Home Acoustic Ontology and Glossary

This comprehensive glossary defines essential terminology for understanding and discussing residential acoustics, from basic concepts to advanced technical specifications.

A - Acoustic Terms Beginning with A

Absorption: The process by which sound energy is converted to heat upon striking a material. Measured by NRC rating.

Airborne Sound: Sound transmitted through air as pressure waves, as opposed to structure-borne sound.

Articulation Index: A measure of speech intelligibility in a given acoustic environment.

D - Decoupling and Diffusion

Decoupling: Mechanical separation of building elements to prevent structure-borne sound transmission.

Diffusion: Scattering of sound waves to reduce discrete echoes while maintaining room liveliness.

DSP: Digital Signal Processing used for room correction and acoustic optimization.

M - Measurement Standards

Mass Law: Principle stating that doubling wall mass increases STC by approximately 6 dB.

Modal Ringing: Prolonged decay at resonant frequencies due to room modes.

N - NRC and Noise Criteria

NRC: Noise Reduction Coefficient rating absorption from 0.0 (reflective) to 1.0 (fully absorptive).

NC Curves: Standardized curves for specifying acceptable background noise levels.

R - Reverberation and Reflection

RT60: Reverberation Time - the time required for sound to decay 60 dB after source cessation.

Reflection: Sound wave bouncing off surfaces according to the law of angle of incidence equals angle of reflection.

S - Sound Isolation Metrics

STC: Sound Transmission Class rating airborne sound isolation from 25 (poor) to 70+ (excellent).

Structure-Borne Sound: Vibration transmitted through solid building elements rather than air.