acoustic
adjectiverelated to sound or to the sense of hearing 声音的；音响的；听觉的 - [usually before noun]
(of a musical instrument or performance 乐器或演奏 designed to make natural sound, not sound amplified (= made louder) by electrical equipment 原声的；自然声的 
Word Originmid 17th cent.: from Greek akoustikos, from akouein ‘hear’.