{"id":100168,"date":"2026-02-15T20:22:05","date_gmt":"2026-02-15T20:22:05","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100168"},"modified":"2026-04-05T15:39:13","modified_gmt":"2026-04-05T15:39:13","slug":"noise-distance-attenuation","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/bn\/calculators\/noise-distance-attenuation\/","title":{"rendered":"Noise Distance Attenuation Calculator | Free SPL Tool"},"content":{"rendered":"\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Noise Distance Attenuation Calculator\",\"description\":\"Calculate sound level at any distance using the inverse square law.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/noise-distance-attenuation\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2024-01-01\",\"dateModified\":\"2025-02-14\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true}<\/script>\n\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"How does sound level decrease with distance?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"For a point source in free field, sound pressure level decreases by 6 dB for each doubling of distance from the source (inverse square law).\"}},\n{\"@type\":\"Question\",\"name\":\"What is the inverse square law for sound?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"L2 = L1 \u2212 20\u00b7log10(d2\/d1). This means SPL drops proportionally to the square of the distance ratio.\"}},\n{\"@type\":\"Question\",\"name\":\"Does this formula work indoors?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"It applies in the direct field only. Indoors, reflections create a reverberant field where level stays roughly constant beyond a certain distance.\"}},\n{\"@type\":\"Question\",\"name\":\"What about line sources like roads?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Line sources follow L2 = L1 \u2212 10\u00b7log10(d2\/d1), giving only 3 dB reduction per doubling of distance, not 6 dB.\"}},\n{\"@type\":\"Question\",\"name\":\"How far to reduce 90 dB to 70 dB?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"You need a 20 dB reduction = 10\u00d7 the reference distance. If 90 dB at 1 m, you need 10 m to reach 70 dB (free field, point source).\"}}\n]}<\/script>\n\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Noise Distance Attenuation\",\"item\":\"https:\/\/vibromera.eu\/calculators\/noise-distance-attenuation\/\"}]}<\/script>\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n\n<link 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.15s}.vc-faq-q:hover{background:#ede9e3}.vc-faq-chevron{width:16px;height:16px;color:var(--vc-ink-muted);flex-shrink:0;transition:transform .25s}.vc-faq-item.vc-open .vc-faq-chevron{transform:rotate(180deg)}.vc-faq-a{max-height:0;overflow:hidden;transition:max-height .35s}.vc-faq-item.vc-open .vc-faq-a{max-height:1200px}.vc-faq-a-inner{padding:14px 16px;border-top:1px solid var(--vc-border-light);font-size:14px;color:var(--vc-ink-secondary)}.vc-faq-a-inner p{margin:0 0 8px}.vc-faq-a-inner p:last-child{margin-bottom:0}.vc-related{display:flex;flex-wrap:wrap;gap:10px;margin-top:16px}.vc-related-link{display:inline-block;padding:8px 16px;font-family:var(--vc-font);font-size:13px;font-weight:600;background:var(--vc-surface-alt);color:var(--vc-ink-secondary);border:1px solid var(--vc-border);border-radius:var(--vc-radius);text-decoration:none;transition:all .15s}.vc-related-link:hover{border-color:var(--vc-accent);color:var(--vc-accent);background:var(--vc-accent-light)}.vc-promo{margin-top:24px;padding:20px;background:linear-gradient(135deg,var(--vc-accent-light),var(--vc-surface));border:1px solid var(--vc-border);border-radius:var(--vc-radius-lg);display:flex;align-items:center;gap:16px}.vc-promo-text{flex:1;font-size:14px;color:var(--vc-ink-secondary)}.vc-promo-text strong{color:var(--vc-ink)}.vc-promo-link{padding:8px 20px;font-size:13px;font-weight:700;color:#fff;background:var(--vc-accent);border-radius:var(--vc-radius);text-decoration:none;white-space:nowrap;transition:background .15s}.vc-promo-link:hover{background:var(--vc-accent-hover)}.vc-footer{text-align:center;padding:32px 16px;font-size:13px;color:var(--vc-ink-muted)}.vc-footer a{color:var(--vc-accent);text-decoration:none}.vc-footer a:hover{text-decoration:underline}.vc-footer-links{margin-top:8px;font-size:12px}.vc-footer-links a{margin:0 8px}@media print{.vc-section-body{max-height:none!important}.vc-faq-a{max-height:none!important}.vc-results{max-height:none!important;padding:24px!important}.vc-copy-btn,.vc-section-chevron,.vc-faq-chevron,.vc-presets,.vc-promo{display:none!important}}\n<\/style>\n\n<div class=\"vc-calculator\">\n<header class=\"vc-header\">\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool #215<\/p>\n    <h1 class=\"vc-header-title\">Noise Distance Attenuation Calculator<\/h1>\n    <p class=\"vc-header-subtitle\">Calculate sound pressure level at any distance from a point source. Uses the inverse square law for free-field propagation.