Corrections to documents submitted by TF-AVRS and approved by GRBP amend terminology in UN R51.03 to harmonize bidirectional spelling, correct vehicle category references in UN R51.03 and UN R165 to reference category X only rather than non-existent category M1Y or category M, clarify in UN R64 that logical signals shall be transmitted to the ADS when an ADS feature is active, introduce references to specific ADS provisions in Annexes 5 and 7 of UN R138.02 and UN R165, add grammatical corrections to UN R141, and align UN R165 terminology with ADS regulation language.

The session will cover database analysis including review of documents and discussion points from pilots view, AVAS term dL Dynamic factor x, review of decisions and work for the next meeting.

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.

Japan comments on the draft 04 series of amendments to UN R51 (Noise of M₁–M₃ and N₁–N₃ Categories of Vehicles). Japan highlights several editorial and technical issues. Regarding para. 2.24.1, Japan suggests the table of symbols for Annex 3 should state symbols are “used for the first time” consistent with ISO standards. For para. 3.1.2.1.4.3, Japan requests deletion of “but no more than 2.0 m/s²” as unnecessary for RD-ASEP applied to electric vehicles. Japan notes para. 6.2.3.4 should reference appropriate appendices for the RD-ASEP statement of compliance requirement. Paragraphs 11.1.4 and 11.1.5 are identical and one should be deleted. Japan flags para. 3.2.3.4.2 requires tyre conditioning on outdoor test tracks for indoor testing. For Annex 6, para. 3 should clarify that compliance assessment references para. 5 of Annex 7 for expected sound pressure level limits applicable to conformity of production testing.

The IWG RD-ASEP informal group is developing a mandatory procedure for UN R51 after the monitoring phase. The Analysis Task Force determined vehicle databases and expectation models are suitable for RD-ASEP development. The Editing Task Force created a consolidated R51.04 draft submitted to GRBP-84. The revised R51.04 RD-ASEP includes manipulation and defeat device provisions, mandatory random testing for approval, revised control range, any acceleration position testing, vehicle speed range 0-100 km/hr, and vehicle performance criteria. A revised companion document GRB-68-03 is necessary.

The Task Force Data Analysis held its 12th session on 28 April 2026. Database version 3 requires further corrections to reflect IWG decisions on v_test, parallel and serial hybrids, and German input; version 4 will be delivered. The group reviewed German input on database issues and decided to establish an Excel list documenting observations, background information, and proposed solutions. Additional data are needed on gear shifting during pass-by measurement, ICE ON/OFF shifting, low speed measurements below 30 km/h, high performance vehicles with acceleration greater than 5 m/s² at high speeds, and EV data.

Results of the review of proposals for UN Regulations R28, R51, R64, R138, R141, R142, and R165 regarding autonomous vehicle readiness. Key findings include: inconsistent Mass in Running Order definitions between R51 and R138 versus RE3; unclear special testing provisions in R64, R138, and R165; need for clarification on ADS optical and logical signal transition in R64; redundant full definitions from RE3 in multiple proposals should reference RE3 via footnote instead; inconsistent ADS activity terminology across R64, R141, and R165 should be standardized; incorrect Category Y references in R51 Table 2; and definition and spelling errors in R51, R138, R141, and R165.

The RD-ASEP Informal Working Group met April 14-16, 2026 in Berlin. The Analysis Task Force concluded data cleaning and will use data to answer questions and update the parameter table. The original aim of RD-ASEP was to address vehicles with louder partial throttle than full throttle results. The Editing Task Force reviewed draft R51.04 and was directed to provide an updated draft for the June meeting, replacing the old Annex 7 with the current Annex 9. The Chair requested the Editing Task Force prepare a summary report to GRBP for September evaluating the monitoring database, Expectation Model, and draft R51.04.

The 21st session of the Task Force on Vehicles Sound will be held on Tuesday 9th June 2026 from 13:00 to 17:00 (CEST) as a hybrid meeting in Gothenburg, Sweden. The agenda includes adoption of the agenda and report of the 20th session, exchange of information on national and international requirements with presentations on anoise figures in vehicle certificates of conformity versus perceived noise" and on “transportation noise and cardiovascular health”, cross-matrix follow-up discussion, discussion on updating the guidelines of the task force as approved in GRBP-74-03 Rev.1, any other business, and determination of next meeting and provisional agenda.

The Task Force Data Analysis (Sub Group to IWG RD-ASEP) will hold its 12th meeting on Tuesday, 28th April 2026. The agenda includes a review of the meeting schedule with targeted meetings on 19th May, 3rd June, and 9th June, review of database version 3 status and input from Germany on database issues, review of analysis performed, and review of decisions and work for the next meeting.

