Jag vill börja med att säga följande: Ljudmätningar görs av oss för sportens bästa. Inte för att jaga ljudsyndare.
Det som i dag ligger i focus är ljudet. För 10 år sedan var det utsläppen från 2taktare. Vi får acceptera att det i fortsättningen kommer att bli mycket hårdare vad det gäller ljudmätningar.
Enligt SVEMO så får var klubb sätta vilka ljudnivåer de vill. Dock ska man ej överstiga utsatta värden. SVEMO har nu kommit på att det är väldigt svårt att göra en korrekt ljudmätning, utrustningen är väldigt dyr och ska kalibreras med jämna mellanrum. Därav har man kommit fram till en enklare form som kallas 2 meters mätning (klicka på läs mer nedan för mer info om mätmetoden).
Det vi som klubb är ute efter, är dessa eftermarknadsljuddämpare, som låter som ett reaplan. Jag stod nere vid segelsällskapet i tisdags och det var en hoj som stack ut markant. De övriga maskinerna hördes men var inte i närheten av denna maskin. Boende i området kanske inte tycker om oss men har fått acceptera att vi finns där. Men vi behöver inte sticka ut mer än nödvändigt. Vi i styrelsen kommer att följa utvecklingen noggrant och har kontakt med SVEMO som tar fram direktiven för hur vi ska bära oss åt.
Ljudmätning kommer att utföras under maj månad för att försöka få fram ett underlag som vi kan hålla oss till. Om du vet att din hoj dånar betydligt mer än andra hojar så ber vi dig göra något åt den innan körning.
Ordf.
Lars A
2010 SOUND TEST: NEW SOUND TEST TO TEST AT MAXIMUM RPM
According to the FIM:
The FIM Steering Committee for the sound level reduction in Motocross was created in February 2008, with the support of the manufacturers and Youthstream, to define a new method by which to control the sound level of competition motorcycles.
The primary aim of this search was to find a method which accurately links the amount of noise emitted by a static motorcycle during a sound test with the amount that can be heard in the ‘real world’ during track activity.
After testing 40 Motocross and Enduro machines, the Sound Reduction Committee found that the existing method of sound measurement was highly inconsistent; a bike which was ‘quiet’ during the static test could turn out to be ‘noisy’ when on track and vice versa.
The committee found that this could lead to ‘unfair assessments’ – where a machine might be above the sound limit during the static test but below the sound limit on track, or below the sound limit during the static test but above it on track.
A new sound measurement method was therefore sought which would accurately link static test noise and ‘real world’ track noise.
The new system, provisionally known as the ”two meters Max” method (a name which will be modified in 2009) uses the same sound control methods and instruments as those at present.
However, it claims to reduce ‘unfair assessments’ between static test results and track sound to just 5 percent (down from 40 percent).
The system works by placing the microphone two meters behind the contact patch of the motorcycle’s rear wheel and 45 degrees from the centerline of the motorcycle. The microphone sits 1.35 meter from the ground and points towards the exhaust. The microphone unit is tilted at an angle of 45 degrees (up or down).
The test takes place once the engine and exhaust have been warmed up and using the same engine mapping as when on track. With the gearbox in neutral, the engine rpm is quickly raised from idle to maximum rpm by a sudden opening of the throttle (within one second), then returns to idle speed after a sudden release of the throttle.
The new Two Meter Max method will be introduced systematically to the new method as from the 2010 season. Further work to refine the new method will be carried out during 2009. The aim is then to systematically introduce the new method from the 2010 season.
WHY THE PRESENT FIM SOUND MEASURING METHOD IS WRONG.
1. The need for a new sound control method
The on-going effort to reduce sound levels produced by motorcycles when training or competing on our circuits, is based on a gradual reduction of the sound limits at the technical control. However, the main reason is to reduce the sound in the surrounding area. Hence, it is essential to find a good correlation between the sound measured at the initial control and the sound produced on the track – and thus in the vicinity.
This close relation is not observed using the current FIM control method. Therefore, a new sound control method which reflects the real sound (ambient) from the track is a very important part of the fight for less sound.
2. What are the problems with the current FIM method?
There is an absence of a close relation between the sound levels measured with the current FIM control and the real sound levels experienced at the track. On 40 motocross and enduro motorcycles measure, each motorcycle’s sound level was measured at the track and with the current FIM control. When motorcycles which are found ‘noisy’ at the FIM control are exchanged by motorcycles which are less noisy, the sound at the track should ideally go down correspondingly. But this doesn’t happen. Thus the current sound test method is a control method which provides inconsistent results. As a tool, this is therefore unacceptable.
3. Requirements for a new method
Apart from being easy to perform and to understand, an essential requirement for a new control method to be applied is that a certain change of the sound at the control should correspond to an equal change of the sound at the track.
4. Improved quality of the sound control
A measure of the quality of a control method could be the number of ”unfair” measurements. In this context, an unfair assessment is excluding a motorcycle with acceptable sound at the track (unfair to the driver) or not excluding a motorcycle with unacceptable sound at the track (unfair to people in the surrounding area).
5. Conclusion
Given the reasons stated above, the FIM created a ”Steering Committee for sound reduction” at the beginning of 2008, with the participation of all manufacturers and some international experts in the field of acoustics. Many sound level measurements were performed during the 2008 season in FIM World championship Motocross and Enduro events in order to find a better method, easy to be applied and more representative of the sound levels perceived by the spectators and the people
6. The new method
The new method approved by the FIM is the Two Meter Max method. Two meters for the distance that the sound meter is from the exhausts and ”Max” because the rpm will be held at maximum rpm for one second.