The robust assessment of noise annoyance is of key importance given that it is the most prevalent community response in populations exposed to environmental noise. In 1993, the International Commission on Biological Effects of Noise Community Response to Noise team began formalizing a standardized methodology for assessing noise annoyance, which resulted in reporting guidelines and recommendations later published as a Technical Specification (TS) by the International Standards Organization in 2003 (ISO/TS 15666: 2003). This TS, intended to inform the international community on the quantification of the exposure-response relationship between noise exposure and annoyance, has been in circulation for nearly two decades and has been updated in 2021 (ISO/TS 15666: 2021) by an international working group (ISO TC43/SC1/WG62). This paper reviews use of the 2003 TS, identifies common adaptations in use, and summarizes the revisions. Methodological issues arising from the use of the 5-point verbal and the 11-point numeric scale questions and the scoring of “highly annoyed” are discussed. The revisions are designed to encourage further standardization in noise annoyance research. This paper highlights research needs that if addressed would strengthen the methodology underlying the assessment of noise annoyance, including multidimensional assessments of annoyance.