The 20th session of the Task Force on Vehicle Sound convened on 14 April 2026. The session adopted the draft agenda and reviewed the 19th session report with a minor correction. The cross-matrix, defined in 2021 to assess traffic noise reduction policies through traffic scenarios and models, was rediscussed. A model based on RD-ASEP monitoring data was presented, showing significant deviations from EU-CNOSSOS predictions. Additional data are needed for M₃/N₃ and L-category vehicles. Extension of the cross-matrix to L-categories was proposed, utilising data from UN R41-06 RD-ASEP. A subgroup was established to develop scenarios, particularly for L-categories, and review available models. The next meeting is scheduled for 9 June 2026.

NEFOM and S.O.S. represent over 1 million European citizens experiencing noise from light vehicles inconsistent with Certificate of Conformity figures. The LENS project conducted 2300 measurements of 2300 vehicles, finding measured noise levels in practice much higher than type approval, sometimes reaching 100 dB(A). The A-filter used in Certificates of Conformity is unsuitable for noise levels above 70 dB and does not represent human perception. Sound limits for motorcycles have not changed since 2015 and remain too high. The document requests further improvements to RD-ASEP testing, replacement of the A-filter with a C-filter, and significant reduction of sound level limits for motorcycles.

Proposal to amend paragraph 8.4 to allow Conformity of Production tests to use different acceleration values when environmental conditions or rider mass prevent achieving the reference acceleration (a_wot,ref ) with the same gear used during type approval testing.

Proposal to clarify the gear selection procedure pursuant to the amendment to allow deviation from the reference acceleration a_wot,ref requirement for Conformity of Production tests.

Proposal to clarify the gear selection procedure pursuant to the amendment to allow deviation from the reference acceleration a_wot,ref requirement for Conformity of Production tests.

IWG RD-ASEP status report to GRBP-82 in September 2025 after the 8th session. RD-ASEP for UN R51 work packages completed with 507 vehicle files delivered in April 2025. IWG recommends no monitoring requirements approval without corresponding collection, analysis, and reporting mechanisms in place. Financing of WP3 required from additional contracting parties or reduced scope planned. RD-ASEP for UN R41 activity closed with GRBP adoption of proposals based on ECE/TRANS/WP.29/GRBP/2025/4, ECE/TRANS/WP.29/GRBP/2025/6, and ECE/TRANS/WP.29/GRBP/2025/7 as amended.

Proposal to clarify the gear selection procedure pursuant to the amendment to allow deviation from the reference acceleration a_wot,ref requirement for Conformity of Production tests.

Proposal to

1. Update the RD-ASEP limit line following the revisions of the test procedures implemented by the 05 series of amendments,
2. Clarify the application of the Annex 7 ASEP testing conditions of motorcycles,
3. Strengthen provisions against test defeating,
4. Facilitate Conformity of Production testing, and
5. Correct the communication document.

Proposal to

1. Clarify the application of the Annex 7 ASEP testing conditions of motorcycles,
2. Strengthen provisions against test defeating,
3. Facilitate Conformity of Production testing, and
4. Correct the communication document.

Proposal to strengthen provisions against test defeating and to facilitate Conformity of Production testing.

Informal document from the Informal Working Group on Real Driving – Additional Sound Emission Provisions replacing the formal proposal to update the RD-ASEP limit line following revisions of the test procedures implemented by the 05 series of amendments.

Informal document from the Informal Working Group on Real Driving – Additional Sound Emission Provisions to replace the formal document proposing a Supplement to the 05 series of amendments to clarify the application of the Annex 7 ASEP testing conditions of motorcycles.

Draft informal submission to the 81st (February 2025) GRBP session intended to supersede the formal submission GRBP/2025/4 (to clarify the application of the Annex 7 ASEP testing conditions of motorcycles).

Motorcycle RD-ASEP informal group proposal to set a new limit line pursuant to changes in the test procedures introduced in the 05 series of amendments, superseding the formal submission GRBP/2025/5.

