1.1 This classification covers methods of calculating single-number acoustical ratings for laboratory and field measurements of sound attenuation obtained in one-third octave bands.

1.2 The name given to the single-number rating is assigned by the test method that invokes this classification.

1.3 Test methods that invoke this classification include:

1.3.1 Test Method E90—The single-number rating is called sound transmission class (STC).

1.3.2 Test Method E336—Single number ratings are noise isolation class (NIC), normalized noise isolation class (NNIC), and apparent sound transmission class (ASTC).

1.3.3 Test Method E596—The single-number rating is called noise isolation class (NIC).

1.3.4 Test Method E1414—The single-number rating is called ceiling attenuation class (CAC).

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.