Proposal to add, modify, and amend Annex 3, Annex 4, Annex 5, Annex 6, Annex 7, Annex 8, Annex 9, and Annex 10, insert Annex 9 (Measurement method to evaluate compliance with the Real Driving Additional Sound Emission Provisions (RD-ASEP)), and add provisions concerning sound emissions, test methods, measurement instruments, vehicle specifications, conformity of production, exhaust systems, compressed air noise, indoor testing, and specific provisions for vehicles equipped with an Automated Driving System (ADS).

Proposal to add, modify, and amend Annex 3, Annex 4, Annex 5, Annex 6, Annex 7, Annex 8, Annex 9, and Annex 10, insert Annex 9 (Measurement method to evaluate compliance with the Real Driving Additional Sound Emission Provisions (RD-ASEP)), and add provisions concerning sound emissions, test methods, measurement instruments, vehicle specifications, conformity of production, exhaust systems, compressed air noise, indoor testing, and specific provisions for vehicles equipped with an Automated Driving System (ADS).

Proposal to introduce new definitions for Automated Driving System (ADS), Dynamic Driving Task, bidirectional vehicles, Enhanced Exterior Sound (EES), and Vehicle Master Control Switch; amend specifications for test mass, sound levels, and measurement procedures for vehicles of categories M₁–M₃, N₁–N₃, and vehicles equipped with an ADS; add provisions for vehicles electrically propelled without internal combustion engines; establish ASEP control ranges and calculation methods; and insert Annex 10 with specific provisions for testing vehicles equipped with an ADS.

The Data Analysis task force met with limited participation from Japan, Netherlands, and the pilot. The group reviewed corrections made to vehicle load issues and reference speeds. They determined that corrections to PMR and L_urban calculations would be too time-consuming without adding substantial benefit and are not currently used by the model. A proposal for generic reference acceleration determination requires further assessment, as initial analysis indicates the formula overestimates acceleration potential. The data review process should be closed, so the official work with the database can start.

The Task Force Data Analysis has almost completed data revision for RD-ASEP specifications, identifying inconsistencies and proposing corrections. Key considerations include: updating database limits to UN R51.03 phase 3, clarifying vehicle reference speed interpretation, correcting reported loads exceeding 100%, selecting correct parameter tables, defining run interdependency, strengthening tyre rolling sound specifications, resolving minimum dynamic calculation inconsistencies, improving gear shifting detection, reconsidering sound level maximum basis, increasing performance validity threshold, accepting runs outside control range with manufacturer agreement, and reviewing AVAS term application for hybrid vehicles.

The Task Force Data Analysis agenda covers welcome and agenda adoption; review of meeting schedule with sessions scheduled through June 2026; discussion of actions and considerations for the IWG and Editing group; review of vehicle review list Version 19; database status and release timing; decisions and work for subsequent meetings; and closing remarks.

The Task Force Data Analysis completed data revision for RD-ASEP specifications, identifying errors and inconsistencies. The document lists considerations for database improvements, including updating limits to UN R51.03 phase 3, clarifying vehicle reference speed definitions, correcting reported loads exceeding 100%, selecting correct parameter tables, and addressing gear shifting detection. Additional recommendations involve determining acceptable factor x ranges, resolving minimum dynamic calculation inconsistencies, increasing va_MAX validity thresholds, and reconsidering AVAS term applicability for hybrid vehicles.

Consolidation in Supplement 11 includes: clarification of Verification/Adjustment and editorial corrections with transitional provisions (GRBP/2025/20 with GRBP-82-07); correction of Tyre Road Sound Measurement for Indoor-Testing (GRBP-82-22); introduction of ASEP in Annex 7 for BEVs and HEVs (GRBP/2026/4 with GRBP-83-xx); update of ISO standards in Annex 3 and Annex 8 (GRBP/2026/5 with GRBP-83-xx); and reference for Power Definition regarding new UN R177 (GRBP/2026/13). The consolidated version of Supplement 11 is to be submitted to the 199th WP.29 in June.

ISO 362-3:2022 specifies an engineering method for measuring pass-by sound level of a vehicle under controlled indoor conditions using a semi-anechoic chamber. The 2022 edition incorporates technological advancements and improves usability and accuracy of the measurement procedure. Improvements include additional microphones, tire temperature correction harmonized with UN R51.03, clarified indoor room qualification criteria, and normalized torque influence equation. Transitional provisions propose accepting ISO 362-3:2022 for all approvals from entry into force of Supplement 11, while ISO 362-3:2016 remains accepted for five years thereafter.

Proposal to amend Annex 3 of UN Regulation No. 51-02, paragraph 3.1.2.3.2.3, third paragraph, to require gear shifts beginning with (x/n) continue in all gears at which rated engine speed is reached immediately before the rear of the vehicle passes line BB’, rather than being completed in gear X only, based on WP.29-196-08 and WP.29-197-11 findings of non-compliance with permissible sound level requirements for category N₃G vehicles during state control testing.