Sound absorption coefficient database

The database covers 14 material categories: mineral wool, wood and wood wool, gypsum and perforated boards, metal tiles, foams, textiles and curtains, acoustic plaster, stone and concrete, glass and foils, felt, and audiences and seating. Each entry carries the frequency-dependent absorption coefficient αs per one-third-octave band from 100 to 5,000 Hz, the octave values αp, the weighted coefficient αw and the absorption class A to E to ISO 11654, plus mounting type, thickness, air gap and test build-up.

4,373 measured variants spread across 2,004 products because many products were measured in several build-ups: a different thickness, a different air gap, a different mounting. A variant is always a separate measurement. 3,766 variants carry one-third-octave values and 3,956 an αw; across all rated variants the median is αw 0.65. 740 variants reach class A, which is 18.7 percent (as of 12 September 2026).

Beyond room acoustics the database lists 16 building components with measured sound insulation: partitions, ceilings, floor build-ups and noise barriers with Rw, Ln,w, Dn,f,w and DLR from test reports to ISO 10140, ISO 10848 and EN 1793.

Three sources, each visibly labelled. First, the absorber database of the Physikalisch-Technische Bundesanstalt: 1,746 reverberation-room measurements that the PTB compiled over decades from test reports and technical literature, covering 100 brands such as Ecophon, Rigips, Knauf, Hunter Douglas and pinta acoustic. These are reference values, not current manufacturer claims, and every page marks them as PTB reference.

Second, test reports that manufacturers provide for their listed products: 1,279 measured variants name the laboratory and 1,147 carry a report number, 64 different laboratories in total, among them MFPA Leipzig, ift Rosenheim, Fraunhofer IBP and the Austrian ÖAL. Third, datasheet values without a report behind them; they are shown in grey and do not count towards the absorption class. The tier of every value is printed next to it on the product page: accredited, third-party lab, configuration test, material test, datasheet or reference value.

Not in the database: manipulated or stitched-together test reports, values without a stated build-up, and manufacturer claims that contradict an existing measurement. In doubt a value stays grey or is not published.

All absorption values come from the reverberation-room method of ISO 354. A specimen of 10 to 12 m² is installed in a reverberation room; the shortening of the reverberation time compared with the empty room yields the equivalent absorption area and from it the absorption coefficient αs per one-third-octave band. The mounting type of ISO 354 Annex B is part of the result, type A directly on the substrate, type E with a defined cavity: below 500 Hz the air gap changes the value more than the material does.

From αs follow the octave values αp and the single-number weighted coefficient αw to ISO 11654, from which the absorption class is derived. One-third-octave values above 1.0 are normal, they arise from diffraction at the specimen edges; αw, by contrast, is capped at 1.00. Object absorbers such as baffles or screens yield an equivalent absorption area Aobj per piece instead of αs. The method is explained in the article on reverberation-room measurement, the quantities in the article on the sound absorption coefficient.

The search filters across manufacturers by αw, absorption class, material category, mounting type, build-up depth, fire class and EPD, and by minimum values per frequency band: if you need at least 0.5 at 125 Hz, you only see measurements that meet it. Results can be overlaid as curves, saved to projects and exported as Excel or JSON.

For simulation and your own tools there is a read API with an OpenAPI description and an MCP server through which Claude and ChatGPT search the database directly. The reverberation time calculator to DIN 18041 uses the same measurements. Planners, acousticians and architects use search, comparison and export free of charge, permanently.

Manufacturers list their products with test reports and reach the acoustic consultancies, planners and architects who look values up here. Anyone without a measurement yet can commission one through the measurement service to ISO 354 in a reverberation room, including mounting and test protocol. Process and requirements are on the page for manufacturers.