IS 9736:1981 is the Indian Standard (BIS) for glossary of terms applicable to acoustics in buildings. This standard serves as a glossary, defining technical terms used in the field of building acoustics. It covers fundamental concepts related to sound, its transmission, absorption, reverberation, and noise control, establishing a common vocabulary for professionals.
Glossary of terms applicable to acoustics in buildings
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Reference Sound Pressure (air) | 2 x 10⁻⁵ N/m² | 20 μPa (equivalent to 2 x 10⁻⁵ Pa) | ISO 80000-8:2020 |
| Reference Sound Intensity | 10⁻¹² W/m² | 10⁻¹² W/m² | ISO 80000-8:2020 |
| Noise Reduction Coefficient (NRC) definition | Arithmetic average of sound absorption coefficients at 250, 500, 1000, and 2000 Hz, rounded to the nearest 0.05. | Arithmetic average of sound absorption coefficients at 250, 500, 1000, and 2000 Hz, rounded to the nearest 0.05. | ASTM C634 / C423 |
| Constant in Sabine's Formula (Metric) | 0.16 (in T = 0.16 V/A) | 0.161 (in T = 0.161 V/A). The value 0.161 is more precise. | ASTM C423 |
| Term for Airborne Sound Insulation of a Partition | Sound Reduction Index (R) | Sound Reduction Index (R) in ISO/EN standards; Transmission Loss (TL) in ASTM standards. | ASTM C634 / ISO 10140 |
| Unit for Total Sound Absorption in a room | Sabin (Metric Sabin) | m² or Sabin. The unit name is consistent, though modern standards emphasize the use of m² (equivalent absorption area). | ASTM C634 |
| Frequency Weighting Curves | Defines A, B, and C weighting networks. | Defines A, C, and Z (Zero) weighting. B-weighting is now obsolete and no longer included in current standards. | IEC 61672-1 |