Articles tagged “Noise Criteria”
13 articles covering Noise Criteria in acoustic engineering and building design.
ASHRAE Noise Criteria for HVAC Systems: NC, RC, and Design Limits
Master ASHRAE HVAC noise criteria — NC curves, RC Mark II method, design limits by room type, duct noise calculation, and common specification errors.
Background Noise Curves: NR, NC and RC Compared
Compare NR, NC, and RC background noise rating methods with worked examples showing which curve to specify for HVAC noise control in offices, studios, and hospitals.
BS 8233:2014 Sound Insulation & Noise Reduction — The Definitive Guide
Complete guide to BS 8233:2014 sound insulation and noise reduction for buildings — indoor ambient noise levels, criteria tables, and field compliance.
What is HVAC Noise? Controlling Mechanical System Sound in Buildings
HVAC noise is unwanted sound from heating, ventilation, and air conditioning systems. Learn noise generation mechanisms, NC/NR criteria, duct attenuation, and practical control strategies.
What is an NC Rating?
NC (Noise Criteria) is an octave-band rating system for background noise in buildings. Learn how NC curves work, how to read them, target values by room type, and how NC relates to NR and RC.
What is Noise? (Wanted vs Unwanted Sound)
Noise is unwanted sound that interferes with communication, concentration, or comfort. Learn how noise is measured, classified, and controlled in building acoustic design.
Free BS 8233 Quick Reference Guide — UK Indoor Noise Level Criteria (PDF)
BS 8233:2014 indoor noise level targets for dwellings and other buildings. Table 4, Table 5, ventilation noise allowance, WHO guideline values, and relationship to Approved Document E.
HVAC Noise Control — The Ductwork Mistake Ruining Your NC 30 Spec | AcousPlan
HVAC duct velocity above 5 m/s generates noise proportional to V⁵. NC curve calculation chain with ASHRAE method. 5 noise sources, 1 worked example.
NC vs RC vs NCY — Which Noise Criterion? Most Engineers Pick Wrong | AcousPlan
NC misses rumble below 63 Hz. RC Mark II identifies spectral quality. NCY adds 5 dB penalty. Full comparison with decision matrix and worked example.
What Is Noise Criteria (NC)? — Background Noise Rating for Buildings
NC curves rate background noise across octave bands to reflect how human hearing perceives HVAC and mechanical noise. Learn what NC numbers mean, how they are measured, and what targets apply to your building type.
Office Background Noise Limits: BS 8233 vs WELL v2 vs ASHRAE vs AS 2107 vs DIN 4109
Office background noise criteria compared across five international standards: BS 8233, WELL v2 Feature 74, ASHRAE 189.1, AS 2107, and DIN 4109. Real limits, measurement methods, and compliance explained.
NC Curves Explained: Understanding NC-25, NC-35, NC-45 Background Noise Ratings
A comprehensive guide to Noise Criteria (NC) curves: how they work, how to determine an NC rating, target values for every room type, and the differences between NC, NR, and RC rating methods. Includes ASHRAE recommended levels and step-by-step calculation examples.
Noise Criteria Explained: NR, NC, and RC Curves — Which One Does Your Project Need?
NR (Noise Rating), NC (Noise Criteria), and RC (Room Criteria) all rate background noise levels in buildings — but they use different curves, different frequency ranges, and are required by different standards. Here is how each system works, when to use which, and the specific values your HVAC engineer needs to hit.