Bruel and Kjaer Frequency Response Tracer Type 4707, a precision electronic instrument designed to analyse and display the frequency response of audio and vibration systems. Instruments of this type were used in acoustic laboratories, telecommunications research and engineering environments to evaluate amplifiers, transducers and measurement equipment across defined frequency ranges.
Manufactured by the Danish company Bruel and Kjaer, known for high quality acoustic and electronic test equipment, it formed part of professional measurement systems. Prior to digital spectrum and computer based analysis; 1960s–1970s.
