To read a copy of the noise regulations under which all circuit activity takes place please download the PDFs below.
The Motorsport UK is the regulatory body for all four-wheeled motorsport in the UK. Noise regulations are in section C(b), pages 146-149 of the Blue Book.
The document is available to download by clicking here
Certain historic cars are exempt from these regulations due to their period status. These are defined by FIA (Federation Internationale de l'Automobile) regulations, found in Appendix K, Article 3.
The relevant document is available to download by clicking here
Motorcycle racing is governed by the ACU (Auto-Cycle Union) and its rules and regulations with regards to noise are outlined in section 14.8 on page 22 of its road racing guidelines.
The document is available to download by clicking here