Jag vill b\u00f6rja med att s\u00e4ga f\u00f6ljande: Ljudm\u00e4tningar g\u00f6rs av oss f\u00f6r sportens b\u00e4sta. Inte f\u00f6r att jaga ljudsyndare.<\/p>\n
Det som i dag ligger i focus \u00e4r ljudet. F\u00f6r 10 \u00e5r sedan var det utsl\u00e4ppen fr\u00e5n 2taktare. Vi f\u00e5r acceptera att det i forts\u00e4ttningen kommer att bli mycket h\u00e5rdare vad det g\u00e4ller ljudm\u00e4tningar.<\/p>\n
Enligt SVEMO s\u00e5 f\u00e5r var klubb s\u00e4tta vilka ljudniv\u00e5er de vill. Dock ska man ej \u00f6verstiga utsatta v\u00e4rden. SVEMO har nu kommit p\u00e5 att det \u00e4r v\u00e4ldigt sv\u00e5rt att g\u00f6ra en korrekt ljudm\u00e4tning, utrustningen \u00e4r v\u00e4ldigt dyr och ska kalibreras med j\u00e4mna mellanrum. D\u00e4rav har man kommit fram till en enklare form som kallas 2 meters m\u00e4tning (klicka p\u00e5 l\u00e4s mer nedan f\u00f6r mer info om m\u00e4tmetoden).<\/p>\n
Det vi som klubb \u00e4r ute efter, \u00e4r dessa eftermarknadsljudd\u00e4mpare, som l\u00e5ter som ett reaplan. Jag stod nere vid segels\u00e4llskapet i tisdags och det var en hoj som stack ut markant. De \u00f6vriga maskinerna h\u00f6rdes men var inte i n\u00e4rheten av denna maskin. Boende i omr\u00e5det kanske inte tycker om oss men har f\u00e5tt acceptera att vi finns d\u00e4r. Men vi beh\u00f6ver inte sticka ut mer \u00e4n n\u00f6dv\u00e4ndigt. Vi i styrelsen kommer att f\u00f6lja utvecklingen noggrant och har kontakt med SVEMO som tar fram direktiven f\u00f6r hur vi ska b\u00e4ra oss \u00e5t.<\/p>\n
Ljudm\u00e4tning kommer att utf\u00f6ras under maj m\u00e5nad f\u00f6r att f\u00f6rs\u00f6ka f\u00e5 fram ett underlag som vi kan h\u00e5lla oss till. Om du vet att din hoj d\u00e5nar betydligt mer \u00e4n andra hojar s\u00e5 ber vi dig g\u00f6ra n\u00e5got \u00e5t den innan k\u00f6rning.<\/p>\n
Ordf.<\/p>\n
Lars A<\/p>\n
2010 SOUND TEST: NEW SOUND TEST TO TEST AT MAXIMUM RPM<\/p>\n
According to the FIM:<\/p>\n
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.<\/p>\n
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 \u2018real world’ during track activity.<\/p>\n
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 \u2018quiet’ during the static test could turn out to be \u2018noisy’ when on track and vice versa.<\/p>\n
The committee found that this could lead to \u2018unfair 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.<\/p>\n
A new sound measurement method was therefore sought which would accurately link static test noise and \u2018real world’ track noise.<\/p>\n
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.<\/p>\n
However, it claims to reduce \u2018unfair assessments’ between static test results and track sound to just 5 percent (down from 40 percent).<\/p>\n
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).<\/p>\n
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.<\/p>\n
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.<\/p>\n
WHY THE PRESENT FIM SOUND MEASURING METHOD IS WRONG.<\/p>\n
1. The need for a new sound control method<\/p>\n
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.<\/p>\n
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.<\/p>\n
2. What are the problems with the current FIM method?<\/p>\n
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 \u2018noisy’ 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.<\/p>\n
3. Requirements for a new method<\/p>\n
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.<\/p>\n
4. Improved quality of the sound control<\/p>\n
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).<\/p>\n
5. Conclusion<\/p>\n
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<\/p>\n
6. The new method<\/p>\n
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.<\/p>\n","protected":false},"excerpt":{"rendered":"