The Evolving World of Acoustics and Vibration TechnologiesCourtesy of the Museum for the Science of Sound, Kobayasi Institute of Physical ResearchPhoto by Yuki AkabaBarkhausen’s audiometer-type sound level meterOwned by the Museum for the Science of Sound, Kobayasi Institute of Physical ResearchThis audiometer-type sound level meter can be considered the ancestor of the Sound level meter in wide use today. Developed by Heinrich Barkhausen, a German physicist, this device measures noise level based on perceived loudness, not sound pressure. This device allowed subjects to hear ambient noise with one ear while simultaneously listening to a reference tone emitted by the device through a receiver with the other ear, and then the device compared the two to determine the level of noise. Upon its release in the 1930s, the product was first used to measure noise in factory environments, to evaluate the effectiveness of building soundproofing, and to take reverberation measurements in music halls. One notable application involved a project to assess background noise at London’s Royal Festival Hall. To a casual observer, this device may appear to be an antique instrument, and so the technology may seem outdated. But the method and the principles of auditory-based acoustic measurement adopted by Barkhausen are still used today in applications such as metal materials inspections.The World of Acoustics
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