Overview
ISO/TR 11688-1:1995 - "Acoustics - Recommended practice for the design of low-noise machinery and equipment - Part 1: Planning" is a Technical Report published by ISO to guide designers in incorporating noise control from the earliest planning stages through to final testing. It serves as an introductory, practical roadmap for understanding basic acoustic concepts and applying recommended practices to reduce noise emissions of machinery and equipment. The report focuses on methodical design, acoustic diagnosis, prototyping and measurement, and includes annexes with design rules, noise-control requirements, reporting templates and a bibliography.
Key topics and technical requirements
- Design process integration: Emphasises planning noise specifications in the project “clarification of task” and carrying noise objectives through conceptual design, detailed design and prototyping.
- Acoustic modelling & ranking: Divide machines into active (noise-generating) and passive (noise-radiating/transmitting) components; identify airborne, liquid-borne and structure-borne paths; rank dominant sources and sound-radiating surfaces.
- Noise mechanisms and causal chain: Understand generation → transmission → radiation for each source to target the most effective control measures.
- Control strategy hierarchy: Prefer source-control measures first, then path/transmission controls, then enclosure/absorption and surface radiation mitigation.
- Prototyping and testing: Use prototype measurements to quantify source strengths, verify noise-reduction measures and confirm compliance with requirements.
- Definitions & response types: Clarifies terms (periodic/tonal/broadband noise, force vs velocity excitation, quasi-static/resonant responses) to support consistent diagnosis and specification.
- Supporting material: Annexes summarise design rules, reporting information and bibliography for deeper technical references.
Applications and who should use it
ISO/TR 11688-1 is relevant for:
- Mechanical and product design engineers specifying low-noise objectives for motors, pumps, powerpacks, compressors, HVAC equipment and other machinery.
- Acoustic and vibration engineers conducting noise diagnosis, modelling and prototype testing.
- R&D teams and project managers embedding noise targets into the design lifecycle.
- QA, procurement and compliance staff preparing noise specifications and verifying that products meet client, regulatory or competitive requirements.
Practical uses include early-stage noise specification, concept selection based on acoustic trade-offs, targeted design changes to reduce structure-borne or airborne noise, and planning acoustic measurements during prototyping.
Related standards
The report references and complements measurement and declaration standards such as ISO 3744, ISO 3746, ISO 4871, ISO 9611, ISO 9614, ISO 11200 and ISO 11689, making it a planning-focused companion to standards for noise measurement and reporting.
Open preview (PDF)Acoustics — Recommended practice for the design of low-noise machinery and equipment — Part 1: Planning