Renault 32-04-054 Acoustic Verification of a Driver Station by Transparency Measurement in Combined Rooms

The aim of the “Renault 32-04-054 Acoustic verification of a driver station by measurement of transparency in combined chambers” standard, developed by the French automotive company Renault, is to characterize the entire cockpit in terms of its insulation against airborne noise, to determine the effect of each passage on the overall acoustic transparency of the cockpit, and to suggest corrective solutions where necessary. The goal is to ensure that each passage has a satisfactory level of transparency to ensure that the entire compartment is at a satisfactory level. Optimizing the compartment requires ensuring the homogeneity of all elements passing through the compartment.

This standard is also used to position each component according to its specifications and to position the entire cockpit according to specifications in terms of acoustic transparency. This standard is used to provide a database for transitions.

In principle, a broadband noise is propagated within the chamber. The acoustic fields within this chamber are considered diffuse. Measurements are performed at various points in the reception chamber. The test chamber must be capable of measuring a reference chamber unit with sufficient dynamics. The results should be expressed according to the differential insulation spectrum between emission and reception. This differential insulation spectrum is called gross or noise reduction insulation. A transmission loss is calculated between the emission chamber and the reception chamber. This calculation takes into account the measured surfaces and is used to compare results between different studies. Noise reduction is referred to as the noise reduction coefficient or sound transmission loss.

To ensure the analysis performed on combined compartments has true value, tests must be carried out on a complete unit according to the drawings. Each passage must be examined in a small compartment. The quality of the assemblies must be ensured.

The metal unit is prepared and cut for testing. The frame is attached. The metal unit is placed in the large compartment. Non-active surfaces are insulated. To inspect the side sections of the instrument panel and front pillars, it is necessary to move the cockpit into the compartment up to the front pillars. The windshield must be insulated by the engine, but not by the passenger compartment. All necessary parts for carrying out this program must be delivered to Renault. The suitability of the spark plugs and sealant lines is verified by Renault.

Within the framework of this standard, the following general measurements are carried out:

• Measurement in bare sheet configuration: This measurement serves as a reference for other measurements and the preparation of the specification draft.
• Measurement in reference partition configuration: This measurement involves assessing the efficiency of sound insulation components without any cuts.
• Measurement in the “bare sheet metal + basic sound insulation piece” configuration: The purpose of this measurement is to evaluate the effect of sound insulation piece cutouts.
• Measurement of the “complete cockpit without instrument panel” configuration: This measurement involves assessing the transparency of the compartment without the instrument panel and with all components installed.
• Measurement of the complete cockpit, including instrument panel configuration (original condition): This measurement consists of the following:
• Measuring the transparency of the partition with all components in place,
• Measuring the impact of the instrument panel on the overall transparency level.

In modern automotive engineering, where every hum, buzz, and whisper matters, Renault's internal standards act as conductors. The Renault 32-04-054 standard focuses on reducing noise, vibration, and harshness to create an optimal auditory environment for the driver. As vehicles evolve towards electrification and autonomous driving, such validations ensure the cockpit remains a sanctuary of focus and comfort, rather than a distracting element.

Acoustic verification means systematically testing and measuring the sound propagation, resonance, and damping of a vehicle's driving station. For Renault, this process is also an integral part of the user experience. Excessive noise from engine noise, road vibrations, or wind can lead to increased driver stress, decreased concentration, and long-term health problems such as hearing fatigue. The Renault 32-04-054 standard addresses these issues by defining criteria for sound pressure levels, frequency spectra, and transmission path analysis.

In the context of the driver's station, the focus is on the area surrounding the driver: from the headrest to the pedals, including interfaces such as the gear lever and infotainment controls. Verification ensures that materials such as instrument panel foams, door seals, and seat upholstery effectively reduce unwanted frequencies, typically below 65 dB at idle and highway speeds.

This standard is structurally divided into stages: design verification, prototype testing, and production approval. The measurement protocols are as follows:

• Microphone array setup: Three-axis microphones are positioned at ear reference points on a standardized dummy head to simulate human auditory perception. Measurements capture bipolar sound for subjective evaluation.
• Frequency range: Focus is placed on low-frequency bands (20–200 Hz) for building-related noise and mid-to-high frequencies (500–5000 Hz) for airborne disturbances such as HVAC hum.
• Test conditions: Sound power determination is carried out in semi-anechoic chambers or on the road with equipped vehicles, in accordance with the ISO 3744 standard.

The verification criteria have been defined as follows:

• Pass/fail thresholds: Sound pressure level limits vary depending on the vehicle segment. For example, compact cars like the Clio aim for a maximum of 60 dB at 100 km/h.
• Vibration-harshness integration: Uses accelerometers to correlate vibrations with audible rattling sounds, providing holistic noise, vibration, and harshness control.
• Material specifications: Critical panels necessitate the use of acoustic absorbers with absorption coefficients as low as 0,7, typically including porous foams or micro-perforated plates.

The following tests and simulations are required:

• Finite element analysis: Some software predicts modal resonances before considering physical structures by modeling acoustic cavities.
• Transfer path analysis: By identifying noise paths from the source (e.g., engine connections) to the receiver (driver's ear), it enables targeted countermeasures such as active noise cancellation.

In short, the Renault 32-04-054 standard verifies acoustics at the workstation level, thus not only complying with safety requirements but also enhancing the sensory experience.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its customers, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "Renault 32-04-054 Acoustic verification of a driver station by transparency measurement in combined rooms" standard.