Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical engineer. The application of acoustics is present in almost all aspects of modern society with the most obvious being the audio and noise control industries.

ध्वनिकी (Acoustics) भौतिकी की वह शाखा है जिसके अन्तर्गत ध्वनि तरंगो, अपश्रव्य तरंगों एवं पराश्रव्य तरंगों सहित ठोस, द्रव एवं गैसों में संचारित होने वाली सभी प्रकार की यांत्रिक तरंगों का अध्ययन किया जाता है।