# How to derive a rate (e.g. water dripping) from an audio file

I want to learn how to go about analyzing some audio files I have acquired. Let's say the files contain some sort of repeating sound (e.g., water dripping), and I want to derive the pattern of the repeating sound. I use R for programming and analysis and have briefly introduced myself to the tuneR and seewave packages, but I am open to any answers about how such an analysis should be conducted.

To make my question more concrete, let's say I have a 2 hour audio file of water dripping and I would like to be able to select some point or interval in the file and know the drip rate. I will be pursuing further processing (e.g., finding times when the drip rate is most steady, fastest, slowest, etc.), but right now I am looking to learn how to get started with this task.

Specifics of my audio files:
.Wav files
Sampling rate: 44100 Hz
Bits: 16
Stereo


I briefly read about Fourier transforms, but due to my lack of knowledge and my rudimentary understanding of terminology, I am unclear if a Fourier transform would be appropriate starting place for this task. I also briefly read about subcarriers, envelopes, and autocorrelation, but it quickly became clear to me that I could benefit greatly from some guidance before I start investing too much time learning about and introducing myself to the incorrect topics.

• sounds like the same problem as "beat detection" in music. like deriving the rate of whacks on the kick drum or something else. – robert bristow-johnson Jan 3 '14 at 20:19