Acoustic Engineering: Target Frequencies, Chamber Dimensions, and Resonance Modes

Primary: 110Hz (Malta Hypogeum, King's Chamber)
→ Deactivates language center (Time & Mind, 2008)
→ Shifts prefrontal to right-side processing
Secondary: 7.83Hz (Schumann fundamental)
→ Theta brainwave entrainment
→ Global phase-locking signal
Tertiary: 10-14Hz (alpha band)
→ Calm alertness, social synchrony

f = c / (2L) where c = 344m/s (speed of sound)
For 110Hz: L = 344 / (2 × 110) = 1.56m
A chamber dimension of ~1.56m supports 110Hz
fundamental standing wave.
For 86Hz: L = 344 / (2 × 86) = 2.0m
For 55Hz: L = 344 / (2 × 55) = 3.13m

f = (c / 2π) × √(A / (V × L_eff))
c = 344m/s, A = neck area, V = cavity volume,
L_eff = neck length + 1.6r (end correction)

Design for 10Hz Helmholtz resonance:
V = 30m³ (chamber ~3.1m cube)
L_eff = 2m (passage), A = 2m² (1.4m × 1.4m)
f = 54.8 × √(2 / (30 × 2)) = 54.8 × 0.183
f = 10.0Hz ✓

Limestone chambers: Q = 50-200
Granite chambers: Q = 100-500
At Q = 100, acoustic energy at resonance is
amplified 100× relative to broadband.
After 100 cycles (~10s at 10Hz):
amplitude = Q × input ≈ 100× source level.

Malta Hypogeum: >4 seconds
King's Chamber: ~8 seconds (granite)
Design target: 4-8 seconds RT60
Material: dense limestone or granite (low absorption)