On Jan 16, 2008, at 6:24 PM, Victor Fraenckel wrote:

> I would like to get your guesstimate of smallest size audio
> recording/playback device that could be built using today's  
> technology.

Microphone + 8-pin microcontroller + microSD flash card ? This  
assumes you can double-buffer data to the flash, which I'm not too  
sure of.  A high density EEPROM or "dataflash" may be more likely to  
have on-chip buffers, and is approximately the same size.   Power  
supply would probably be the limiting factor.


> The device should be able to record at least one to two minutes of
> speech and play it back (on demand) with reasonable fidelity.


Recording time effectively unlimited. 2G (max size of SPI-mode SD  
access) is several hours of CD-quality stereo audio; 60+ hours of  
phone-quality mono audio (without compression!)  I've been toying  
with the somewhat mind-boggling thought that a device about the size  
of a wristwatch could literally record a full day (several days?) of  
the interesting sounds a person runs into, for purposes of news- 
gathering, documentaries, or personal memory augmentation.  At that  
point, the interesting problem becomes SEARCH and RETRIEVAL of the  
massive quantities of digitized audio, which seems to me like a  
relatively hard problem indeed.

BillW


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