An ancient Malta chamber amplifies only deep male voices at 90 hertz.

Evidence

If a man speaks there slowly in a deep voice, the low-frequency components of his speech will be considerably amplified and a deep, ringing sound will fill not only the oracle chamber itself, but also the circumjacent rooms with an awe-inspiring sound. (A child or a woman will not be able to produce this effect, the fundamental pitch of their voices being too high to activate the resonator.) — Schafer, Murray R, The Soundscape- Our Sonic Environment…, 715

Categorization

• XREF: Echoes the later Helmholtz resonator descriptions and the reader’s interest in acoustic engineering of sacred spaces.
• FICTION: An oracle room that only answers deep male voices is a ready-made story engine about gendered access to the divine.
• corroborated: 2 independent passages support this claim — Schafer, Murray R, The Soundscape- Our Sonic Environment…, 715