<?xml version="1.0" encoding="utf-8"?><mads xmlns="http://www.loc.gov/mads/" xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/mads/
mads.xsd"><authority><topic authority="http://AATesaurus.cultura.gencat.cat/aat/getty_en">impact-echo</topic></authority><related type="broader"><topic>analysis and testing techniques</topic></related> <note xml:lang="en"><![CDATA[ Impact-echo is a nondestructive evaluation technique for masonry construction which detects flaws by monitoring impact-generated sound waves that are disseminated through a structure and are reflected by internal flaws and external surfaces. ]]></note></mads>