[{"data":1,"prerenderedAt":810},["ShallowReactive",2],{"site-footer-common":3,"glossary:decibel":45,"glossary-related:decibel":221},{"id":4,"extension":5,"footer":6,"meta":40,"navbar":41,"stem":43,"__hash__":44},"common\u002Fcommon.yml","yml",{"tagline":7,"links":8,"sections":9},"Acoustic cleaning intelligence for industrial fouling, soot, ash, dust and build-up.",[],[10,19,31],{"title":11,"links":12},"Product",[13,16],{"label":14,"to":15},"How it works","\u002F#product",{"label":17,"to":18},"Cost assessment","\u002F#hero",{"title":20,"links":21},"Company",[22,25,28],{"label":23,"to":24},"What we build","\u002F#about",{"label":26,"to":27},"Careers","\u002F#careers",{"label":29,"to":30},"Contact","\u002F#contact",{"title":32,"links":33},"Resources",[34,37],{"label":35,"to":36},"Blog","\u002Fresources\u002Fblog",{"label":38,"to":39},"Glossary","\u002Fglossary",{},{"links":42},[],"common","YocmZRy1AYfBbpgGVms-zhdiABlF8VTxHx6h4rDmZBA",{"id":46,"title":47,"aliases":48,"body":51,"category":200,"description":201,"extension":202,"meta":203,"navigation":204,"path":205,"relatedTerms":206,"seo":211,"sources":214,"stem":218,"term":219,"__hash__":220},"glossary\u002Fglossary\u002Fdecibel.md","Decibel (dB)",[49,50],"dB","decibels",{"type":52,"value":53,"toc":192},"minimark",[54,63,68,71,75,149,153,166,170],[55,56,57,58,62],"p",{},"The ",[59,60,61],"strong",{},"decibel (dB)"," is a logarithmic unit used to express the ratio between two values of an acoustic quantity — most commonly sound pressure, sound intensity or sound power. A 10 dB increase represents a tenfold increase in intensity and a perceived roughly doubled loudness. A 3 dB increase represents a doubling of intensity.",[64,65,67],"h2",{"id":66},"why-a-logarithmic-scale","Why a logarithmic scale",[55,69,70],{},"Human hearing — and the practical range of industrial acoustic cleaning — spans more than ten orders of magnitude of sound pressure (20 µPa to several hundred Pa). A linear scale would be unwieldy. The logarithmic decibel compresses this into a tractable 0–180 dB band and aligns with how the ear actually responds to intensity changes.",[64,72,74],{"id":73},"reference-points","Reference points",[76,77,78,91],"table",{},[79,80,81],"thead",{},[82,83,84,88],"tr",{},[85,86,87],"th",{},"Value",[85,89,90],{},"Meaning",[92,93,94,103,111,119,127,141],"tbody",{},[82,95,96,100],{},[97,98,99],"td",{},"+3 dB",[97,101,102],{},"Sound intensity doubled",[82,104,105,108],{},[97,106,107],{},"+10 dB",[97,109,110],{},"Sound intensity ×10; perceived loudness roughly doubled",[82,112,113,116],{},[97,114,115],{},"+20 dB",[97,117,118],{},"Sound intensity ×100",[82,120,121,124],{},[97,122,123],{},"0 dB SPL",[97,125,126],{},"Reference threshold of hearing (20 µPa)",[82,128,129,132],{},[97,130,131],{},"140 dB SPL",[97,133,134,135,140],{},"Lower end of industrial ",[136,137,139],"a",{"href":138},"\u002Fglossary\u002Fsonic-horn","sonic horn"," output",[82,142,143,146],{},[97,144,145],{},"180 dB SPL",[97,147,148],{},"Upper end of pneumatic industrial cleaning horns",[64,150,152],{"id":151},"weighting","Weighting",[55,154,155,156,160,161,165],{},"For noise-exposure work, raw dB is often weighted to better reflect human hearing. A-weighting (dBA) is the standard for occupational-noise calculations under ",[136,157,159],{"href":158},"\u002Fglossary\u002Fosha-29-cfr-1910-95","OSHA 29 CFR 1910.95"," and ",[136,162,164],{"href":163},"\u002Fglossary\u002Feu-directive-2003-10-ec","EU Directive 2003\u002F10\u002FEC",". C-weighting (dBC) is used for peak exposure to high-level impulsive sound.",[64,167,169],{"id":168},"related-terms","Related terms",[171,172,173,180,186],"ul",{},[174,175,176],"li",{},[136,177,179],{"href":178},"\u002Fglossary\u002Fsound-pressure-level","Sound pressure level",[174,181,182],{},[136,183,185],{"href":184},"\u002Fglossary\u002Ffrequency","Frequency",[174,187,188],{},[136,189,191],{"href":190},"\u002Fglossary\u002Foctave-band","Octave band",{"title":193,"searchDepth":194,"depth":194,"links":195},"",2,[196,197,198,199],{"id":66,"depth":194,"text":67},{"id":73,"depth":194,"text":74},{"id":151,"depth":194,"text":152},{"id":168,"depth":194,"text":169},"acoustics-physics","The decibel (dB) is a logarithmic unit used to express the ratio between two values of an acoustic quantity — most commonly sound pressure, sound intensity or sound power. A 10 dB increase represents a tenfold increase in intensity and a perceived roughly doubled loudness. A 3 dB increase represents a doubling of intensity.","md",{},true,"\u002Fglossary\u002Fdecibel",[207,208,209,210],"sound-pressure-level","frequency","inverse-square-law","octave-band",{"title":212,"description":213},"Decibel (dB) — logarithmic sound unit explained for industrial use","The decibel is a logarithmic ratio used to express sound pressure, sound intensity and sound power. A 10 dB rise represents a tenfold rise in intensity.",[215],{"title":216,"url":217},"Wikipedia — Decibel","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FDecibel","glossary\u002Fdecibel","Decibel","RnO0-e6FXXcqpL2fccyibxKPWKiXzYwQXLsx0a4VvbA",[222,399,585,730],{"id":223,"title":224,"aliases":225,"body":228,"category":200,"description":381,"extension":202,"meta":382,"navigation":204,"path":178,"relatedTerms":383,"seo":387,"sources":390,"stem":397,"term":179,"__hash__":398},"glossary\u002Fglossary\u002Fsound-pressure-level.md","Sound pressure level (SPL)",[226,227],"SPL","sound pressure level dB",{"type":52,"value":229,"toc":375},[230,246,250,320,324,335,339,352,354],[55,231,232,234,235,237,238,240,241,245],{},[59,233,224],{}," is the logarithmic measure of sound pressure relative to the 20 µPa human-hearing reference, expressed in ",[136,236,50],{"href":205},". It is the primary specification figure for any ",[136,239,139],{"href":138}," or ",[136,242,244],{"href":243},"\u002Fglossary\u002Facoustic-cleaner","acoustic cleaner"," and the metric used to size noise-exposure controls at the work area.",[64,247,249],{"id":248},"industrial-reference-values","Industrial reference values",[76,251,252,262],{},[79,253,254],{},[82,255,256,259],{},[85,257,258],{},"SPL (dB)",[85,260,261],{},"Reference",[92,263,264,272,280,288,296,304,312],{},[82,265,266,269],{},[97,267,268],{},"0",[97,270,271],{},"Threshold of human hearing",[82,273,274,277],{},[97,275,276],{},"60",[97,278,279],{},"Normal conversation",[82,281,282,285],{},[97,283,284],{},"120",[97,286,287],{},"Threshold of pain",[82,289,290,293],{},[97,291,292],{},"140",[97,294,295],{},"Industrial sonic horn (lower-output models)",[82,297,298,301],{},[97,299,300],{},"160",[97,302,303],{},"Typical cement \u002F ESP sonic horn",[82,305,306,309],{},[97,307,308],{},"180",[97,310,311],{},"Upper limit of pneumatic industrial sonic horns",[82,313,314,317],{},[97,315,316],{},"194",[97,318,319],{},"Theoretical