A finger blocks ~30 dB but leaves low frequencies below 200 Hz unattenuated

Evidence

Several repeated measurements found a consistent attenuation of ~ 30 dB across most of the frequency spectrum, but progressively declining at low frequencies to negligible levels at 200 Hz and below. Assuming this measurement gives a reasonably accurate reflection of the change in cochlear excitation when a human listener blocks the meatus, the question arises whether this residual sound might be sufficient to support summation. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1525

Categorization

• XREF: Connects to occlusion attenuation data; a natural fact about how the ear plugs physically work.