General Information
Project data and location
Format: DDMMYYYY_Building
Location
Acoustic Parameters
Space configuration and characteristics
Requirements Analysis
Acoustic calculation results
0 W
Watts RMS @ 87dB
(Custom level)
(Custom level)
0 W
Watts RMS @ 78dB
(Organ reference)
(Organ reference)
0.0 s
RT60
Reverberation time
Reverberation time
Responsible person's signature
Acknowledgement by the person present during the assessment
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SPL Reference by Registration
Empirical measurements from pipe organs in church acoustics (RT60 1.6-1.8s, 300-400 seats). Data from Hall (1993).
| Registration | SPL (dB) | dB(A) |
|---|---|---|
| Soft stops (Dulciana, Unda Maris) | 60-66 | 53-65 |
| Flutes (Rohrflöte, Bourdon) | 70-76 | 66-70 |
| Principal 8' alone | 80-84 | 74-78 |
| Principal chorus (8+4+2) | 83-87 | 77-84 |
| Full chorus + mixtures | 87-90 | 84-88 |
| Full organ (Sforzando) | 90-92 | 87-90 |
Dynamic range: ~35 dB from pp to fff. One dynamic step ≈ 3-4 dB.
Note: dB(A) correlates better with perceived loudness.
Methodology
Reference Criterion — Phelps (2003)
• Principal 8': 76-80 dB (optimal: 78 dB) for adequate liturgical volume
• Empirical validation: Hall (1993) measured 74-78 dB(A) for Principal 8'
Multi-band Acoustic Model
• RT60 = 0.161 × V / A (Sabine formula)
• SPL = SWL + 10·log₁₀(Q/4πr² + 4/R) — direct + reverberant field
• 3-band model: 125 Hz (low), 500 Hz (mid), 2000 Hz (high)
• Liturgical optimum: RT60 = 2.0-2.5s for organ
Frequency-dependent Absorption Coefficients
• Stone: α = 0.02/0.04/0.05 (low/mid/high)
• Wood: α = 0.15/0.10/0.07 (panel resonance at low freq)
• People: 0.25/0.45/0.55 Sabines/person
• Traditional glass: α = 0.25/0.10/0.05
Architectural Factors
• Lateral reflections: narrow rooms (W/L < 0.4) enhance dynamics 2-5 dB
• Dome: +25% power | Cruciform: +20% power
• Speaker efficiency: 0.5% (low), 1% (mid), 1.5% (high)
• +3 dB → double power | +10 dB → 10× power
• Principal 8': 76-80 dB (optimal: 78 dB) for adequate liturgical volume
• Empirical validation: Hall (1993) measured 74-78 dB(A) for Principal 8'
Multi-band Acoustic Model
• RT60 = 0.161 × V / A (Sabine formula)
• SPL = SWL + 10·log₁₀(Q/4πr² + 4/R) — direct + reverberant field
• 3-band model: 125 Hz (low), 500 Hz (mid), 2000 Hz (high)
• Liturgical optimum: RT60 = 2.0-2.5s for organ
Frequency-dependent Absorption Coefficients
• Stone: α = 0.02/0.04/0.05 (low/mid/high)
• Wood: α = 0.15/0.10/0.07 (panel resonance at low freq)
• People: 0.25/0.45/0.55 Sabines/person
• Traditional glass: α = 0.25/0.10/0.05
Architectural Factors
• Lateral reflections: narrow rooms (W/L < 0.4) enhance dynamics 2-5 dB
• Dome: +25% power | Cruciform: +20% power
• Speaker efficiency: 0.5% (low), 1% (mid), 1.5% (high)
• +3 dB → double power | +10 dB → 10× power
Sources
• Hall, D.E. (1993). Musical dynamic levels of pipe organ sounds. Music Perception, 10(4), 417-434. doi:10.2307/40285581
• Pätynen, J. et al. (2014). Concert halls with strong lateral reflections enhance musical dynamics. PNAS, 111(12), 4409-4414. doi:10.1073/pnas.1319976111
• Phelps, L.I. (2003). Organ Power Requirements. Allen Organ Company.
• Pätynen, J. et al. (2014). Concert halls with strong lateral reflections enhance musical dynamics. PNAS, 111(12), 4409-4414. doi:10.1073/pnas.1319976111
• Phelps, L.I. (2003). Organ Power Requirements. Allen Organ Company.