I need to acquire and save to a non-volatile memory a voice message (speech) from a microphone. The solution should be minimized as number of components, PCB space and cost.
It's a speech application, so 8kHz/8bit is more than sufficient and the quality expected should be similar to a phone call.
I already read the AVR335: Digital Sound Recorder with AVR and DataFlash and it's a very good starting point.
In that AN the analog signal from microphone is acquired with internal 10-bit ADC and reduced to 8-bit samples with a simple operation (truncation).
My question is: what could be the quality of the recorded audio signal with this approach?
I know complex circuits with microphone input have AGC amplifier in order to compensate different distances and volume levels of different speakers. I don't need high-fidelity audio, but I'd like to hear the message such that it will result understandable (similar to a phone call quality).
The speaker should always speak at the same distance (15-20cm) and with a high volume, but as you can understand the effect of different speakers will be different.
Is the simple approach described in AN from Atmel suitable with my application?
Do you suggest other low-cost solutions?