IEC TR 63558:2025 delineates the variables pertinent to classifying real-world environments based on acoustic and linguistic cues. This compendium of factors is instrumental in characterizing the intricacies of usage scenarios, ranging from level 1 to level 4, and can prove beneficial in the establishment of testing environments. The document is applicable to the assessment of automatic speech recognition technology, a technology that is extensively employed in smart devices, including smart speakers.