<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31327474</termId><termName>echo</termName><termType>PT</termType><termNote><![CDATA[ A packet of sound waves that has been reflected or otherwise returned with a sufficient delay and magnitude to be perceived as a signal distinct from the original transmission. ]]></termNote><termCreatedDate>2026-03-30 20:28:15</termCreatedDate><relation><relationType>UF</relationType><termId>31327477</termId><termName>sound reverberation</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31327475</termId><termName>echoes</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31327476</termId><termName>reverberation, sound</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31308500</termId><termName>acoustics concepts</termName><termType>PT</termType></relation></term>  </Zthes>