Overview
EN ISO 11957:2009 (identical to ISO 11957:1996) is a CEN-adopted acoustics standard that specifies methods for the determination of sound insulation performance of sound‑protecting cabins. It defines both laboratory and in situ measurement procedures for complete cabins (not individual components) and applies specifically to cabins with a leak ratio ≤ 2%. The standard produces measurable the results such as sound pressure insulation (Dp), apparent sound pressure insulation (Dpa), A‑weighted values, and weighted single‑number ratings used to characterise cabin acoustic performance.
Key topics and requirements
- Scope and definitions: Terms such as cabin, sound pressure level (Lp), internal noise level (Lp,A), leak ratio and reverberant sound field are defined to ensure consistent measurement and reporting.
- Test environment selection: Laboratory conditions follow guidance related to reverberation rooms; in situ tests address realistic external sound fields.
- Instrumentation and calibration: Use of sound level meters, calibrators and octave/third‑octave filters in accordance with referenced IEC/ISO instrument standards is required.
- Laboratory measurements (Clause 6):
- Cabin mounting, location and boundary conditions specified.
- Measurement of sound pressure levels outside (reverberant room) and inside the cabin to compute Dp.
- In situ measurements (Clause 7):
- Microphone placement inside and outside cabin, handling of non‑diffuse fields and computation of apparent insulation (Dpa).
- Derived metrics:
- Apparent A‑weighted insulation (Dpa,A) and weighted single‑number insulation (Dpw) for simplified comparison and rating (per ISO 717‑1 method).
- Estimated cabin noise insulation for a specified noise spectrum (Annex A).
- Uncertainty and reporting:
- Clause on measurement uncertainty and detailed information to record and report (test object, conditions, instrumentation, acoustical data).
- Regulatory linkage:
- Informative annexes (ZA, ZB) explain relationships with EU Directives (e.g., machinery directives) for conformity assessment.
Applications and who uses it
- Acoustic engineers and test laboratories performing certified sound insulation tests on operator booths, machine enclosures, control cabins, recording booths and similar sound‑protecting cabins.
- Manufacturers verifying product noise attenuation performance during development or for conformity claims.
- Compliance officers and certification bodies assessing conformity with EU directives and national standards.
- Facility designers specifying cabins for industrial, transportation or broadcast applications where internal noise control is critical.
Related standards
- ISO 11957 (ISO original text, 1996)
- ISO 11546‑1 / ISO 11546‑2 (noise attenuation of enclosures)
- ISO 3741 (reverberation room sound power methods)
- ISO 717‑1 (rating of airborne sound insulation)
- Relevant IEC/ISO instrument standards (sound level meters, filters, calibrators)
Keywords: EN ISO 11957:2009, sound insulation, acoustics, cabins, laboratory measurements, in situ measurements, leak ratio, sound pressure level, A‑weighted insulation.
