<?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">tone difference apparatuses</topic></authority><related type="broader"><topic>sound devices</topic></related><variant type="other"><topic>tone difference apparatus</topic></variant> <note xml:lang="en"><![CDATA[ Instruments for measuring the frequencies of tones or exact pitch, as a set of graduated tuning forks. An advancement of Reed's tonometer, providing more tones. ]]></note></mads>