05 · Method
Method and data
How every number on this site was produced. The site reads a JSON export of the analysis workbooks; ratings are re-derived with the same ISO 717-1 fit and checked against the workbook at build time.
Quantities
- R
- Sound reduction index per third-octave band, from the 2270's R′ with the partition area re-referenced to the 960 × 960 mm specimen: 10 log₁₀(0.9216 / 1) = −0.35 dB on every band.
- Rw (C; Ctr)
- ISO 717-1 single-number rating. The reference curve is shifted in 1 dB steps to the highest position where the sum of unfavourable deviations over 100–3150 Hz is ≤ 32 dB, and Rw is read at 500 Hz. C and Ctr are the spectrum adaptation terms for pink noise and urban traffic noise.
- ΔR, ΔRw
- ΔR is the band-by-band difference R − R(baseline). ΔRw fits the ISO 717-1 curve to that difference directly, which is not the same as Rw(test) − Rw(baseline): each separate fit settles on its own worst bands and rounds on its own.
- Mean R
- The arithmetic mean of R over the 16 rating bands, 100–3150 Hz.
- T60
- Receiving-room reverberation time, from the 2270's T20 Room row.
- αs
- ISO 354 difference method on the receiving room: A_T = 0.161 V (1/T − 1/T_empty), αs = A_T / S, with V = 180 m³, S = 0.9216 m² and the empty room as baseline. Shown over the ISO 354 range, 100 Hz–5 kHz.
Analysis settings
- STL area correction
- -0.35 dB = 10 log10(0.9216 / 1); the master carries every R' referenced to a partition area S = 1 m2 (the 22 Sep jobs were set up with 11.5 m2 and are re-referenced by consolidate_acoustics.py)
- Rw / C / Ctr
- ISO 717-1 over 100-3150 Hz, unfavourable deviations <= 32 dB
- Delta Rw
- ISO 717-1 fitted to the difference curve R - R(Project001) taken band by band, not Rw(test) - Rw(baseline)
- Sabine method
- ISO 354 difference method on the receiving room T20: A_T = 0.161 V (1/T - 1/T_baseline), alpha_s = A_T / S
- Sabine baseline
- EmptyRoom (Empty Room | No Insulation | No MLV)
- Room volume
- 180 m3
- Specimen area
- 0.9216 m2
- Attribute fixes
- Project031: {'Hole Diameter (mm)': 12.0}
- Excluded tests
- Project059, Project063
- Repeat tests
- Project071 repeats Project003; Project074 repeats Project069; the original of each pair is the one in the sweeps and insight charts, both are in Metrics
- Source workbook
- Master_Acoustics_Consolidated.xlsx
Download the data
acoustic_metrics.csv
65 tests: attributes, Rw, C, Ctr, ΔRw, mean R and R per band.
acoustics.jsonEverything the site uses: R, T60, αs, A_T per band, comparison groups, method notes.
ISO 717-1 reference valuesdB, 1/3 octave
| Band | 100 | 125 | 160 | 200 | 250 | 315 | 400 | 500 | 630 | 800 | 1k | 1.25k | 1.6k | 2k | 2.5k | 3.15k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Reference curve | 33 | 36 | 39 | 42 | 45 | 48 | 51 | 52 | 53 | 54 | 55 | 56 | 56 | 56 | 56 | 56 |
| C spectrum (No. 1) | -29 | -26 | -23 | -21 | -19 | -17 | -15 | -13 | -12 | -11 | -10 | -9 | -9 | -9 | -9 | -9 |
| Ctr spectrum (No. 2) | -20 | -20 | -18 | -16 | -15 | -14 | -13 | -12 | -11 | -9 | -8 | -9 | -10 | -11 | -13 | -15 |