[Noisebridge-discuss] The rats are getting ballsy

[Joel Jaeggli]

Apart from the fact that the reasonably rigorous research on the subject
says that they don't work, there's also the inverse square law to consider.

and of course:

http://www.ftc.gov/opa/2001/05/fyi0128.shtm

Tomm wrote:
> I ordered a package of 4 of the Pestchaser ultrasound rodent repellers
> Rubin mentioned.  My day job is in ultrasound, and I want to take one of
> the apart and see what they're doing.  They're almost certainly using
> PZT piezo crystals to achieve the stated 5-7 year battery life, but I
> want to see what drive circuitry they're using.  I'll install the other
> 3 at noisebridge - probably won't hurt. 
> 
> No one will be able to hear these devices at a distance of >50cm or so. 
> The Pestchaser uses 32khz to 62khz ultrasound, which is far outside
> human hearing range.  Most people can hear up to about 20khz, some up to
> about 23khz (myself included), but no one has ears that can directly
> hear a 32khz sound.  
> 
> The 40khz air ultrasound devices I work with are barely audible at about
> 10cm, but mostly because it's so damn loud (115dB) that the 20khz,
> 10khz, and 5khz harmonics created in the ear are loud enough to be
> perceived. It's a pulsed device, and sounds like a "tic" when running,
> not like high-frequency tone.  So, while one might hear a little bit of
> tic'ing if you put the Pestchaser next to your ear, there's no way
> you'll near it if it's near the floor and you aren't lying down next to
> it.  For comparison, a plane taking off from 10m away is 115dB.
> 
> Even dogs can barely hear 40khz.  See this graph:
> http://www.lsu.edu/deafness/HearingRange.html  , where their perception
> of loudness drop about 60dB between a 30khz signal and a 40khz signal. 
> Humans have a comparable drop between 15khz and 20khz.  40khz is right
> out.  Mice, on the other hand, hear just fine at 40khz, with the
> distress call of a young mouse at about 40khz (after all, mice don't
> want their distress calls to attract the cat, let alone a human!).
> 
> I've been dubious of the ultrasound devices for pest control.  As anyone
> in the Cyborg group will tell you, any consistent stimulus will
> eventually be integrated into your brain, and rodents would just because
> used to the sound.  The Pestchaser manufacturer claims that it puts out
> a non-periodic sound and that rodents can't become habituated to it,
> which I'm skeptical of but I suppose it might work just by annoying
> them.  After all, rats live in subway tunnels right next to trains
> rushing by at 130dB+.  The pestchaser says that it sends out a special
> 46.5khz sound that mimics the sound of a dominant mouse, which sound
> nifty but likely doesn't help with rats.
> 
> Speaking of which, I'm pretty sure that ultrasound repellers will work
> far better with mice than with rats. Mice are at the bottom of the food
> chain, and anything that moves likely wants to eat them.  A lab
> researcher friend (that is, um, very much not a vegan) says that it's
> impossible to get mice to relax  Rats, on the other hand, are smart
> badasses that chill out all the time, as any rat pet owner will tell
> you.  Pestchaser claims to have been effective with rats, but I'd guess
> their "15 of 17 sites cleared" claim were mostly mice sites, with
> perhaps a few rats deciding that there are easier targets without all
> this racket.
> 
> That all said, my experience backs up what I've been told by pest
> control professionals: plugging holes works the best.  Rats can fit
> through an opening the size of a quarter, and mice the size of a dime. 
> Plug them up, and they're less likely to enter not only because of
> chance (hey look, an open hole!) but because there are a lack of exits
> (oh shit, nowhere to escape to!)  Spackle won't work because they'll
> just eat through it.  High density urethane spray foam, available at
> most any hardware store, is your friend.  I inherited a minor rat
> infestation at a house in Berkeley, and two cans of spray foam later, I
> never saw rat traces again.
> 
>     Tom
> 
> On 2/24/2010 1:08 PM, Rubin Abdi wrote:
>> ====Ultrasonic====
>> * Get ultrasonic emitters. 
>> [http://www.amazon.com/Victor%C2%AE-PestChaser%C2%AE-Ultrasonic-Rodent-Repellent/dp/B0015WM4QA/ref=sr_1_4?ie=UTF8&s=home-garden&qid=1267045186&sr=8-4]
>> * Set them up outside of the space.
>> ** At the end of the ledge holding the lights in the main stairs.
>> ** In the not-a-fire-escape stairwell.
>> ** At the bottom of the stairs under the DJ booth.
>> * See if any humans can hear them.
>>
>> ====Peppermint====
>> * Get some peppermint.
>> * Spread it around the space without stinking up the space.
>>
>>   
> 
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