Both workflows use assigned acoustic materials, but interpret their coefficients according to the calculation method. Statistical analysis uses equivalent absorption area; ray analysis uses the fraction of incident energy absorbed at a surface.
From Revit constructions to acoustic assignments#
Revit construction and material names need acoustic assignments. Acouso-ROOM connects constructions to acoustic materials; users can review project baselines and refine individual rooms with finishes and treatments. Similar names do not establish equivalent acoustic inputs.
Review Generic fallback areas and resolve missing or conflicting assignments before relying on results. Suggested assignments are candidates for review against the actual construction and project specification.
Absorption and exposed area#
Equivalent absorption area
Equivalent absorption area combines the exposed area and effective absorption of each assigned surface in an octave band.
- A
- Equivalent absorption area (m²)
- Sᵢ
- Exposed area of surface or assigned patch i (m²)
- αᵢ
- Effective band absorption coefficient for that patch (dimensionless)
C. F. Eyring (1930), Reverberation Time in “Dead” Rooms.
Absorption varies by frequency, mounting and installation. Record the source of material data and the test or mounting conditions where available. Equivalent absorption measured in a reverberation room can exceed the specimen's geometric area; a value above one is not a claim that a surface absorbs more than all incident energy.
| Use | Effective coefficient interpretation |
|---|---|
| Material-library input | The material editor accepts band values from 0 to 2. |
| Sabine / equivalent absorption area | Equivalent absorption coefficients above one can contribute to area × coefficient. |
| Norris–Eyring | The area-weighted mean is limited below one for the logarithm. |
| Millington–Sette | Each contributing patch coefficient is limited below one for the logarithm. |
| Ray surface energy balance | Ray energy absorption coefficients are between zero and one; values above one are limited to one for the energy calculation. |
Ray analysis uses absorption coefficients between zero and one. Values above one are limited to one for the energy calculation. Missing frequency bands may be inferred from available material data, and missing scattering data uses analysis defaults. Review inferred or fallback material properties when assessing the results.
Scattering#
Scattering describes how reflected energy is redistributed rather than absorbed. It depends on surface structure, frequency and the data's definition. Check the scattering basis as well as absorption; a generic setting is not evidence of measured performance for a specific construction.
Source spectrum and directivity#
Ray source spectra distribute sound among frequency bands. Source orientation and directivity affect the energy reaching each position. Generic directivity presets are illustrative and are not measured loudspeaker data.
In absolute source mode, the supplied octave-band levels define the source’s on-axis sound pressure level at a reference distance of 1 m. Predicted receiver levels use this saved source reference. Relative source mode does not establish absolute SPL.
Changing a spectrum or directivity can change both band levels and derived metrics.
Input review checklist#
- Review exposed baseline, finish and treatment areas without double counting.
- Check coefficients in every relevant band and distinguish entered from inferred data.
- Record material provenance and installation conditions.
- Resolve Generic areas, missing references and assignment conflicts.
- Confirm source spectrum, orientation, directivity and level basis.
- Save or record the inputs needed to interpret the result.