Off-axis measurement data was recognized as valuable from early analog systems
Evidence
Following the decision to commit to the loudspeaker investigations, the NRCC anechoic chamber was reconfigured for convenient loudspeaker measurements, starting with a rotating platform allowing full 360° measurements at 2 m distance. In the beginning the data were acquired using the then state-of-the-art Brüel & Kjær analog measurement system, generating accurate ink plots on graph paper. Post-processing of data was very limited, and manual, but despite the difficulties, one could see that off-axis measurements were valuable data. In 1983 the analog system was replaced by a custom hybrid analog/digital system controlled by a DEC PDP-11/03 computer that permitted storage and post-processing of data acquired with 1/20-octave resolution. Low-frequency calibration of the chamber was then possible. It was a breakthrough. — Toole, Floyd E, Sound reproduction- the acoustics and…, 164
Categorization
Category: Factual Claims
- DEFINE: Establishes the 1/20-octave resolution milestone — the measurement precision that enabled low-frequency calibration.