<\/p>\n    <div class=\"vc-badges\"><span class=\"vc-badge\">L\u2082 = L\u2081 \u2212 20\u00b7log\u2081\u2080(d\u2082\/d\u2081)<\/span><span class=\"vc-badge\">Point Source<\/span><span class=\"vc-badge\">Free Field<\/span><\/div>\n<\/header>\n<div class=\"vc-card\">\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\n        <div class=\"vc-form-grid\">\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-l1\">Reference Level (L\u2081) <span class=\"vc-label-hint\">(dB\/dBA)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-l1\" step=\"any\" placeholder=\"e.g. 90\" value=\"90\"><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-d1\">Reference Distance (d\u2081) <span class=\"vc-label-hint\">(m)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-d1\" step=\"any\" min=\"0.01\" placeholder=\"e.g. 1\" value=\"1\"><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-d2\">Target Distance (d\u2082) <span class=\"vc-label-hint\">(m)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-d2\" step=\"any\" min=\"0.01\" placeholder=\"e.g. 10\" value=\"10\"><\/div>\n        <\/div>\n        <div class=\"vc-presets\">\n            <div class=\"vc-presets-label\">Quick presets<\/div>\n            <button type=\"button\" class=\"vc-preset-btn\" data-l=\"90\" data-d1=\"1\" data-d2=\"5\">90 dB @ 1m \u2192 5m<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-l=\"100\" data-d1=\"1\" data-d2=\"10\">100 dB @ 1m \u2192 10m<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-l=\"85\" data-d1=\"1\" data-d2=\"50\">85 dB @ 1m \u2192 50m<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-l=\"95\" data-d1=\"2\" data-d2=\"20\">95 dB @ 2m \u2192 20m<\/button>\n        <\/div>\n    <\/form>\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\"><h2 class=\"vc-results-title\">Results<\/h2><button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\"><svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy<\/button><\/div>\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\"><div class=\"vc-rcard-label\">Level at Target Distance (L\u2082)<\/div><div class=\"vc-rcard-value\" id=\"vc-r-l2\">\u2014<\/div><\/div>\n            <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Attenuation<\/div><div class=\"vc-rcard-value\" id=\"vc-r-atten\">\u2014<\/div><\/div>\n            <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Distance Ratio<\/div><div class=\"vc-rcard-value\" id=\"vc-r-ratio\">\u2014<\/div><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-section vc-open\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udcd8<\/span><span class=\"vc-section-title\">Theory &amp; Formulas<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\"><div class=\"vc-section-inner vc-theory\">\n        <h3>Inverse Square Law<\/h3>\n        <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n        <p>For a point source in a free field, SPL drops 6 dB for each doubling of distance.<\/p>\n        <div class=\"vc-example-box\"><div class=\"vc-example-title\">Example \u2014 Machine at 90 dB @ 1 m<\/div>\n            <p>L\u2082 = 90 \u2212 20\u00b7log\u2081\u2080(10\/1) = 90 \u2212 20 = <strong>70 dB at 10 m<\/strong><\/p>\n        <\/div>\n    <\/div><\/div>\n<\/div>\n\n<div class=\"vc-section\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udd17<\/span><span class=\"vc-section-title\">Related Calculators<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-related\"><a class=\"vc-related-link\" href=\"\/calculators\/noise-level-addition\/\">Noise Level Addition<\/a><a class=\"vc-related-link\" href=\"\/calculators\/sound-level-converter\/\">Sound Level Converter<\/a><\/div><\/div><\/div>\n<\/div>\n\n<div class=\"vc-section\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\u2753<\/span><span class=\"vc-section-title\">Frequently Asked Questions<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div><\/div><\/div>\n<\/div>\n\n<div class=\"vc-promo\"><div class=\"vc-promo-text\"><strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>Professional vibration instruments.