von atmel selbst gibts da auch noch ein paar tips in folgendem dokument:

AVR335: Digital Sound Recorder with AVR and DataFlash (20 pages, revision C, updated 04/05)
This Application Note describes how to record, store and play back sound using any AVR MCU with A/D converter, the AT45DB161 DataFlash memory and a few extra components

http://www.atmel.com/dyn/resources/p...ts/doc1456.pdf