Proposal to clarify the application of the Annex 7 ASEP testing conditions of motorcycles.

Proposal to update the RD-ASEP limit line following the revisions of the test procedures implemented by the 05 series of amendments.

Proposal to strengthen provisions against test defeating and to facilitate Conformity of Production testing.

Proposal to strengthen provisions against test defeating, to facilitate Conformity of Production testing, and to correct the communication document.

Control range of CVT and limit value at high PMR & high rpm

Proposal prepared by the experts from the IWG RD-ASEP in order to clarify the application of the Annex 7 ASEP testing conditions of motorcycles.

IWG RD-ASEP has two parts:
A) RD-ASEP for UN-R51, to develop a mandatory procedure after the
monitoring phase
B) RD-ASEP for UN-R41: ASEP second step, to develop stricter ASEP limit
curves

Working draft interpretation provisions to clarify the application of the Annex 7 ASEP testing conditions of motorcycles.

Outlook and progress of the IWG RD-ASEP R41 amendment proposal for a new 06 series of amendments to UN Regulation N°41

Proposal to permit the use of state-of-the-art test tracks per the latest standard ISO 10844:2021.

Proposal to allow use of state-of-the-art test tracks per the latest standard ISO 10844:202

Replace the proposal for Supplement 3 of the 05 Series of amendments

Proposal to replace the Supplement 11 of the 04 Series of amendments

Proposal to transition test facilities from ISO 10844:2014 to ISO 10844:2021 by January 2029.

Proposal to update the terms of reference for the Informal Working Group on Real Driving-Additional Sound Emission Provisions (RD-ASEP) covering vehicles of categories M₁, N₁, and L₃, with primary objectives to develop amendments from monitoring data, modify current regulations to mandate revised RD-ASEP, update Annex 9, delete Annex 7, and develop consistency between UN R51 and UN R138, chaired by Germany with OICA as Secretary for M/N categories and IMMA for L category, with working documents for motorcycles by January/February 2025, for M₁ and N₁ vehicles by end of 2025 for GRBP discussion in January/February 2026.

Proposal for a reference document concerning a general approach for how to handle measurement uncertainties under UN Regulations within the purview of GRBP.

Proposal to allow using the state-of-the-art test track from the latest standard ISO 10844:2021.

Proposal to allow using the state-of-the-art test track from the latest standard ISO 10844:202

Proposal to complete the additional sound emission provisions’ table of the communication form in the 05 series of amendments to UN R41 to avoid oversight in data collection and entries.

1. Proposal to amend the 04 and 05 series of UN R41 and the 02 series of UN R63 to allow use of the latest state of the art ISO 10844 test track.
2. ISO has updated the ISO 10844 standard to reduce track-to-track variability caused by differing interpretations and implementations of the technical requirements. The tyre/road contribution to the overall sound performance of a motorcycle is lower compared to cars.
3. The improvements from the ISO 10844:2014 to the 2021 version would not result in a need for updating the surface for L-category test tracks: Updating the ISO 10844 reference would have negligible impact on the measurement procedure and measurement results.
4. If however the ISO reference in the L-category noise regulations would be updated without maintaining the current ISO 10844:2014 as an option, IMMA sees a potential risk of tracks needing recertification, creating administrative burden with no practical benefit.
5. If later on, the tracks would need re-surfacing anyway (e.g. due to wear), then these can be built and certified according to ISO10844:2021. Because of the above, IMMA would like to allow certification with the tracks complying to either ISO10844:2014 or ISO10844:2021.
6. This proposal takes the opportunity to introduce proposals for additional corrections in R41/04 and R41/05 as specified below:
   • Supplement 9 to the 04 series of amendments to UN Regulation 41 introduced a new paragraph 12.4, needing to renumber the (former) paragraphs 12.4 to 12.9 (WP.29/2021/4). Due to this renumbering, the reference to paragraph 12.7 in Annex 6 footnote a, and Annex 7 paragraph 2.6 is no longer correct and should be replaced by a reference to paragraph 12.8.
   • With the introduction of the 05 series of amendments the Transitional Provisions were rewritten and footnote a of Annex 6 became obsolete.

