Varying source strength randomly and logging ambient noise guards against biased sound readings.

Evidence

At any particular frequency the source strength was varied 10 dB or more in a random order unknown to the analyzer. Each observation included a measurement of ambient noise level. — Donald Aylor, Noise Reduction by Vegetation and Ground, 38

Categorization

• XREF: The randomized, blind-to-analyzer source-strength design is a solid field-method exemplar that could transfer to soundscape-ethnography recording protocols. — connects to: Subjects bias adjustment experiments by setting sounds louder for good audibility

Broader Connections

• Subjects bias adjustment experiments by setting sounds louder for good audibility #corroborates (0.75)