Technical Column

 Indoor Coast-by

2025年5月23日

Standard for Indoor Noise Testing of Tires Using a Drum Test Machine

In 2023, ISO 20908:2023 was introduced as a new method for indoor testing of tire noise emissions.

“Tyre sound emission test. Methods of drum”

Compared to the existing outdoor measurement method ISO 13325, this ISO standard appears to be the first edition specifically for indoor measurements.
Similar to ISO 362-1, 362-2, and 362-3, which measure vehicle pass-by noise, this new standard was established to enable testing that was previously limited to outdoor environments to now be conducted indoors.

There is a growing trend toward performing vehicle noise measurements indoors through “indoor pass-by” methods, as opposed to traditional outdoor test tracks.

Outdoor tests have been subject to weather conditions, such as rain and strong winds, which restricted testing to specific times. However, with the introduction of ISO 20908, efficient and flexible indoor testing has become possible.
That said, constructing an indoor testing facility requires a wide range of equipment, including a drum system, a semi-anechoic chamber, and precise temperature control.
Additionally, it is necessary to properly address the sound components of rolling noise based on ISO 10844.

As a manufacturer of anechoic chambers, we are capable of proposing facility designs that meet the required specifications, including temperature-controlled environments and microphone array layouts based on the inverse square law.
Temperature control is managed in a manner similar to a thermal chamber, with insulation applied to the walls, ceiling, floor, and doors of the anechoic room, combined with an advanced HVAC system.

While the temperature ranges required by ISO 362-3 and ISO 20908 may differ, the measurement methods based on the inverse square law are similar to those defined in ISO 362-3.
Furthermore, considering the relationships with other standards, the newly established “Indoor Coast-by” evaluation method now enables quantitative assessment of tire coast-by noise at any time.

Drawing on our extensive experience and knowledge, we are committed to designing rooms and measurement systems that comply with these latest standards.
Please feel free to contact us for more information.

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