<?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">acoustics concepts</topic></authority><related type="narrower"><topic>sound absorption</topic></related><related type="narrower"><topic>sound</topic></related><related type="narrower"><topic>echo</topic></related><related type="narrower"><topic>acoustic transmission</topic></related><related type="narrower"><topic>pitch</topic></related><related type="narrower"><topic>resonance</topic></related><related type="narrower"><topic>acoustic emission</topic></related><related type="narrower"><topic>timbre</topic></related><related type="narrower"><topic>silence</topic></related><related type="other"><topic>acoustical properties</topic></related><related type="other"><topic>acoustics</topic></related><related type="broader"><topic>physics concepts</topic></related><variant type="other"><topic>acoustics concept</topic></variant><variant type="other"><topic>concepts, acoustics</topic></variant> <note xml:lang="en"><![CDATA[ Physics concepts dealing with the properties of sound.  ]]></note></mads>