Airborne sound insulation — STC and Rw testing
Airborne sound insulation is measured by building the specimen into the aperture between two reverberation rooms, driving one side and measuring what arrives at the other. The result is the sound reduction index R, and every single-figure rating a specification quotes — Rw, STC — is derived from it.
What you get back
- Sound reduction index R in one-third octave bands, to ISO 10140-2 — the underlying curve.
- Weighted sound reduction index Rw with the spectrum adaptation terms C and Ctr, to ISO 717-1 — Rw (C; Ctr) is what European and most Asian specifications quote.
- Sound Transmission Class (STC), to ASTM E413, from transmission loss measured to ASTM E90 — what North American specifications quote.
- Transmission loss TL in one-third octave bands, to ASTM E90, where the specification wants the curve rather than the rating.
- Both ISO and ASTM ratings from a single test where the specimen and mounting allow it — worth asking about before you book two tests.
Rw and STC are not interchangeable and do not convert reliably between each other. If a specification names one, test to that one. Where a product is sold into both markets it is usually cheaper to ask for both ratings at the outset than to repeat the test later.
Building elements and products we test
- Doors and door sets — timber, steel, acoustic and fire-rated, tested as a complete set with frame and seals.
- Windows, glazing units and curtain wall panels — single, double and laminated glazing, fixed and openable.
- Partition systems — gypsum board on stud, blockwork, demountable and glazed office partitions.
- Facade and cladding panels, sandwich panels and metal composite systems.
- Acoustic louvres, ventilation elements and small building components.
- Floor and roof build-ups, and any assembly the specification treats as a single element.
Turnaround and logistics
- Typical turnaround
- About two weeks from receipt of a complete specimen and an agreed scope
- Urgent work
- An urgent route is available — tell us the date you are working to at enquiry, not after booking
- Before you ship
- Confirm specimen size, mounting and packing first — see sample requirements
- Report language
- Reports issued in English; correspondence in Thai or English
Full-size specimens mounted in the test aperture between two decoupled reverberation rooms. Reported per one-third-octave band and rated as STC to ASTM E413 or Rw with C and Ctr to ISO 717-1.
- Wall and partition systems, including drywall and modular partitions
- Doors and door sets, including acoustic doorsets
- Windows and glazing systems
- Acoustic barriers and enclosure panels
- Composite construction products
Test facility
- Configuration
- Two decoupled reverberation rooms
- Frequency range
- 100–5,000 Hz, one-third-octave bands
- Reported quantities
- TL or R per band, STC (ASTM E413), Rw + C + Ctr (ISO 717-1)
Every specimen is scanned before we measure
A gap of a millimetre where the specimen meets the test aperture can cost several decibels in the upper bands, and would understate what your product actually achieves. Before the official measurement we scan the installed specimen with an acoustic camera to confirm the mounting is sound. If it is not, we re-install and re-scan. Included as standard.