading publishers.
-
Find What You Need, Quickly
Advanced A.I. technology developed exclusively by vLex editorially enriches legal information to make it accessible, with instant translation into 14 languages for enhanced discoverability and comparative research.
-
Over 2 million registered users
Founded over 20 years ago, vLex provides a first-class and comprehensive service for lawyers, law firms, government departments, and law schools around the world.
Os assinantes podem ver as versões revisadas da legislação com emendas
You can sign up for a trial and make the most of our service including these benefits.
Por que se inscrever na vLex?
-
Over 100 Countries
Search over 120 million documents from over 100 countries including primary and secondary collections of legislation, case law, regulations, practical law, news, forms and contracts, books, journals, and more.
-
Thousands of Data Sources
Updated daily, vLex brings together legal information from over 750 publishing partners, providing access to over 2,500 legal and news sources from the world’s leading publishers.
-
Find What You Need, Quickly
Advanced A.I. technology developed exclusively by vLex editorially enriches legal information to make it accessible, with instant translation into 14 languages for enhanced discoverability and comparative research.
-
Over 2 million registered users
Founded over 20 years ago, vLex provides a first-class and comprehensive service for lawyers, law firms, government departments, and law schools around the world.
Subscribers are able to see any amendments made to the case.
You can sign up for a trial and make the most of our service including these benefits.
Por que se inscrever na vLex?
-
Over 100 Countries
Search over 120 million documents from over 100 countries including primary and secondary collections of legislation, case law, regulations, practical law, news, forms and contracts, books, journals, and more.
-
Thousands of Data Sources
Updated daily, vLex brings together legal information from over 750 publishing partners, providing access to over 2,500 legal and news sources from the world’s leading publishers.
-
Find What You Need, Quickly
Advanced A.I. technology developed exclusively by vLex editorially enriches legal information to make it accessible, with instant translation into 14 languages for enhanced discoverability and comparative research.
-
Over 2 million registered users
Founded over 20 years ago, vLex provides a first-class and comprehensive service for lawyers, law firms, government departments, and law schools around the world.
Subscribers are able to see a visualisation of a case and its relationships to other cases. An alternative to lists of cases, the Precedent Map makes it easier to establish which ones may be of most relevance to your research and prioritise further reading. You also get a useful overview of how the case was received.
Por que se inscrever na vLex?
-
Over 100 Countries
Search over 120 million documents from over 100 countries including primary and secondary collections of legislation, case law, regulations, practical law, news, forms and contracts, books, journals, and more.
-
Thousands of Data Sources
Updated daily, vLex brings together legal information from over 750 publishing partners, providing access to over 2,500 legal and news sources from the world’s leading publishers.
-
Find What You Need, Quickly
Advanced A.I. technology developed exclusively by vLex editorially enriches legal information to make it accessible, with instant translation into 14 languages for enhanced discoverability and comparative research.
-
Over 2 million registered users
Founded over 20 years ago, vLex provides a first-class and comprehensive service for lawyers, law firms, government departments, and law schools around the world.
Subscribers are able to see the list of results connected to your document through the topics and citations Vincent found.
You can sign up for a trial and make the most of our service including these benefits.
Por que se inscrever na vLex?
-
Over 100 Countries
Search over 120 million documents from over 100 countries including primary and secondary collections of legislation, case law, regulations, practical law, news, forms and contracts, books, journals, and more.
-
Thousands of Data Sources
Updated daily, vLex brings together legal information from over 750 publishing partners, providing access to over 2,500 legal and news sources from the world’s leading publishers.
-
Find What You Need, Quickly
Advanced A.I. technology developed exclusively by vLex editorially enriches legal information to make it accessible, with instant translation into 14 languages for enhanced discoverability and comparative research.
-
Over 2 million registered users
Founded over 20 years ago, vLex provides a first-class and comprehensive service for lawyers, law firms, government departments, and law schools around the world.