bs-spectrum is a simple FFT spectrum analyzer application.
This application calculates FFT (Fast Fourier Transform) of the sound which is recorded by the iPad & iPhone's internal mic. The calculated data is displayed as graph.
I do medium voltage switchgear maintenance and repair in my job (13.2KV down to 480V). My partner thought that he heard an air leak in the gear one day, which is a sign of arcing. That range is gone in my hearing, so I used this app with my iPhone5 on the main 13.2KV breaker and took a screen shot of it, which showed a hard spike at around 10KHz. We singled up the plant and shut down that feeder the following weekend and pulled out the main breaker for maintenance... We found evidence of arcing inside the arc chutes. We cleaned, lubed, and tested the breaker and put it back into service. Afterwards, I ran the app again as before, and took a another screenshot (over-layed) on the first one.... this showed the spike was absent now. We used this comparison graph to quantify our results to upper management, which validated the expense of a weekend shutdown. Great app!
Suggestions
I like the app,nicely done, but I would really like to be able to specify a number of samples and then average the amplitudes at each frequency ... This would enable me to pick out dominant frequencies and get rid of the random noise.
Useful app, but...
This is a very useful app, but i wish you were able to hold the iPad in portrait view since the mic on the iPad is on the top... The app doesn't auto-rotate.
Very useful
This app will be very nice to have for when I tune rooms for sound systems. I would have given 5 if I could increase the db level to monitor the frequencies. I need at least 90db