maximum for an undistorted sine wave in air",[64,321,323],{"id":322},"spl-and-cleaning-effectiveness","SPL and cleaning effectiveness",[55,325,326,327,329,330,334],{},"Cleaning energy scales with intensity, which doubles for every 3 dB rise. A 150 dB horn delivers roughly twice the energy of a 147 dB horn at the same distance. SPL is not, however, the only selection criterion: ",[136,328,208],{"href":184}," determines ",[136,331,333],{"href":332},"\u002Fglossary\u002Fwavelength","wavelength"," and therefore penetration. A 150 dB low-frequency horn typically out-cleans a 160 dB high-frequency horn in a large open vessel.",[64,336,338],{"id":337},"spl-and-exposure","SPL and exposure",[55,340,341,342,346,347,160,349,351],{},"Reported nameplate SPL is measured at 1 m on the bell axis. Real exposure at the work area falls with distance per the ",[136,343,345],{"href":344},"\u002Fglossary\u002Finverse-square-law","inverse-square law"," and through enclosure attenuation. Compliance with ",[136,348,159],{"href":158},[136,350,164],{"href":163}," is calculated from exposure, not from nameplate SPL.",[64,353,169],{"id":168},[171,355,356,360,364,370],{},[174,357,358],{},[136,359,219],{"href":205},[174,361,362],{},[136,363,185],{"href":184},[174,365,366],{},[136,367,369],{"href":368},"\u002Fglossary\u002Fsound-power-vs-sound-pressure","Sound power vs sound pressure",[174,371,372],{},[136,373,374],{"href":344},"Inverse-square law",{"title":193,"searchDepth":194,"depth":194,"links":376},[377,378,379,380],{"id":248,"depth":194,"text":249},{"id":322,"depth":194,"text":323},{"id":337,"depth":194,"text":338},{"id":168,"depth":194,"text":169},"Sound pressure level (SPL) is the logarithmic measure of sound pressure relative to the 20 µPa human-hearing reference, expressed in decibels. It is the primary specification figure for any sonic horn or acoustic cleaner and the metric used to size noise-exposure controls at the work area.",{},[384,208,385,209,386],"decibel","sound-power-vs-sound-pressure","sonic-horn",{"title":388,"description":389},"Sound pressure level (SPL) — definition, industrial-cleaning ranges","SPL is the logarithmic measure of sound pressure in decibels relative to a 20 µPa reference. Industrial sonic horns operate at 140–180 dB SPL.",[391,394],{"title":392,"url":393},"Wikipedia — Sound pressure","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FSound_pressure",{"title":395,"url":396},"Acoustical Society of America — Sound Pressure Level","https:\u002F\u002Fasastandards.org\u002F","glossary\u002Fsound-pressure-level","ayEoQNuJweSv9WGpwDPcx5CMESsbiPd4QPUpIoyQA6M",{"id":400,"title":401,"aliases":402,"body":406,"category":200,"description":569,"extension":202,"meta":570,"navigation":204,"path":184,"relatedTerms":571,"seo":576,"sources":579,"stem":583,"term":185,"__hash__":584},"glossary\u002Fglossary\u002Ffrequency.md","Frequency (Hz)",[403,404,405],"Hz","acoustic frequency","sonic horn frequency",{"type":52,"value":407,"toc":564},[408,419,423,512,516,527,529],[55,409,410,412,413,415,416,418],{},[59,411,185],{}," is the number of acoustic cycles per second, measured in hertz (Hz). For industrial acoustic cleaning it is the single most important selection parameter after ",[136,414,226],{"href":178},": frequency determines ",[136,417,333],{"href":332},", which in turn governs how the sound wave penetrates the