Can I record audio using an analog port?

The ATMega 328 processor has multiple 10 bit ADC (Analog to Digital Converter) ports. The default sampling frequency is 9KHz. But it is possible to configure the chip to read at 62.5 KHz with little loss of resolution.

One problem is transmitting this data through the UART. An uncompressed 10 bit 8 KHz signal would consume 80 Kbps at minimum.

I have found that using the Microphone Brick with the Seeeduino Stalker, that I could read only the positive part of the audio signal. Maybe it's something I did wrong, I don't know.