ECMA-418-2 roughness, a challenging implementation

Over the past decade, psychoacoustics has grown significantly and sound quality metrics have become an easy way to include the human factor in NVH analysis. Most of these metrics have been defined by standards (ISO, DIN, ANSI or ECMA), which should promote their use in industrial applications. MOSQITO is an open-source project providing implementations of sound quality metrics in Python(e.g. loudness ISO 532-1, sharpness DIN 45692, SII ANSI S3.5) along with complete documentations and validation procedures. In 2020, the European Computer Manufacturers Association released the ECMA-418-2 standard, revised in 2022, describing new loudness, roughness and tonality implementations based on a common hearing model. During the implementation of the roughness metric in MOSQITO, it appeared that some implementation instructions are subject to interpretation, and some information was missing in the standard to allow for a valid computation of this metric. Moreover, the standard does not define some validation cases, which can limit the spread of its metrics. This paper highlights these difficulties for each section of the calculation process, and proposes new steps that would aid the user's understanding and implementation of the standard.