{"id":801,"date":"2025-05-26T11:05:57","date_gmt":"2025-05-26T02:05:57","guid":{"rendered":"https:\/\/acoustic-measurement.com\/?post_type=technology&#038;p=801"},"modified":"2025-05-26T11:05:58","modified_gmt":"2025-05-26T02:05:58","slug":"soundintensitymethodsoundpower","status":"publish","type":"technology","link":"https:\/\/acoustic-measurement.com\/en\/technology\/soundintensitymethodsoundpower\/","title":{"rendered":"Acoustic Power Measurement by the Sound Intensity Method"},"content":{"rendered":"\n<p>When measuring acoustic power using the sound intensity method, it becomes possible to perform measurements even near machinery or in environments with steady background noise.<br>This method is very straightforward: the acoustic power is obtained by multiplying the average normal sound intensity over the measurement surface by the surface area.<br>The first step is to define this virtual measurement surface.<\/p>\n\n\n\n<p>As long as there are no other sound sources or absorbing materials inside the defined measurement surface, its shape can be arbitrary.<br>The floor is assumed to reflect all sound perfectly and is therefore not included in the measurement surface.<br>Theoretically, the distance of the measurement surface from the sound source does not affect the results.<\/p>\n\n\n\n<p>Two examples are shown below.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"850\" height=\"939\" src=\"https:\/\/acoustic-measurement.com\/wp-content\/uploads\/310-2.jpg\" alt=\"\" class=\"wp-image-571\" srcset=\"https:\/\/acoustic-measurement.com\/wp-content\/uploads\/310-2.jpg 850w, https:\/\/acoustic-measurement.com\/wp-content\/uploads\/310-2-272x300.jpg 272w, https:\/\/acoustic-measurement.com\/wp-content\/uploads\/310-2-768x848.jpg 768w\" sizes=\"auto, (max-width: 850px) 100vw, 850px\" \/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Rectangular Box<\/h3>\n\n\n\n<p>The shape and size of the measurement surface can be arbitrary.<br>A rectangular box is easy to define and, because of its flat surfaces, makes it simple to average the intensity over each plane.<br>The partial acoustic power from each surface is calculated individually and then summed.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Hemisphere<\/h3>\n\n\n\n<p>Using a hemispherical measurement surface minimizes the number of required measurement points.<br>In a free-field environment with an omnidirectional source, the intensity is uniform at all points on the hemisphere.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Spatial Averaging<\/h2>\n\n\n\n<p>Once the measurement surface is defined, the normal component of the intensity relative to the surface must be measured and spatially averaged.<br>The measurement surface can be defined physically using a grid, or simply by specifying distances from a reference point.<\/p>\n\n\n\n<p>ISO 9614 consists of three parts, each defining a different measurement method:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Part 1: Averaging at discrete points<\/li>\n\n\n\n<li>Part 2 and Part 3: Averaging through scanning across the measurement surface<\/li>\n\n\n\n<li>Part 3: Additional requirements apply for certain measurement environments<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Averaging at Discrete Measurement Points (Discrete-Point Method)<\/h2>\n\n\n\n<p>In this method, the measurement surface is divided into small segments, and individual measurements are taken at each segment.<br>The measurement points are usually arranged in a grid pattern.<br>You can use rulers or tape measures, but creating a guide using string or wire is also effective.<br>By averaging the results and multiplying by the area, the total acoustic power for the entire measurement surface is obtained.<\/p>\n\n\n\n<p>Neither method is perfect for every situation; in some cases, both methods can be valid.<br>The scanning method offers a closer approximation to continuous spatial integration and may provide more accurate results, but it requires moving the probe at a constant speed and covering the measurement surface evenly.<\/p>\n\n\n\n<p>On the other hand, the discrete-point method offers excellent reproducibility.<br>When repeated measurements are required, both methods can be easily automated, improving precision.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Scanning the Measurement Surface (Scanning Method)<\/h2>\n\n\n\n<p>Using an appropriate averaging time, the probe is moved across the measurement surface much like painting the surface.<br>This produces a single value for the spatially averaged intensity.<br>Multiplying this value by the surface area gives the acoustic power from that surface.<br>The acoustic powers from all measurement surfaces are then summed.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"850\" height=\"531\" src=\"https:\/\/acoustic-measurement.com\/wp-content\/uploads\/310-3.jpg\" alt=\"\" class=\"wp-image-572\" srcset=\"https:\/\/acoustic-measurement.com\/wp-content\/uploads\/310-3.jpg 850w, https:\/\/acoustic-measurement.com\/wp-content\/uploads\/310-3-300x187.jpg 300w, https:\/\/acoustic-measurement.com\/wp-content\/uploads\/310-3-768x480.jpg 768w\" sizes=\"auto, (max-width: 850px) 100vw, 850px\" \/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>When measuring acoustic power using the sound intensity method, it becomes possible to perform measurements even near machinery or in environments with steady background noise.This method is very straightforward: the acoustic power is obtained by multiplying the average normal sound intensity over the measurement surface by the surface area.The first step is to define this [&hellip;]<\/p>\n","protected":false},"featured_media":0,"parent":0,"template":"","solution_cat":[2],"class_list":["post-801","technology","type-technology","status-publish","hentry","solution_cat-tax_power","en-US"],"acf":[],"_links":{"self":[{"href":"https:\/\/acoustic-measurement.com\/wp-json\/wp\/v2\/technology\/801","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/acoustic-measurement.com\/wp-json\/wp\/v2\/technology"}],"about":[{"href":"https:\/\/acoustic-measurement.com\/wp-json\/wp\/v2\/types\/technology"}],"wp:attachment":[{"href":"https:\/\/acoustic-measurement.com\/wp-json\/wp\/v2\/media?parent=801"}],"wp:term":[{"taxonomy":"solution_cat","embeddable":true,"href":"https:\/\/acoustic-measurement.com\/wp-json\/wp\/v2\/solution_cat?post=801"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}