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/