{"id":666,"date":"2017-09-03T17:42:24","date_gmt":"2017-09-03T15:42:24","guid":{"rendered":"http:\/\/agora.xtec.cat\/col-carmelites\/?page_id=666"},"modified":"2017-09-04T19:20:15","modified_gmt":"2017-09-04T17:20:15","slug":"decibel","status":"publish","type":"page","link":"https:\/\/agora.xtec.cat\/col-carmelites\/conceptes-tecnics\/decibel\/","title":{"rendered":"Decibel"},"content":{"rendered":"<p>El\u00a0<b>decibel<\/b>\u00a0\u00e9s una unitat\u00a0<a title=\"Logaritme\" href=\"https:\/\/ca.wikipedia.org\/wiki\/Logaritme\">logar\u00edtmica<\/a>\u00a0de mesura que expressa la magnitud d&#8217;una quantitat f\u00edsica (habitualment la\u00a0<a class=\"mw-redirect\" title=\"Pot\u00e8ncia f\u00edsica\" href=\"https:\/\/ca.wikipedia.org\/wiki\/Pot%C3%A8ncia_f%C3%ADsica\">pot\u00e8ncia<\/a>) respecte a un nivell de refer\u00e8ncia. L&#8217;\u00fas d&#8217;una unitat logar\u00edtmica permet representar magnituds molt grans i molt petites amb nombres m\u00e9s petits. En ser una relaci\u00f3 respecte a un nivell de refer\u00e8ncia, el decibel \u00e9s una unitat adimensional.<\/p>\n<p>El decibel \u00e9s comunament utilitzat en\u00a0<a title=\"Ac\u00fastica\" href=\"https:\/\/ca.wikipedia.org\/wiki\/Ac%C3%BAstica\">ac\u00fastica<\/a>\u00a0per a quantificar els nivells de\u00a0<a title=\"So\" href=\"https:\/\/ca.wikipedia.org\/wiki\/So\">so<\/a>\u00a0en relaci\u00f3 a una refer\u00e8ncia de 0\u00a0dB. El nivell de refer\u00e8ncia se sol fixar en el llindar de la percepci\u00f3 humana, i s\u00f3n comuns les comparacions per il\u00b7lustrar els diferents nivells de pressi\u00f3 sonora.<\/p>\n<p>Una ra\u00f3 per utilitzar el decibels \u00e9s que l&#8217;<a title=\"Orella\" href=\"https:\/\/ca.wikipedia.org\/wiki\/Orella\">orella<\/a>\u00a0\u00e9s capa\u00e7 de detectar una molt \u00e0mplia gamma de pressions sonores. La relaci\u00f3 de la pressi\u00f3 ac\u00fastica que causa danys permanents a curt termini limita l&#8217;exposici\u00f3 a la qual una orella sana pot escoltar per sobre d&#8217;un mili\u00f3. Com que el poder en una ona sonora \u00e9s proporcional al quadrat de la pressi\u00f3, la proporci\u00f3 de la pot\u00e8ncia m\u00e0xima a la m\u00ednima pot\u00e8ncia \u00e9s superior a una (breu escala) bilions. Per fer front a una gamma tan \u00e0mplia, les unitats logar\u00edtmiques s\u00f3n \u00fatils: el registre d&#8217;un bili\u00f3 de \u00e9s de 12, per la qual cosa aquesta relaci\u00f3 representa una difer\u00e8ncia de 120\u00a0dB. At\u00e8s que l&#8217;orella humana no \u00e9s igualment sensible a totes les freq\u00fc\u00e8ncies de so dins de tot l&#8217;espectre, els nivells de soroll a m\u00e0xima sensibilitat humana &#8211; per exemple, els harm\u00f2nics superiors d&#8217;una mitjana (entre 2 i 4\u00a0kHz) &#8211; s\u00f3n un factor molt m\u00e9s s\u00f2lid en les descripcions usant un proc\u00e9s anomenat de ponderaci\u00f3 de\u00a0<a title=\"Freq\u00fc\u00e8ncia\" href=\"https:\/\/ca.wikipedia.org\/wiki\/Freq%C3%BC%C3%A8ncia\">freq\u00fc\u00e8ncia<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>El\u00a0decibel\u00a0\u00e9s una unitat\u00a0<a title=\"Logaritme\" href=\"https:\/\/ca.wikipedia.org\/wiki\/Logaritme\">logar\u00edtmica<\/a>\u00a0de mesura que expressa la magnitud d&#8217;una quantitat f\u00edsica (habitualment la\u00a0<a class=\"mw-redirect\" title=\"Pot\u00e8ncia f\u00edsica\" href=\"https:\/\/ca.wikipedia.org\/wiki\/Pot%C3%A8ncia_f%C3%ADsica\">pot\u00e8ncia<\/a>) respecte a un nivell de refer\u00e8ncia. L&#8217;\u00fas d&#8217;una unitat logar\u00edtmica permet representar magnituds molt grans i molt petites amb nombres m\u00e9s petits. En ser una relaci\u00f3&hellip;  <a href=\"https:\/\/agora.xtec.cat\/col-carmelites\/conceptes-tecnics\/decibel\/\" title=\"Read Decibel\">Llegeix m\u00e9s\u00bb<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":652,"menu_order":30,"comment_status":"closed","ping_status":"closed","template":"page-templates\/side-menu.php","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"footnotes":""},"class_list":["post-666","page","type-page","status-publish","hentry"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/pages\/666","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/comments?post=666"}],"version-history":[{"count":1,"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/pages\/666\/revisions"}],"predecessor-version":[{"id":667,"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/pages\/666\/revisions\/667"}],"up":[{"embeddable":true,"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/pages\/652"}],"wp:attachment":[{"href":"https:\/\/agora.xtec.cat\/col-carmelites\/wp-json\/wp\/v2\/media?parent=666"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}