Acoustic Phonetics (definition)
A particular field of phonetics which is concerned with the specifics of sound once it is produced. Acoustic phonetics focuses on elements of sound such as frequency, duration, intensity etc. Sound can be recorded and then represented on a chart called a spectrogram, which helps visualize these elements. Depending on the look of each sound's spectrogram phoneticians can tell what type of sound was being made, specifics about how it was produced, and how a hearer might perceive the sound.