Ship Sound Insulation Testing: Rw, R′w and DnT,w Explained

Room noise and sound insulation are different measurements

Room noise describes the sound that exists at a receiving position. Sound insulation describes the reduction in airborne transmission between a source space and a receiving space under controlled test conditions. A quiet receiving room does not prove a strong partition, and a noisy room does not prove a weak one.

A field assessment normally needs an artificial or controlled source in one space, spatially representative sound-pressure levels in both spaces, receiving-room background noise and reverberation information when required by the selected quantity.

Rw, R′w and DnT,w answer different questions

ISO 717-1 defines single-number quantities for airborne sound insulation based on frequency-band measurements. The exact symbol and criterion in the vessel specification should be retained; changing the metric after testing can change the commercial conclusion.

Confirm whether ISO 16283-1 fits the actual vessel spaces

ISO 16283-1 specifies field procedures for airborne sound insulation between rooms. Its published scope states room volumes from 10 m³ to 250 m³ and a frequency range from 50 Hz to 5,000 Hz. Small cabins, irregular volumes, coupled spaces and marine constructions may therefore need a project-specific applicability review.

• Confirm source and receiving room volumes.
• Check whether the sound field and measurement positions can satisfy the selected procedure.
• Identify narrow, highly absorptive, furnished or acoustically coupled spaces.
• Confirm whether the contract names ISO 16283-1, a legacy ISO 140 method, a class rule or another procedure.
• Agree how deviations, constrained positions and uncertainty will be reported.

ISO 140-4:1998 is withdrawn and ISO lists ISO 16283-1:2014 as the replacement. An older vessel contract may still reference a legacy method, so the contractual basis should not be silently changed.

Define the complete source/receiving test pair

Mark each pair on the vessel drawing and record the separating construction. A “bulkhead test” may actually include a door, ceiling void, raised floor, ventilation transfer path and multiple penetrations.

Field measurement evidence that should be controlled

1. Source spectrum and level: generate adequate sound across the required bands without overload or unsafe exposure.
2. Spatial sampling: use sufficient source and microphone positions to represent both rooms, not a convenient single point.
3. Background correction: measure receiving-room background and identify bands where the test signal is inadequate.
4. Reverberation evidence: measure or otherwise determine the correction required by the selected metric and method.
5. Geometry: document room volume, separating area where relevant and constrained positions.
6. Traceability: retain instrument identification, calibration evidence, settings, raw bands and calculations.
7. Deviations: state every departure from the method and its possible effect on the result.

Frequency-band results are essential for diagnosing weak performance. A single weighted number is useful for acceptance, but it can hide whether the weakness is low-frequency flanking, a mid/high-frequency air leak or a broadband construction problem.

Use the spectrum and inspection to distinguish leakage from flanking

Diagnostic methods can help locate paths, but the acceptance metric and diagnostic evidence should remain clearly separated in the report.

What the ship sound-insulation report should contain

• Vessel, project purpose, date, location and attendance parties.
• Selected method, rating quantity, edition and agreed acceptance criterion.
• Space-pair schedule, drawings, room volumes and construction descriptions.
• Source, receiving and background sound-pressure levels by frequency band.
• Reverberation/absorption evidence and any normalisation applied.
• Instrumentation, serial numbers, calibration traceability and field checks.
• Calculated frequency-dependent and weighted results.
• Position constraints, background limitations, deviations and uncertainty statement.
• Observed leakage/flanking evidence distinguished from confirmed defects.
• Prioritised corrective actions and repeatable verification scope.

Class, flag and contract review context

The required rating, method, supplier qualification and acceptance route depend on the class society, flag administration, notation, vessel specification, contract and attending surveyor. Confirm the basis before testing an ABS-, BV-, CCS-, CRS-, DNV-, IRS-, KR-, LR-, ClassNK-, PRS-, RINA- or Türk Loydu-classed vessel.

This guide discusses technical requirements and classed-vessel search intent. It does not claim that Vessel Doctor is an approved or recognised supplier and does not guarantee acceptance by a class or flag administration.

Five items to send before arranging the test

1. Vessel and attendance location/window.
2. Source/receiving room pairs marked on a drawing.
3. Separating construction, doors, penetrations and ventilation details.
4. Required metric, method, criterion and project purpose.
5. Review party, witness requirement, reporting deadline and repair/retest plan.

For general ship or cabin noise levels rather than transmission performance, use the onboard noise survey service. Attendance can be assessed across Asia-Pacific and worldwide, subject to access and availability.