In another galaxy long, long ago, someone wrote:

Quote:

The Bad Boy only reports 118 db



There have been quite a few discussions in these forums about the Stebel and Bad Boy horns, but I don't think the subject of rating methods has been mentioned (sorry if I've missed it). In short, when SPL (sound pressure level) is used to specify output of a transducer in dB, the rating must also include measurement distance from the source. Most transducers, such as vehicle horns and stereo speakers, are rated at a distance of one meter, with somewhat fewer conforming to a two meter specification. In Stebel's case, the 139 dB claim is accomplished at four inches. Such a spec is largely meaningless unless you plan to throw the horn at the next motorist who cuts you off.

Dealers like to hawk the Stebel at 139 dB for obvious reasons, but a more useful number is available from the manufacturer's site. The company claims 115 dB at two meters, and that translates to approximately 118 dB at one meter. (Half the distance = double the SPL = +3 dB.) That's a much more reasonable number, and more in line with what I would expect from a device like this. Not surprisingly, it also coincides with the Bad Boy claim.

So - which horn is louder, Bad Boy or Stebel Nautilus? I don't know, because I haven't been able to determine the distance at which the Bad Boy rating was achieved. I suspect the two models are virtually identical, but until Wolo publishes the data, there's no way to know for sure. It's worth noting that there are also different weighting systems for making SPL measurements, and that can substantially affect the numbers. The bottom line is that all the relevant information is required in order to make a knowledgeable decision. Lacking that, you might as well just order the model that mounts the easiest or looks the best.

One last bit of errata: I've come across a few ads in which manufacturers or dealers claim that doubling the SPL (adding 3 dB) produces a horn that's twice as loud. In fact, an increase or decrease of 3dB corresponds to a change that is barely perceptible to the human ear. Loudness and SPL are not at all the same thing and are not interchangeable when discussing the effectiveness of a horn.

My search on these particular horn ratings came about because I was squeezed out of my lane on the local loop earlier this week. Traffic was roughly 65MPH, and if I hadn't hit the brakes quickly, it would have been a serious accident. The cager seemed not to even notice that I was leaning on the horn. I ordered a Stebel within 30 minutes of arriving home.

Hope this info is helpful to other riders. More info on dB (decibels) can be found here:

http://www.phys.unsw.edu.au/jw/dB.html



Jack

Last edited by Lazyrider; 08/09/2008 3:00 AM.