vessel.",[64,420,422],{"id":421},"industrial-cleaning-bands","Industrial cleaning bands",[76,424,425,441],{},[79,426,427],{},[82,428,429,432,435,438],{},[85,430,431],{},"Band",[85,433,434],{},"Range",[85,436,437],{},"Wavelength in air",[85,439,440],{},"Typical use",[92,442,443,466,491],{},[82,444,445,448,451,454],{},[97,446,447],{},"Infrasonic",[97,449,450],{},"12–30 Hz",[97,452,453],{},"11–28 m",[97,455,456,460,461,465],{},[136,457,459],{"href":458},"\u002Fglossary\u002Frecovery-boiler","Recovery boilers",", ",[136,462,464],{"href":463},"\u002Fglossary\u002Fwaste-to-energy","WtE"," flue paths",[82,467,468,471,474,477],{},[97,469,470],{},"Low frequency",[97,472,473],{},"60–250 Hz",[97,475,476],{},"1.4–5.7 m",[97,478,479,460,483,460,487],{},[136,480,482],{"href":481},"\u002Fglossary\u002Felectrostatic-precipitator","ESPs",[136,484,486],{"href":485},"\u002Fglossary\u002Fpreheater-cyclone","preheater cyclones",[136,488,490],{"href":489},"\u002Fglossary\u002Fsilo","silos",[82,492,493,496,499,502],{},[97,494,495],{},"High frequency",[97,497,498],{},"250–450 Hz",[97,500,501],{},"0.75–1.4 m",[97,503,504,460,508],{},[136,505,507],{"href":506},"\u002Fglossary\u002Ffabric-filter","Fabric filters",[136,509,511],{"href":510},"\u002Fglossary\u002Fselective-catalytic-reduction","SCR catalysts",[64,513,515],{"id":514},"trade-off","Trade-off",[55,517,518,519,160,523,526],{},"Long wavelengths diffract around obstructions and penetrate further; short wavelengths concentrate more energy in a smaller volume. The frequency choice is therefore a trade between ",[520,521,522],"em",{},"reach",[520,524,525],{},"energy density",". Many real installations combine both bands: low-frequency horns clean the bulk volume; high-frequency horns clean dense bag rows or catalyst faces.",[64,528,169],{"id":168},[171,530,531,536,540,546,552,558],{},[174,532,533],{},[136,534,535],{"href":332},"Wavelength",[174,537,538],{},[136,539,179],{"href":178},[174,541,542],{},[136,543,545],{"href":544},"\u002Fglossary\u002Ffundamental-frequency","Fundamental frequency",[174,547,548],{},[136,549,551],{"href":550},"\u002Fglossary\u002Flow-frequency-acoustic-cleaner","Low-frequency acoustic cleaner",[174,553,554],{},[136,555,557],{"href":556},"\u002Fglossary\u002Fhigh-frequency-acoustic-cleaner","High-frequency acoustic cleaner",[174,559,560],{},[136,561,563],{"href":562},"\u002Fglossary\u002Finfrasonic-cleaner","Infrasonic cleaner",{"title":193,"searchDepth":194,"depth":194,"links":565},[566,567,568],{"id":421,"depth":194,"text":422},{"id":514,"depth":194,"text":515},{"id":168,"depth":194,"text":169},"Frequency is the number of acoustic cycles per second, measured in hertz (Hz). For industrial acoustic cleaning it is the single most important selection parameter after SPL: frequency determines wavelength, which in turn governs how the sound wave penetrates the vessel.",{},[333,207,572,573,574,575],"fundamental-frequency","low-frequency-acoustic-cleaner","high-frequency-acoustic-cleaner","infrasonic-cleaner",{"title":577,"description":578},"Frequency (Hz) — selection bands for industrial sonic horns","Frequency is the number of acoustic cycles per second, measured in hertz. Industrial acoustic cleaners operate at 12–30 Hz (infrasonic), 60–250 Hz (low) or 250–450 Hz (high).",[580],{"title":581,"url":582},"Wikipedia — Frequency","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FFrequency","glossary\u002Ffrequency","7P2gkJzmA_x2ddonur2FhvOEPYFBCmPrnuK_ZNv8mqc",{"id":586,"title":374,"aliases":587,"body":590,"category":200,"description":716,"extension":202,"meta":717,"navigation":204,"path":344,"relatedTerms":718,"seo":721,"sources":724,"stem":728,"term":374,"__hash__":729},"glossary\u002Fglossary\u002Finverse-square-law.md",[588,589],"1\u002Fr² law (acoustic)","geometric spreading",{"type":52,"value":591,"toc":710},[592,602,606,609,663,667,680,684,692,694],[55,593,57,594,596,597,460,599,601],{},[59,595,345],{}," states that the intensity of a point-source sound wave falls as 1\u002Fr² with distance. Expressed in ",[136,598,50],{"href":205},[136,600,226],{"href":178}," decreases by approximately 6 dB for every doubling of distance from the source in a free field.",[64,603,605],{"id":604},"worked-example-for-a-sonic-horn","Worked example for a sonic horn",[55,607,608],{},"A horn rated at 150 dB SPL at 1 m on the bell axis will produce, in free-field conditions:",[76,610,611,621],{},[79,612,613],{},[82,614,615,618],{},[85,616,617],{},"Distance",[85,619,620],{},"Approximate SPL",[92,622,623,631,639,647,655],{},[82,624,625,628],{},[97,626,627],{},"1 m",[97,629,630],{},"150 dB",[82,632,633,636],{},[97,634,635],{},"2 m",[97,637,638],{},"144 dB",[82,640,641,644],{},[97,642,643],{},"4 m",[97,645,646],{},"138 dB",[82,648,649,652],{},[97,650,651],{},"8 m",[97,653,654],{},"132 dB",[82,656,657,660],{},[97,658,659],{},"16 m",[97,661,662],{},"126 dB",[64,664,666],{"id":665},"where-the-rule-breaks-down","Where the rule breaks down",[55,668,669,670,674,675,679],{},"Three real conditions modify the textbook result. Inside a vessel, reflections from walls and tube banks reinforce the sound field and slow the fall-off; geometry no longer behaves as a free field. In the ",[136,671,673],{"href":672},"\u002Fglossary\u002Fnear-field-far-field","near field"," of the bell, the simple 1\u002Fr² rule does not apply. And at long distances and high frequencies, ",[136,676,678],{"href":677},"\u002Fglossary\u002Fattenuation-acoustic","attenuation"," absorbs additional energy beyond geometric spreading.",[64,681,683],{"id":682},"why-it-matters-for-noise-exposure","Why it matters for noise exposure",[55,685,686,687,240,689,691],{},"Worker exposure assessments work backwards from the inverse-square law: knowing the nameplate SPL and the operator-station distance, the predicted exposure can be compared with ",[136,688,159],{"href":158},[136,690,164],{"href":163}," action levels.",[64,693,169],{"id":168},[171,695,696,700,705],{},[174,697,698],{},[136,699,179],{"href":178},[174,701,702],{},[136,703,704],{"href":677},"Attenuation (acoustic)",[174,706,707],{},[136,708,709],{"href":672},"Near field \u002F far field",{"title":193,"searchDepth":194,"depth":194,"links":711},[712,713,714,715],{"id":604,"depth":194,"text":605},{"id":665,"depth":194,"text":666},{"id":682,"depth":194,"text":683},{"id":168,"depth":194,"text":169},"The inverse-square law states that the intensity of a point-source sound wave falls as 1\u002Fr² with distance. Expressed in decibels, SPL decreases by approximately 6 dB for every doubling of distance from the source in a free field.",{},[207,719,720],"attenuation-acoustic","near-field-far-field",{"title":722,"description":723},"Inverse-square law — sound pressure halves every doubling of distance","In free-field conditions sound intensity falls as 