Independent Assurance Report

on selected KPIs in the ESG Report 2022/23
to the Board of Directors of Sonova Holding AG, Stäfa.

Zurich, 10th of May 2023

We have been engaged to perform a limited assurance engagement (the engagement) on selected KPIs disclosed in Sonova Holding AGʼs and its consolidated subsidiariesʼ (the Group) ESG Report 2022/23 (the report) for the reporting period from 1 April 2022 to 31 March 2023. The KPIs in scope of the limited assurance (the KPIs) are marked with a “✔ Data externally assured (limited assurance)” in the ESG Report 2022/23.

Other than as described in the preceding paragraph, which sets out the scope of our engagement, we did not perform assurance procedures on the remaining information included in the report, and accordingly, we do not express a conclusion on this information.

Applicable criteria

The Group defined as applicable criteria (applicable criteria):

  • Global Reporting Initiative (GRI Standards). A summary of the standards is presented on the GRI homepage.
  • The Groupʼs own methodology available in the relevant sections of the ESG Report 2022/23.

We believe that these criteria are a suitable basis for our limited assurance engagement.

Responsibility of the Board of Directors

The Board of Directors is responsible for the selection of the applicable criteria and for the preparation and presentation, in all material respects, of the disclosed KPIs in accordance with the applicable criteria. This responsibility includes the design, implementation, and maintenance of internal control relevant to the preparation of the KPIs that are free from material misstatement, whether due to fraud or error.

Independence and quality control

Our firm applies the International Standard on Quality Control 1, Quality Control for Firms that Perform Audits and Reviews of Financial Statements, and Other Assurance and Related Services Engagements, and accordingly maintains a comprehensive system of quality control including documented policies and procedures regarding compliance with ethical requirements, professional standards and applicable legal and regulatory requirements.

Our responsibility

Our responsibility is to express a conclusion on the above mentioned KPIs based on the evidence we have obtained. We conducted our limited assurance engagement in accordance with the International Standard on Assurance Engagements (ISAE) 3000 Assurance Engagements Other than Audits or Reviews of Historical Financial Information and the International Standard on Assurance Engagements (ISAE) 3410 Assurance Engagements on Greenhouse gas Statements. These standards require that we plan and perform this engagement to obtain limited assurance about whether the KPIs in the report are free from material misstatement, whether due to fraud or error.

Summary of work performed

Based on risk and materiality considerations we have undertaken procedures to obtain sufficient evidence. The procedures selected depend on the practitionerʼs judgment. This includes the assessment of the risks of material misstatements in the above mentioned KPIs. The procedures performed in a limited assurance engagement vary in nature and timing from, and are less in scope than, for a reasonable assurance engagement. Consequently, the level of assurance obtained in a limited assurance engagement is substantially lower than the assurance that would have been obtained had we performed a reasonable assurance engagement.

Although we considered the effectiveness of managementʼs internal control when determining the nature and extent of our procedures, our assurance engagement was not designed to provide assurance on internal control. Our procedures did not include testing control or performing procedures relating to checking aggregation or calculation of data within IT systems.

The Greenhouse Gas (GHG) quantification process is subject to scientific uncertainty, which arises because of incomplete scientific knowledge about the measurement of GHGs. Additionally, GHG procedures are subject to estimation (or measurement) uncertainty resulting from the measurement and calculation processes used to quantify emissions within the bounds of existing scientific knowledge.

Our limited assurance procedures included, amongst others, the following work:

  • Assessment of the suitability of the underlying criteria and their consistent application
  • Interviews with relevant personnel to understand the business and reporting process, including the sustainability strategy, principles and management
  • Interviews with the Groupʼs key personnel to understand the sustainability reporting system during the reporting period, including the process for collecting, collating and reporting the KPIs
  • Checking that the calculation criteria have been correctly applied in accordance with the methodologies outlined in the applicable criteria
  • Analytical review procedures to support the reasonableness of the data
  • Identifying and testing assumptions supporting calculations
  • Testing, on a sample basis, underlying source information to check the accuracy of the data

Other Matter

The period from 1 April 2020 to 31 March 2021 and the period from 1 April 2021 to 31 March 2022 of the Group were subject to limited assurance engagements by another practitioner who expressed unmodified conclusions.


Based on the procedures performed and the evidence obtained, nothing has come to our attention that causes us to believe that the KPIs for the reporting period from 1 April 2022 to 31 March 2023 have not been prepared, in all material respects, in accordance with the applicable criteria.

Ernst & Young Ltd

Roger Müller                                                                 Claude-Aline Dubi
Partner                                                                          Manager