Audiometric testing requires ambient sound below 35 dBA with frequency-specific limits

Evidence

When carrying out an audiometric test, local sound levels should be below the levels defined in BS EN ISO 8253–1, which are shown for the test frequencies in Figure 7.35. Generally, the local level should be below 35 dBA. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2344

Categorization

• DEFINE: Stakes out the quantitative threshold for test-room quiet, useful baseline for what ‘quiet enough to measure hearing’ actually means.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2344
• XREF: connects to: Recording studio background noise should approach the hearing threshold — Toole, Floyd E, Sound reproduction- the acoustics and…, 942; Normal hearing is operationally defined as a four-frequency average threshold below 25 dB HL. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4163; Pure tones are the standard audiometric stimulus because they are frequency-specific.