'sound-reflecting' originates from a modern English compound of 'sound' and 'reflecting'. 'sound' (the noun meaning 'noise') ultimately comes via Old French 'son' from Latin 'sonus' meaning 'sound' or 'noise'; 'reflecting' derives from Latin 'reflectere' (re- 'back' + flectere 'to bend').

'sound' changed from Latin 'sonus' → Old French 'son' → Middle English 'soun' and became modern English 'sound'. 'reflect' (and forms like 'reflecting') came from Latin 'reflectere' and passed into English via late Latin/Old French forms (e.g. Old French/Medieval Latin reflect-), becoming the modern English 'reflect' and its participle 'reflecting'.

Initially, 'sonus' meant 'sound/noise' and 'reflectere' meant 'to bend back'; over time the components preserved these senses and the compound 'sound-reflecting' came to mean 'having the property of bending sound back (i.e., reflecting sound waves)'.