Academy Curve

sound

Also known as: Standard Electrical Characteristic of 1938

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Last updated

July 23, 2026

Quick Summary

The "Academy Curve" refers to a specific treble-cut filter used in monaural sound systems for motion pictures. This curve was implemented to reduce high-frequency noise, such as ground noise on optical soundtracks and hiss from vacuum tube amplifiers. Frequencies above 8,000 hertz (Hz) were "rolled off".1

While this filter was effective in its time, advancements in noise reduction technology, like Dolby, and the transition to solid-state amplifiers have allowed for a wider frequency range, up to about 12,000 Hz, and generally louder sound reproduction. The human ear has a vast dynamic range, responding non-linearly to both frequency and intensity, with a threshold of hearing around 20 Hz to 20,000 Hz.12

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motion-picture technology
Sound reproduction
…Electrical Characteristic of 1938, or Academy Curve, so that frequencies above 8,000 hertz (Hz) are “rolled off.” This practice dates from an era when sound tracks had a large degree of ground noise and vacuum tube amplifiers produced an audible hiss concentrated in the upper frequencies. A treble boost is…
Read More
…Electrical Characteristic of 1938, or Academy Curve, so that frequencies above 8,000 hertz (Hz) are “rolled off.” This practice dates from an era when sound tracks had a large degree of ground noise and vacuum tube amplifiers produced an audible hiss concentrated in the upper frequencies. A treble boost is…
Read More