I came across an article about Eddie Woods and his acoustical swarm detection machine, the Apidictor. There are tons of beehives in my community and I wanted to get involved so I studied Eddie's work and applied an iphone app. to its end. Swarms are a means of bee's reproduction but they drive bee keepers nuts.
Eddie described a 'hiss' and a 'warble' occurring at different frequencies. The hiss occurs above 3,000hz after knocking the hive with an open hand. The warble occurs at around 250hz and is an indicator of hive problems.
Eddie associated a sharp hiss as a happy hive and associated the warble with a non-laying queen and/or a hive that maybe preparing to swarm. More info in step 3.
Using the iphone app n-track and a $5 mic from office depot I was able to filter the audio to required frequency band and listen for the sound indicators.
I worked with James Moore on his iphone App. dedicated to predicting SWARMS! - http://jmoore.me/swarmy/
Step 1: Hardware
I used a $5 maxell mic from office depot.
The benefit of using n-track is it allows real-time filtering... You set the frequency filters you're interested in and start listening in lieu of recording the sounds and then downloading them to a computer. The application is not the easiest to use and a bee keeper could benefit from an iphone specific application. How cool would that be!
James Moore took this task on and created a specific iphone app with the filters included. - http://jmoore.me/swarmy/
Step 2: Background & Results
Eddie described a 'hiss' and a 'warble' occurring at different frequencies. The hiss occurs above 3,000hz after knocking the hive with an open hand. The warble occurs at around 250hz and is an indicator of hive problems. Eddie associated a sharp hiss as a happy hive that had a laying queen and was not preparing to swarm. Eddie associated the warble with a non-laying queen. This could mean the queen is dead or the hive is preparing to swarm. There is a lot of interesting information in the article by Rex Boys.
I was able to record two different hives in the above 3,000 hz range and the knocks were followed by a nice audible hiss in most cases. Out of about 9 knocks I would get 3-4 strong hisses and more hisses could be detected after further sound amplification on the PC using the free software Audacity (its awesome). This makes sense as it is still winter here in Portland, Oregon and there should not be any preparations for swarming. I also recorded to hives in the 250 hz frequency and did not hear any warbling. There was a low drone. I'm looking forward to hearing some warbling as we move into spring in summer.
Here are some additional links:
Eddie Woods work by Rex Boys... what a cool guy.
The description on how to build the original Apidictor
Here is another guy who is interested in building an Apidictor
The Bee Hacker (got to love that title) has a nice summary of acoustical bee behaviors.
Original Apidictor patent