[{"data":1,"prerenderedAt":690},["ShallowReactive",2],{"site-footer-common":3,"glossary:sound-power-vs-sound-pressure":45,"glossary-related:sound-power-vs-sound-pressure":161},{"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":52,"category":138,"description":139,"extension":140,"meta":141,"navigation":142,"path":143,"relatedTerms":144,"seo":149,"sources":152,"stem":159,"term":47,"__hash__":160},"glossary\u002Fglossary\u002Fsound-power-vs-sound-pressure.md","Sound power vs sound pressure",[49,50,51],"sound power","sound power level","PWL vs SPL",{"type":53,"value":54,"toc":131},"minimark",[55,83,88,96,100,103,107],[56,57,58,62,63,66,67,72,73,77,78,82],"p",{},[59,60,61],"strong",{},"Sound power"," is the total acoustic energy a source emits per unit time, measured in watts. It is an intrinsic property of the source and does not change with listener distance. ",[59,64,65],{},"Sound pressure"," is the local pressure fluctuation at a measurement point, measured in pascals (and reported in ",[68,69,71],"a",{"href":70},"\u002Fglossary\u002Fdecibel","decibels"," as ",[68,74,76],{"href":75},"\u002Fglossary\u002Fsound-pressure-level","SPL","). Pressure falls with distance per the ",[68,79,81],{"href":80},"\u002Fglossary\u002Finverse-square-law","inverse-square law","; power does not.",[84,85,87],"h2",{"id":86},"why-both-matter-for-a-sonic-horn","Why both matter for a sonic horn",[56,89,90,91,95],{},"Vendor datasheets normally publish SPL at 1 m on the bell axis, because that is what specifiers compare. But two horns with identical 150 dB nameplate SPL can radiate different sound power if their directivity differs — a wider radiation pattern delivers more useful energy into the vessel. Sound power level (PWL) is the comparable metric when evaluating total cleaning energy, measured per ",[68,92,94],{"href":93},"\u002Fglossary\u002Fiso-9614-sound-power","ISO 9614",".",[84,97,99],{"id":98},"practical-rule-of-thumb","Practical rule of thumb",[56,101,102],{},"For noise-exposure work at the operator station, use SPL with distance corrections. For cleaning-coverage modelling inside the vessel, sound power and directivity are the more useful inputs.",[84,104,106],{"id":105},"related-terms","Related terms",[108,109,110,116,121,126],"ul",{},[111,112,113],"li",{},[68,114,115],{"href":75},"Sound pressure level",[111,117,118],{},[68,119,120],{"href":70},"Decibel",[111,122,123],{},[68,124,125],{"href":80},"Inverse-square law",[111,127,128],{},[68,129,130],{"href":93},"ISO 9614 (sound power)",{"title":132,"searchDepth":133,"depth":133,"links":134},"",2,[135,136,137],{"id":86,"depth":133,"text":87},{"id":98,"depth":133,"text":99},{"id":105,"depth":133,"text":106},"acoustics-physics","Sound power is the total acoustic energy a source emits per unit time, measured in watts. It is an intrinsic property of the source and does not change with listener distance. Sound pressure is the local pressure fluctuation at a measurement point, measured in pascals (and reported in decibels as SPL). Pressure falls with distance per the inverse-square law; power does not.","md",{},true,"\u002Fglossary\u002Fsound-power-vs-sound-pressure",[145,146,147,148],"sound-pressure-level","decibel","inverse-square-law","iso-9614-sound-power",{"title":150,"description":151},"Sound power vs sound pressure — what's the difference for sonic horns?","Sound power is the total acoustic energy a source emits per second and is a property of the source. Sound pressure is what a microphone measures at a point and falls with distance.",[153,156],{"title":154,"url":155},"Wikipedia — Sound power","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FSound_power",{"title":157,"url":158},"ISO 9614 — Determination of sound power