Proposal to complete the additional sound emission provisions’ table of the communication form in the 05 series of amendments to UN R41 to avoid oversight in data collection and entries.

German-language report “Motorcycle Noise Study Ausserfern 2019”

Flyer in German and French for a September 2017 technical conference: Lärmarme Strassenbeläge aus Asphalt/Revêtements bitumineux peu bruyants.

Proposal to correct some references, which need to be updated as a consequence of document WP.29/2020/70, adopted at the June 2020 WP.29 session, notably

1. Paragraph 5.4.1 renumbered as paragraph 5.5.1.
2. Paragraphs 5.4. and 5.5. respectively renumbered as paragraphs 5.5. and 5.6.

Proposal to correct some references, which need to be updated as a consequence of document WP.29/2020/70, adopted at the June 2020 WP.29 session, notably

1. Paragraph 5.4.1 renumbered as paragraph 5.5.1.
2. Paragraphs 5.4. and 5.5. respectively renumbered as paragraphs 5.5. and 5.6.

Proposal to correct some references, which need to be updated as a consequence of document WP.29/2020/70, adopted at the June 2020 WP.29 session, notably

1. Paragraph 5.4.1 renumbered as paragraph 5.5.1.
2. Paragraphs 5.4. and 5.5. respectively renumbered as paragraphs 5.5. and 5.6.

Proposal to clarify UN R41 and introduce provisions to improve testing to be more representative of real-world operation by expanding the scope of test and to align the Regulation with ISO 10844:2014, replacing provisions from ISO 10844:1998 (and proposing a clearer image for Figure 1).

Proposal to align the 04 series of amendments with ISO 10844:2014, replacing provisions from ISO 10844:1998 (and proposing a clearer image for Figure 1).

Updated version of document GRBP-71-13-Rev.2 submitted for the September 2020 GRBP session.

Per the transitional provisions of Supplement 3 to the 04 series of amendments, from 20 January 2021, the specifications for the test site reproduced in Annex 4 will be replaced by the provisions of ISO 10844:2014. Therefore, this proposal aims to align the 04 series of amendments with ISO 10844:2014, replacing provisions from ISO 10844:1998 (and proposing a clearer image for Figure 1).

Proposals prepared by the ASEP II informal working group to clarify UN R41 and introduce provisions to improve testing to be more representative of real-world operation by expanding the scope of tests.

The scheduled 1-2 July session has been postponed. A new date will be announced when available.

Article commenting on the German Federal Council decision regarding reduction of motorcycle noise.

Motorrad online article concerning Austrian measures to ban loud motorcycles from certain roads.

Proposal to introduce provisions for stationary noise measurements on a single-sided dual exhaust system, minimize proliferation of approval numbers from models with differences in vehicle exhaust and silencing systems, and correct an omission regarding the compensating resevoir fill time thereby aligning UN R41 with the other noise UN Regulations Nos. 9, 51 and 63.

Text by IWG ASEP for revision of ASEP as a future concept of real driving

Text submitted by chair of IWG ASEP for the status report

The text was prepared by the expert from the International Motorcycle Manufacturers Association (IMMA) to amend Supplement 6 to 04 series of amendments, aiming to minimize proliferation of approval numbers

Presentation by the expert of IMMA supporting the proposed amendment to ASEP (GRBP-71-17)

The text was prepared by the expert from the International Motorcycle Manufacturers Association (IMMA) to amend the ASEP requirements

The text prepared by the expert from the International Motorcycle Manufacturers Association (IMMA) to amend UN Regulation No. 41-04 (up to Supplement 7), in order to clarify the implications of footnote one on the requirements specified in Annex 4.

Proposal for amendment by IMMA to address the issue of stationary noise measurements on a single sided dual exhaust system.

Proposal to minimize proliferation of approval numbers from models with differences in vehicle exhaust and silencing systems.