1. Vibrationdata 1 Special Topic 1 Processing Sound Files Matlab & Python The most interesting sounds are those which have sine tones

2. Vibrationdata 2 Record Sound with Your Device

3. Vibrationdata 3 For Android Users Allows sound recordings to be transferred in *.ogg format via Email. Similar apps appear to be available to iPhone & Apple Devices

4. Vibrationdata 4 Audio File Formats http://en.wikipedia.org/wiki/Audio_file_format There are many types of formats. Common ones are: *.mp3 - MPEG Layer III Audio - compressed format - popular for CDs *.ogg - Ogg Vorbis - open source - compressed format - Archos and Samsung *.wav - large file sizes, convenient for conversion to ASCII text

5. Vibrationdata 5 Conversion Need data in *.wav format for digital post-processing Use conversion utility such as: Online conversion: http://www.zamzar.com/ Download freeware audio editor: http://audacity.sourceforge.net/

6. Vibrationdata 6 CRJ-900 – Cabin Noise Example

7. Vibrationdata 7 Matlab Utility vibrationdata > Miscellaneous > Sound File Editor > Read wav File Read wav file then Export to Matlab (one or two channels) Sample file: crj900.wav

8. Vibrationdata 8 Sample Sound File, Two Channels File: crj900.wav - noise inside aircraft cabin due to engines, etc. Read into Matlab. Then Export to Workspace

9. Vibrationdata 9 Matlab Fast Fourier Transform vibrationdata > FFT - input one of the sound channels Each turbofan engine has two rotors. N1 Fan - 104 Hz N2 Core - 252 Hz Engines were at 85% power for this recording.

10. Vibrationdata 10 Python Utility vibrationdata > Miscellaneous > Sound File Editor > Read wav File Read wav file then Save to Text (one or two channels) Sample file: crj900.wav

11. Vibrationdata 11 vibrationdata > FFT - input one of the sound channels Python Fast Fourier Transform