Padded Sounds: S. S. Stevens Conducting Speech Intelligibility Tests, Harvard University, circa 1943

Excerpt from Site 02 of the work-in-progress Padded Sounds: a practice-based inquiry into aural affordances of anechoic chamber techniques. This excerpt examines the audible contexts of communication intelligibility and speech masking conducted at the Psycho-Acoustic Laboratory (PAL) and Electro-Acoustic Laboratory (EAL) anechoic chambers at Harvard University in the 1940s. Among the sounds included in the excerpt are the reconstruction of an obsolete analogue audio pulse and amplified thermal noise. The latter—directly tapped from a chunk of raw graphite—approximates sounds of a custom carbon-noise generator that served as the backbone for bomber aircraft noise simulations at the Harvard labs. The speech sample, from Adam Smith’s book The Wealth of Nations (1776), was one of the original test signals employed in the masking tests.

Recordings for Site 02 were completed in another anechoic facility (stemming from these original wedge-padded designs at PAL / EAL), located at Delft University of Technology, the Netherlands. Of particular interest here are the audible qualities of historical sonic techniques that were in fact never recorded. Results issuing from the chamber took the form of mute data conveyed through spectral graphs and statistical charts. Listening today through such set-ups, with a different set of questions at hand, is itself an experiment in retroactive hearing rather than a stringent set of test reconstructions.