ISO 6798-3:2022

Overview

ISO 6798-3:2022 specifies an in situ survey method to determine the sound power level of reciprocating internal combustion engines using measured sound pressure. Applicable to engines covered by ISO 3046-1 (and other engines where no suitable standard exists), this Part 3 method is intended for on-site surveys with accuracy grade 3 and produces A‑weighted sound power values. The standard defines the test environment, instrumentation, measurement procedures, uncertainty assessment and reporting required to characterize engine noise in real installation conditions.

Key Topics

• Scope and applicability: Reciprocating internal combustion engines used for general purposes (see ISO 3046-1).
• Test environment: Measurement surfaces that envelop the noise source and consideration of reflecting planes (ground or multiple reflecting planes).
• Instrumentation and calibration: Requirements for sound level meters, filters and calibrators (class/grade requirements and calibration procedures).
• Measurement layout: Definition of the measurement surface, measurement distance, microphone positions, and criteria for position adequacy.
• Reference sound source (RSS) methods: Use of RSS and permitted methods such as substitution, top‑up and juxtaposition for in situ verification and comparison.
• Background noise correction and criteria: Minimum differences between source and background levels (e.g., ΔL criteria) and maximum allowed corrections (K) to ensure valid results.
• Calculation and uncertainty: Procedures to compute surface time‑averaged sound pressure levels, corrections for background noise, conversion to sound power level, and stated measurement uncertainty (A‑weighted reproducibility upper bound ~4.0 dB).
• Reporting: Required test report content including test conditions, instrumentation, measurement data and uncertainty.

Applications

• Field surveys to quantify engine noise for compliance checks, contract verification, or performance validation.
• Comparative assessments of noise radiation between engine types, installations or retrofits.
• Input data for noise control engineering and prediction of sound pressure levels at specified receiver locations.
• Acceptance testing and communication of acoustic information among manufacturers, installers and end users.

Who should use this standard

• Acoustic consultants and test laboratories performing on‑site engine noise surveys.
• Engine manufacturers and OEMs documenting radiated noise for product declarations.
• Facility engineers, installers and procurement teams verifying contractual noise limits or planning mitigation measures.
• Regulators and certification bodies requiring standardized in situ sound power assessment.

Related standards

• ISO 6798-1 (Engineering method) and ISO 6798-2 (Survey method)
• ISO 3046-1 (Engine performance declarations)
• ISO 6926, IEC 60942, IEC 61672-1, IEC 61260-1 (reference sources, calibrators, meters and filters)

Keywords: ISO 6798-3, sound power level, reciprocating internal combustion engines, in situ survey method, sound pressure measurement, acoustic measurement, background noise correction, reference sound source.