An audio engineer (also known as a sound engineer or recording engineer) helps to produce a recording or a live performance, balancing and adjusting sound sources using equalization, dynamics processing and audio effects, mixing, reproduction, and reinforcement of sound. Audio engineers work on the "technical aspect of recording—the placing of microphones, pre-amp knobs, the setting of levels. The physical recording of any project is done by an engineer…"

Sound engineering is increasingly viewed as a creative profession and art form, where musical instruments and technology are used to produce sound for film, radio, television, music and video games. Audio engineers also set up, sound check, and do live sound mixing using a mixing console and a sound reinforcement system for music concerts, theatre, sports games, and corporate events.

Alternatively, audio engineer can refer to a scientist or professional engineer who holds an engineering degree and designs, develops, and builds audio or musical technology working under terms such as electronic/electrical engineering or (musical) signal processing.

Research and development audio engineers invent new technologies, audio software, equipment, and techniques to enhance the process and art of audio engineering. They might design acoustical simulations of rooms, shape algorithms for audio signal processing, specify the requirements for public address systems, carry out research on audible sound for video game console manufacturers, and other advanced fields of audio engineering. They might also be referred to as acoustic engineers.

Audio engineers working in research and development may come from backgrounds such as acoustics, computer science, broadcast engineering, physics, acoustical engineering, electrical engineering, and electronics. Audio engineering courses at university or college fall into two rough categories: (i) training in the creative use of audio as a sound engineer, and (ii) training in science or engineering topics, which then allows students to apply these concepts while pursuing a career developing audio technologies. Audio training courses provide knowledge of technologies and their application to recording studios and sound reinforcement systems, but do not have sufficient mathematical and scientific content to allow someone to obtain employment in research and development in the audio and acoustic industry.

Audio engineers in research and development usually possess a bachelor's degree, master's degree or higher qualification in acoustics, physics, computer science or another engineering discipline. They might work in acoustic consultancy, specializing in architectural acoustics. Alternatively they might work in audio companies (e.g. headphone manufacturer), or other industries that need audio expertise (e.g., automobile manufacturer), or carry out research in a university. Some positions, such as faculty (academic staff) require a Doctor of Philosophy. In Germany a Toningenieur is an audio engineer who designs, builds and repairs audio systems.^{[citation needed]}

The listed subdisciplines are based on PACS (Physics and Astronomy Classification Scheme) coding used by the Acoustical Society of America with some revision.

Audio engineers develop audio signal processing algorithms to allow the electronic manipulation of audio signals. These can be processed at the heart of much audio production such as reverberation, Auto-Tune or perceptual coding (e.g. MP3 or Opus). Alternatively, the algorithms might perform echo cancellation, or identify and categorize audio content through music information retrieval or acoustic fingerprint.