Jun 16, 2012

The Depressing Horn Test

Back in 2007, Pat Hahn and I tested the "effectiveness" of motorcycle horns. I, finally, got the test posted to my own website after the MN state website decided to purge all of the Hi-Viz history. The results were somewhere between startling and depressing.

Click on the picture of the webpage and a link will take you to the test results.


  1. That is pretty depressing. And sitting on the desk in front of me is one of the 139db Stebel horns waiting for me to install. (It's been sitting there for a while.)

    I guess the horns are just to signal other riders...

  2. There are some good horns out there, but the biggest problem on motorcycles is that there is no place to put them (unless you're riding a hippo bike). Installing new wiring with a relay, relocation and mounting brackets are beyond most people as well.
    The thing about horns is basic physics - bigger is better; you don't have any trouble hearing the air driven trumpets on a truck. Hella makes a disc horn set called the Supertone that is very highly regarded, but they're 6 inches in diameter each, which doesn't sound like much until you try to find a way to mount them properly on a bike.

  3. I guess I wasn't surprised at the ineffectiveness of motorcycle horns, but I was surprised that horns in general are so useless in penetrating a "modern" car (the Escort barely qualifies). I have done some acoustical engineering in the area of isolation and car designers are treating cars like the interior of a studio. More people use their air conditioning to keep the noise down (for cell phone conversations). All combines to make a car a rolling, well-designed house.

  4. Very interesting, but I find the most common situation where I use a horn is to alert a driver at a stop sign on a cross street that I am coming. Maybe coming from the side is more effective? At least I notice that a fair number of times the wimpy tone from my stock horn catches their attention, though I don't count on it. I suspect the most important things in this situation are the headlights, some lateral motion, and hi-vis gear.

  5. Your bias is showing. If horns didn't work the bike companies wouldn't install them or the feds would make them put louder horns on bikes. Loud pipes work too I know.

  6. To anon, horns are installed because they're required equipment. There are no federal standards for horns like there are for lighting and other equipment.
    Horns for bikes are a legal catch-22; if the manufacturer comes out and says "we're putting louder horns on for safety" it opens them up to litigation for the substandard horns that had been used in the past.
    And if you really believe in loud pipes as a signaling device you should have them mounted facing forward for max effectiveness.

  7. Inside a cage, the "signal" from loud pipes is primarily LF (low frequency) which is perceived as omnidirectional; no directional cues provided. Loud pipes are a signaling device when they are directly beside a car or in front, but visual cues are more powerful and meaningful. Dump the black Village People outfit and go hiviz and you won't have to go deaf.


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