stereo equipment that boosts the sound level called an integrated amplifier
stereo equipment that lets one adjust the frequency response of the sounds called a graphic equalizer
a machine for collecting low volume sounds and amplifying them, called parabolic reflector
a pulse generator used for echo sounding in sonar
a tape recorder that uses wire as the recording medium, called wire recorder
an office machine for transcription that records words spoken into it and then reproduces them, called Dictaphone
a spectrograph for acoustic spectra
a trumpet-shaped acoustic device to intensify and direct the human voice
stereo equipment that combines the main and pre-amplifiers