1\u002Fr². Sound pressure level drops by approximately 6 dB for each doubling of distance from the source.",[725],{"title":726,"url":727},"Wikipedia — Inverse-square law","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FInverse-square_law","glossary\u002Finverse-square-law","EYJdDFIbE5CXCp0ONbKYLs6jeZE8zRgWkX6myn6g82k",{"id":731,"title":191,"aliases":732,"body":735,"category":200,"description":796,"extension":202,"meta":797,"navigation":204,"path":190,"relatedTerms":798,"seo":801,"sources":804,"stem":808,"term":191,"__hash__":809},"glossary\u002Fglossary\u002Foctave-band.md",[733,734],"octave bands","1\u002F3 octave band",{"type":52,"value":736,"toc":792},[737,753,757,768,770],[55,738,739,740,743,744,747,748,160,750,752],{},"An ",[59,741,742],{},"octave band"," is a frequency range whose upper bound is twice the lower bound. Standard centre frequencies (in Hz) used for industrial-noise work are 31.5, 63, 125, 250, 500, 1000, 2000, 4000, 8000 and 16000. ",[59,745,746],{},"One-third octave bands"," subdivide each octave into three for higher resolution. Reporting SPL as a spectrum across these bands — instead of as a single broadband number — is the standard format for noise-exposure analysis under ",[136,749,159],{"href":158},[136,751,164],{"href":163},".",[64,754,756],{"id":755},"why-octave-band-data-matters-for-sonic-horns","Why octave-band data matters for sonic horns",[55,758,759,760,762,763,767],{},"A 75 Hz ",[136,761,139],{"href":138}," puts most of its energy into the 63 Hz octave band, with smaller amounts in adjacent bands from harmonic content. Exposure assessments at the operator station — and the design of any ",[136,764,766],{"href":765},"\u002Fglossary\u002Fsound-attenuation-enclosure-sonic-horn","sound-attenuation enclosure"," — depend on knowing the spectrum, not just the broadband SPL. Hearing-protection rating (NRR \u002F SNR) is also octave-band-dependent.",[64,769,169],{"id":168},[171,771,772,776,780,784,788],{},[174,773,774],{},[136,775,185],{"href":184},[174,777,778],{},[136,779,219],{"href":205},[174,781,782],{},[136,783,179],{"href":178},[174,785,786],{},[136,787,159],{"href":158},[174,789,790],{},[136,791,164],{"href":163},{"title":193,"searchDepth":194,"depth":194,"links":793},[794,795],{"id":755,"depth":194,"text":756},{"id":168,"depth":194,"text":169},"An octave band is a frequency range whose upper bound is twice the lower bound. Standard centre frequencies (in Hz) used for industrial-noise work are 31.5, 63, 125, 250, 500, 1000, 2000, 4000, 8000 and 16000. One-third octave bands subdivide each octave into three for higher resolution. Reporting SPL as a spectrum across these bands — instead of as a single broadband number — is the standard format for noise-exposure analysis under OSHA 29 CFR 1910.95 and EU Directive 2003\u002F10\u002FEC.",{},[208,384,207,799,800],"osha-29-cfr-1910-95","eu-directive-2003-10-ec",{"title":802,"description":803},"Octave band — how sonic horn noise is reported for exposure analysis","An octave band is a frequency range where the upper bound is twice the lower. Octave-band SPL data is the standard format for noise-exposure analysis under OSHA and EU 2003\u002F10\u002FEC.",[805],{"title":806,"url":807},"Wikipedia — Octave band","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FOctave_band","glossary\u002Foctave-band","mvFr8nIR-90rIMQrkwCbAf6VceeDy_9Nn-ZTKmcDyD4",1782613716034]