levels","https:\u002F\u002Fwww.iso.org\u002Fstandard\u002F24249.html","glossary\u002Fsound-power-vs-sound-pressure","s-f6ppBgdqiGjcmCwUO7MSFq5tucJMiULv_eua6axuw",[162,348,487,633],{"id":163,"title":164,"aliases":165,"body":167,"category":138,"description":331,"extension":140,"meta":332,"navigation":142,"path":75,"relatedTerms":333,"seo":336,"sources":339,"stem":346,"term":115,"__hash__":347},"glossary\u002Fglossary\u002Fsound-pressure-level.md","Sound pressure level (SPL)",[76,166],"sound pressure level dB",{"type":53,"value":168,"toc":325},[169,187,191,267,271,284,288,304,306],[56,170,171,173,174,176,177,181,182,186],{},[59,172,164],{}," is the logarithmic measure of sound pressure relative to the 20 µPa human-hearing reference, expressed in ",[68,175,71],{"href":70},". It is the primary specification figure for any ",[68,178,180],{"href":179},"\u002Fglossary\u002Fsonic-horn","sonic horn"," or ",[68,183,185],{"href":184},"\u002Fglossary\u002Facoustic-cleaner","acoustic cleaner"," and the metric used to size noise-exposure controls at the work area.",[84,188,190],{"id":189},"industrial-reference-values","Industrial reference values",[192,193,194,207],"table",{},[195,196,197],"thead",{},[198,199,200,204],"tr",{},[201,202,203],"th",{},"SPL (dB)",[201,205,206],{},"Reference",[208,209,210,219,227,235,243,251,259],"tbody",{},[198,211,212,216],{},[213,214,215],"td",{},"0",[213,217,218],{},"Threshold of human hearing",[198,220,221,224],{},[213,222,223],{},"60",[213,225,226],{},"Normal conversation",[198,228,229,232],{},[213,230,231],{},"120",[213,233,234],{},"Threshold of pain",[198,236,237,240],{},[213,238,239],{},"140",[213,241,242],{},"Industrial sonic horn (lower-output models)",[198,244,245,248],{},[213,246,247],{},"160",[213,249,250],{},"Typical cement \u002F ESP sonic horn",[198,252,253,256],{},[213,254,255],{},"180",[213,257,258],{},"Upper limit of pneumatic industrial sonic horns",[198,260,261,264],{},[213,262,263],{},"194",[213,265,266],{},"Theoretical maximum for an undistorted sine wave in air",[84,268,270],{"id":269},"spl-and-cleaning-effectiveness","SPL and cleaning effectiveness",[56,272,273,274,278,279,283],{},"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: ",[68,275,277],{"href":276},"\u002Fglossary\u002Ffrequency","frequency"," determines ",[68,280,282],{"href":281},"\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.",[84,285,287],{"id":286},"spl-and-exposure","SPL and exposure",[56,289,290,291,293,294,298,299,303],{},"Reported nameplate SPL is measured at 1 m on the bell axis. Real exposure at the work area falls with distance per the ",[68,292,81],{"href":80}," and through enclosure attenuation. Compliance with ",[68,295,297],{"href":296},"\u002Fglossary\u002Fosha-29-cfr-1910-95","OSHA 29 CFR 1910.95"," and ",[68,300,302],{"href":301},"\u002Fglossary\u002Feu-directive-2003-10-ec","EU Directive 2003\u002F10\u002FEC"," is calculated from exposure, not from nameplate SPL.",[84,305,106],{"id":105},[108,307,308,312,317,321],{},[111,309,310],{},[68,311,120],{"href":70},[111,313,314],{},[68,315,316],{"href":276},"Frequency",[111,318,319],{},[68,320,47],{"href":143},[111,322,323],{},[68,324,125],{"href":80},{"title":132,"searchDepth":133,"depth":133,"links":326},[327,328,329,330],{"id":189,"depth":133,"text":190},{"id":269,"depth":133,"text":270},{"id":286,"depth":133,"text":287},{"id":105,"depth":133,"text":106},"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.",{},[146,277,334,147,335],"sound-power-vs-sound-pressure","sonic-horn",{"title":337,"description":338},"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.",[340,343],{"title":341,"url":342},"Wikipedia — Sound pressure","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FSound_pressure",{"title":344,"url":345},"Acoustical Society of America — Sound Pressure Level","https:\u002F\u002Fasastandards.org\u002F","glossary\u002Fsound-pressure-level","ayEoQNuJweSv9WGpwDPcx5CMESsbiPd4QPUpIoyQA6M",{"id":349,"title":350,"aliases":351,"body":353,"category":138,"description":474,"extension":140,"meta":475,"navigation":142,"path":70,"relatedTerms":476,"seo":478,"sources":481,"stem":485,"term":120,"__hash__":486},"glossary\u002Fglossary\u002Fdecibel.md","Decibel (dB)",[352,71],"dB",{"type":53,"value":354,"toc":468},[355,362,366,369,373,438,442,450,452],[56,356,357,358,361],{},"The ",[59,359,360],{},"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.",[84,363,365],{"id":364},"why-a-logarithmic-scale","Why a logarithmic scale",[56,367,368],{},"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.",[84,370,372],{"id":371},"reference-points","Reference points",[192,374,375,385],{},[195,376,377],{},[198,378,379,382],{},[201,380,381],{},"Value",[201,383,384],{},"Meaning",[208,386,387,395,403,411,419,430],{},[198,388,389,392],{},[213,390,391],{},"+3 dB",[213,393,394],{},"Sound intensity doubled",[198,396,397,400],{},[213,398,399],{},"+10 dB",[213,401,402],{},"Sound intensity ×10; perceived loudness roughly doubled",[198,404,405,408],{},[213,406,407],{},"+20 dB",[213,409,410],{},"Sound intensity ×100",[198,412,413,416],{},[213,414,415],{},"0 dB SPL",[213,417,418],{},"Reference threshold of hearing (20 µPa)",[198,420,421,424],{},[213,422,423],{},"140 dB SPL",[213,425,426,427,429],{},"Lower end of industrial ",[68,428,180],{"href":179}," output",[198,431,432,435],{},[213,433,434],{},"180 dB SPL",[213,436,437],{},"Upper end of pneumatic industrial cleaning horns",[84,439,441],{"id":440},"weighting","Weighting",[56,443,444,445,298,447,449],{},"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 ",[68,446,297],{"href":296},[68,448,302],{"href":301},". C-weighting (dBC) is used for peak exposure to high-level impulsive sound.",[84,451,106],{"id":105},[108,453,454,458,462],{},[111,455,456],{},[68,457,115],{"href":75},[111,459,460],{},[68,461,316],{"href":276},[111,463,464],{},[68,465,467],{"href":466},"\u002Fglossary\u002Foctave-band","Octave band",{"title":132,"searchDepth":133,"depth":133,"links":469},[470,471,472,473],{"id":364,"depth":133,"text":365},{"id":371,"depth":133,"text":372},{"id":440,"depth":133,"text":441},{"id":105,"depth":133,"text":106},"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.",{},[145,277,147,477],"octave-band",{"title":479,"description":480},"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.",[482],{"title":483,"url":484},"Wikipedia — Decibel","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FDecibel","glossary\u002Fdecibel","RnO0-e6FXXcqpL2fccyibxKPWKiXzYwQXLsx0a4VvbA",{"id":488,"title":125,"aliases":489,"body":492,"category":138,"description":619,"extension":140,"meta":620,"navigation":142,"path":80,"relatedTerms":621,"seo":624,"sources":627,"stem":631,"term":125,"__hash__":632},"glossary\u002Fglossary\u002Finverse-square-law.md",[490,491],"1\u002Fr² law (acoustic)","geometric spreading",{"type":53,"value":493,"toc":613},[494,505,509,512,566,570,583,587,595,597],[56,495,357,496,498,499,501,502,504],{},[59,497,81],{}," states that the intensity of a point-source sound wave falls as 1\u002Fr² with distance. Expressed in ",[68,500,71],{"href":70},", ",[68,503,76],{"href":75}," decreases by approximately 6 dB for every doubling of distance from the source in a free field.",[84,506,508],{"id":507},"worked-example-for-a-sonic-horn","Worked example for a sonic horn",[56,510,511],{},"A horn rated at 150 dB SPL at 1 m on the bell axis will produce, in free-field conditions:",[192,513,514,524],{},[195,515,516],{},[198,517,518,521],{},[201,519,520],{},"Distance",[201,522,523],{},"Approximate SPL",[208,525,526,534,542,550,558],{},[198,527,528,531],{},[213,529,530],{},"1 m",[213,532,533],{},"150 dB",[198,535,536,539],{},[213,537,538],{},"2 m",[213,540,541],{},"144 dB",[198,543,544,547],{},[213,545,546],{},"4 m",[213,548,549],{},"138 dB",[198,551,552,555],{},[213,553,554],{},"8 m",[213,556,557],{},"132 dB",[198,559,560,563],{},[213,561,562],{},"16 m",[213,564,565],{},"126 dB",[84,567,569],{"id":568},"where-the-rule-breaks-down","Where the rule breaks down",[56,571,572,573,577,578,582],{},"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 ",[68,574,576],{"href":575},"\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, ",[68,579,581],{"href":580},"\u002Fglossary\u002Fattenuation-acoustic","attenuation"," absorbs additional energy beyond geometric spreading.",[84,584,586],{"id":585},"why-it-matters-for-noise-exposure","Why it matters for noise exposure",[56,588,589,590,181,592,594],{},"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 ",[68,591,297],{"href":296},[68,593,302],{"href":301}," action levels.",[84,596,106],{"id":105},[108,598,599,603,608],{},[111,600,601],{},[68,602,115],{"href":75},[111,604,605],{},[68,606,607],{"href":580},"Attenuation (acoustic)",[111,609,610],{},[68,611,612],{"href":575},"Near field \u002F far field",{"title":132,"searchDepth":133,"depth":133,"links":614},[615,616,617,618],{"id":507,"depth":133,"text":508},{"id":568,"depth":133,"text":569},{"id":585,"depth":133,"text":586},{"id":105,"depth":133,"text":106},"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.",{},[145,622,623],"attenuation-acoustic","near-field-far-field",{"title":625,"description":626},"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.",[628],{"title":629,"url":630},"Wikipedia — Inverse-square law","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FInverse-square_law","glossary\u002Finverse-square-law","EYJdDFIbE5CXCp0ONbKYLs6jeZE8zRgWkX6myn6g82k",{"id":634,"title":130,"aliases":635,"body":637,"category":678,"description":679,"extension":140,"meta":680,"navigation":142,"path":93,"relatedTerms":681,"seo":682,"sources":685,"stem":688,"term":94,"__hash__":689},"glossary\u002Fglossary\u002Fiso-9614-sound-power.md",[94,636],"sound power determination standard",{"type":53,"value":638,"toc":674},[639,645,649,655,658,660],[56,640,357,641,644],{},[59,642,643],{},"ISO 9614 series"," specifies methods for determining sound-power levels (PWL) from sound-intensity measurements. It is the international reference for measuring total acoustic output from a source — distinct from sound-pressure measurement at a single point, which depends on distance and direction.",[84,646,648],{"id":647},"why-it-matters-for-sonic-horn-specification","Why it matters for sonic-horn specification",[56,650,651,652,654],{},"Vendor ",[68,653,76],{"href":75}," figures published at 1 m on the bell axis are useful but incomplete — two horns with identical 150 dB SPL at 1 m can deliver different total sound power if their directivity differs. ISO 9614 sound-power measurement is the rigorous way to compare total acoustic output between competing horn designs, and a more meaningful figure for predicting cleaning coverage inside a vessel.",[56,656,657],{},"In practice, sound-power data is rarely published on commercial horn datasheets but can be requested for specification or third-party-verified comparisons.",[84,659,106],{"id":105},[108,661,662,666,670],{},[111,663,664],{},[68,665,47],{"href":143},[111,667,668],{},[68,669,115],{"href":75},[111,671,672],{},[68,673,120],{"href":70},{"title":132,"searchDepth":133,"depth":133,"links":675},[676,677],{"id":647,"depth":133,"text":648},{"id":105,"depth":133,"text":106},"standards-regulations","The ISO 9614 series specifies methods for determining sound-power levels (PWL) from sound-intensity measurements. It is the international reference for measuring total acoustic output from a source — distinct from sound-pressure measurement at a single point, which depends on distance and direction.",{},[334,145,146],{"title":683,"description":684},"ISO 9614 — international standard for determining sound-power levels","ISO 9614 series specifies methods for determining sound-power levels from sound-intensity measurements. The reference method for comparing total acoustic output of sonic horns.",[686],{"title":687,"url":158},"ISO — ISO 9614 series","glossary\u002Fiso-9614-sound-power","abG0Se7BgkuEln4DkjEbl3C6d8Wyv5Q3JwbErAfw0x4",1782613716035]