Hardware

• Acoustic pickup for reading string vibration via audio input: https://www.google.com/search?aq=f&ix=iea&sourceid=chrome&ie=UTF-8&q=acoustic+pickup
• Audio input to Android phone via headphone port:
  • https://www.youtube.com/watch?v=sz-9mxWa2VA

Android

More portable but maybe harder, should start with laptop approach (below)

Spectrum ("EQ") Android apps

• $2: https://market.android.com/details?id=com.julian.apps.SPLMeter&hl=en
• Free: http://www.androidzoom.com/android_applications/music_and_audio/spectral-audio-analyzer_bbhl.html

Android graphing/audio libraries and code

• Charting: http://code.google.com/p/chartdroid/
• Audio input processing: http://stackoverflow.com/questions/7686898/reading-data-from-a-microphone-in-android-to-process-it-online

Laptop approach

• Android lacks low-latency audio interfaces, so maybe better to just use a laptop
  • guitar pickup direct to microphone input
  • use a simple Processing app

Related projects/work

• Eddy Flux (via Mathew) - http://atmos.seas.harvard.edu/lab/brazil/lbaflux.html
• Page 4 (via Adam) - http://nadp.sws.uiuc.edu/lib/brochures/nitrogen.pdf