<\/div><a class=\"vc-promo-link\" href=\"https:\/\/vibromera.eu\/\" target=\"_blank\" rel=\"noopener\">Learn More<\/a><\/div>\n<footer class=\"vc-footer\"><p>\u00a9 2024\u20132025 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a> \u2014 Engineering Calculators<\/p><div class=\"vc-footer-links\"><a href=\"\/calculators\/engineering-calculators\/\">All Calculators<\/a><a href=\"https:\/\/vibromera.eu\/contacts\/\">Contact<\/a><\/div><\/footer>\n<\/div>\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/katex@0.16.11\/dist\/katex.min.js\"><\/script>\n<script>\n(function(){\n    'use strict';\n    function $(id){return document.getElementById(id)}\n    function fmt(n,d){if(isNaN(n))return'\u2014';return n.toFixed(d===undefined?1:d)}\n    function calculate(){\n        var L1=parseFloat($('vc-l1').value),d1=parseFloat($('vc-d1').value),d2=parseFloat($('vc-d2').value);\n        if(isNaN(L1)||!d1||d1<=0||!d2||d2<=0){$('vc-results').classList.remove('vc-visible');return}\n        var atten=20*Math.log10(d2\/d1);var L2=L1-atten;\n        $('vc-r-l2').innerHTML=fmt(L2,1)+' <span class=\"vc-rcard-unit\">dB<\/span>';\n        $('vc-r-atten').innerHTML='\u2212'+fmt(atten,1)+' <span class=\"vc-rcard-unit\">dB<\/span>';\n        $('vc-r-ratio').innerHTML=fmt(d2\/d1,2)+'\u00d7';\n        $('vc-results').classList.add('vc-visible');\n    }\n    document.querySelectorAll('.vc-preset-btn').forEach(function(b){b.addEventListener('click',function(e){e.preventDefault();$('vc-l1').value=this.dataset.l;$('vc-d1').value=this.dataset.d1;$('vc-d2').value=this.dataset.d2;calculate()})});\n    $('vc-form').addEventListener('input',calculate);$('vc-form').addEventListener('change',calculate);\n    $('vc-copy-btn').addEventListener('click',function(){var t='Level at distance: '+$('vc-r-l2').textContent+'\\nAttenuation: '+$('vc-r-atten').textContent;if(navigator.clipboard)navigator.clipboard.writeText(t)});\n    document.querySelectorAll('.vc-section-toggle').forEach(function(b){b.addEventListener('click',function(){var s=this.closest('.vc-section');s.classList.toggle('vc-open');this.setAttribute('aria-expanded',s.classList.contains('vc-open'))})});\n    var faqData=[\n        {q:'How does sound level decrease with distance?',a:'<p>For a point source in free field, SPL decreases by 6 dB for each doubling of distance (inverse square law).<\/p>'},\n        {q:'What is the inverse square law for sound?',a:'<p>L\u2082 = L\u2081 \u2212 20\u00b7log\u2081\u2080(d\u2082\/d\u2081). SPL drops proportionally to the square of the distance ratio.<\/p>'},\n        {q:'Does this formula work indoors?',a:'<p>It applies in the direct field only. Indoors, reflections create a reverberant field where level stays roughly constant beyond a certain distance.<\/p>'},\n        {q:'What about line sources like roads?',a:'<p>Line sources: L\u2082 = L\u2081 \u2212 10\u00b7log\u2081\u2080(d\u2082\/d\u2081), giving only 3 dB per doubling of distance.<\/p>'},\n        {q:'How far to reduce 90 dB to 70 dB?',a:'<p>20 dB reduction needs 10\u00d7 the reference distance. If 90 dB at 1 m, you need 10 m to reach 70 dB.<\/p>'}\n    ];\n    var fl=$('vc-faq-list');faqData.forEach(function(f){fl.innerHTML+='<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>'+f.q+'<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">'+f.a+'<\/div><\/div><\/div>'});\n    fl.addEventListener('click',function(e){var b=e.target.closest('.vc-faq-q');if(b)b.closest('.vc-faq-item').classList.toggle('vc-open')});\n    function renderFormulas(){try{katex.render('L_2 = L_1 - 20 \\\\cdot \\\\log_{10}\\\\!\\\\left(\\\\frac{d_2}{d_1}\\\\right) \\\\quad [\\\\text{dB}]',$('vc-katex-1'),{displayMode:true,throwOnError:false})}catch(e){}}\n    function init(){renderFormulas();calculate()}\n    if(document.readyState==='loading')document.addEventListener('DOMContentLoaded',init);else init();\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Free noise distance attenuation calculator. Calculate sound level at any distance using the inverse square law: L2 = L1 \u2212 20\u00b7log10(d2\/d1).<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100168","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100168","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":2,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100168\/revisions"}],"predecessor-version":[{"id":100934,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100168\/revisions\/100934"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/media?parent=100168"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/categories?post=100168"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/tags?post=100168"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}