Record Audio to your Audino Mega SD card.
The audio file can be played back on a standard audio application or analysed byte by byte.
This Instructable will show you how audio input can be repeatedly added to a 512 byte buffer and then transferred to a SD card in real time. The period recorded can be altered.
The sample rate is 9.4 KHz and the wav file output 8 bit, mono. Whilst not hi-fidelity, the sound quality is perfectly adequate.
The recorded wav file can be saved as tabulated data. It can also be displayed as a simple scrolling graph on the monitor.
All files are time stamped using a unix time code sent from the serial monitor.
The inspiration for this article came from reading Amanda Ghassaei: https://www.instructables.com/id/Arduino-Audio-Inp...
My latest program update at the end of this instructable, increases the sample rate to 19 KHz with a significant improvement in audio quality.
You may also be interested in my instructables on:
A high speed Arduino Oscilloscope: https://www.instructables.com/id/Arduino-High-speed...
Playing wav files from the Arduino: https://www.instructables.com/id/Arduino-playing-wa...
Inevitably SD card technology has already improved. I have tested with a Sandisk Ultra 8GB sd card. This is significantly faster than the Kingston 4GB card I started with. Using my updated software I am able to record at 38.3KHz, with no degradation in quality. (4/8/2014)