There is a noise limit at the Ring of 95db(A), and regular tests are carried out both at the barriers and by trackside measurements.

There still appears to be an element of pot-luck in who gets tested and how strictly the limit is enforced, but certainly things are stricter than they have been in the past, and you are strongly recommended to get to within the 95db(A) limit if you can - otherwise your visit could be a very short one.

There are three ways you can get tested.

First, if your car or bike seems noisy to the marshalls at the barriers, you will be pulled over for a static test.

Second, if your vehicle triggers one of the trackside noise-meters, the office will be alerted and you'll be tested at the end of the lap.

Third, some random testing is done in the car-park.

Note also that German police have powers to confiscate noisy cans, which can spoil your day, especially if you've ridden there ...

If you are in any doubt about your own car or bike, you can buy a noise-meter from somewhere like RS or Maplin for £30 or £40.

Testing is done with the meter held at a 45-degree angle approximately 1 metre from the exhaust, with the engine revs at 2/3rds of redline. You can see in both the photos above and below that one marshall checks the revs while another reads the noise-level: