Tuesday, November 30, 2010

Noisy Chickens? Quieter than the neighborhood birds in your yard.

When we next meet I will be asking CLUCK supporters to engage in an effort to address EVERY concern raised at last night's City Planning Board meeting. In the meantime, let's look at one single argument that was presented, without opportunity for rebuttal or clarification, by one of the Planning Board members. Noise.

That member, referring to documentation provided by staff, not CLUCK, drew attention to a graphic that indicated the loudest noise made by a chicken could be 70 decibels. This member went on to characterize this decibel level as unacceptable. [For one source supporting the 70 decibel level (in the coop!) see Buffalo Rising.]

Let's put 70 decibels in perspective. The decibel scale is logarithmic, so 70 decibels is ten times more powerful than 60 decibels.

So bear in mind that this would be a maximum of 70 decibels in your neighbor's yard, presumably at the chicken source, so there would be some sound attenuation as a result of distance and any vegetation, etc. We all have an implicit understanding that as one moves further from a sound source, it becomes harder to hear. That's partly why it is so hard to eavesdrop on a normal conversation from a few feet away. Low frequency sounds travel further than higher, which is why we hear the bass line of the party next door before the other elements of the music.

How significant is the dropoff or attenuation? Why not play around with a website that helps calculate such matters? I found one called "Engineering Page". You plug in some numbers at it crunches them. I don't claim to understand terms such as quarter spherical transmission paths, but by trying different numbers one can gain a sense of how distance affects sound. So I tried all the combinations.

I plugged 70 in for the decibels one foot from the source. And put 20 feet in for the distance from the source. Then I tried different transmission paths and both pressure levels and power levels. The answers for a sound of 70 decibels (as measured one foot from the source) that has traveled 20 feet ranged from 43.3 to 49.3 -- so use the highest figure and round to 50 decibels. Because of the logarithmic scale that sound is 100 times less powerful than 70 decibels. As we experience it, another site suggests 50 decibels sounds one fourth as loud as 70 decibels.

For a more coherent discussion of this phenomena, see page 72 of Bird Song: Biological Themes and Variations.

And let's be upfront in recognizing that Sarasotans can own the Moluccan cockatoo, which can produce sounds at 135 decibels. That equals the loudest crowd noise ever recorded at a college football stadium.

For a general introduction to noise, please consult a table produced by CDC/NIOSH, which should be reputable. According to COMMON ENVIRONMENTAL NOISE LEVELS, normal conversation is about 60 decibels. So the loudest your neighbors chicken might be is ten times normal conversation --- if you're right there having a conversation with the chicken. Air conditioners are in the 50-75 decibel range. So some AC units are louder than chickens and they can run a large part of the day, while hens only occasionally get up to that 70 decibel peak. According to the CDC/NIOSH table, the audio portion of a TV is 70 decibels, so if your neighbor had a TV outside that sometimes went on, that is about what you might hear in terms of decibels. Bear in mind that if you are twenty feet away it will be closer to 50 decibels or less.

But chickens don't produce the drone of an air conditioner compressor, or the tempting-to-eavesdrop murmuring of a TV show -- they are sporadic avian commentators and their contribution to your neighborhood acoustic environment will pale in comparison to the birds in your yard.

Carolina Wren, National Geographic Image
These tiny birds can really deliver a song.
Ours says: "Keith Richards, Keith Richards, Keith Richards"
I have a decibel meter on my iPhone. I'm not sure it would stand up in court, but below 100 decibels it is said to be surprisingly accurate. At 6:45 this morning I stood in my front yard in my bathrobe. The background noise varied from 50-51 decibels. (Right now sitting my house with the fan on the decibel rating is 51-53).

A Carolina Wren starting singing. This is a small bird that weighs less than an ounce and is common in suburban neighborhoods. Now the decibels (bird plus background) clocked in repeatedly at 79 decibels, nearly ten times the loudest hen and I wasn't particularly close to the bird. To hear someone else's recording of one, click here (and catch the dog barking in the background). I suspect the reason no one calls in to complain about Carolina Wrens is that it is a beautiful (but loud) call, doesn't last long, and connects us to the natural world.

Your quieter neighbor's hen's conversations will blend in with the Mockingbirds, Doves, Cardinals, Wrens, etc. that I hope still exist in your neighborhood.

My contention is this: If you live in an air-conditioned house, you won't hear your neighbor's hens. If you are in the yard, or on a lanai or porch during the day, chickens will become part of the avian acoustic environment. Unless they are being eaten alive, you will not hear them at night.

I think we all appreciate the watchdog security function that neighbor's dogs can provide. But they can also be loud continuous barkers. One ASPCA study in an animal shelter found that the barking of large, adoptable dogs exceeded 70 decibels over 85% of the time. Of course, that is indoors with the sound reverberating off solid surfaces. But it in the early morning is not uncommon for me to hear dogs barking that I know are 4/5 of a mile away.

And please write to clarify what it is I'm hearing when I wake up at 2:00 a.m. to the sound of cats screaming. Are they mating? Fighting? Both at the same time?

Hens make noises at times during the day. No one claims otherwise. They will cluck, cackle, and make 22 discernible other sounds, most of which will be far less powerful than 70 decibels. But to characterize hen commentary on the other side of the fence as untenable is a clear stretch.

Your neighbor's hens will be less noisy than many, if not most, of the birds you hear in your own yard.

1 comment:

powersmom said...

In a rural setting, we had chickens for thirty years. Except for the rooster, the other farm animals were much louder.
A couple of hens, unless alarmed or attacked would be more compatible in a backyard coop than a dog. Their 'communication' is amongst themselves....and maybe comparable to a loudly purring cat. Ever walked through a poultry exhibit at the county fair?
I was active with a chicken project in the city of Seattle, and the late-spring tours of city coops were interesting and entertaining, with owners taking pride in care and cleanliness of their facilities.