I worked on the Irisys People Counter:

http://www.irisys.co.uk/

which can track people reliably. They are quite expensive, though.

Goniometers are typically used for that sort of measurement, in biomechanics.

Interface details?

Interface an electret microphone and amplifier to an analogue input.

If your ADC sampling rate is low enough (say 8 kHz) you should be able to do that.

PWM is output only! Look it up.

Thanks Leon. Why do you think ultrasonics would not work ? Can anyone suggest a better method ?

Thanks
T

People don't reflect sound very well.

PWM uses an output pin!

You could connect the microphone unit to an ADC input and transmit the digitised speech to the other Arduino via Sparkfun nRF24L01+ modules.

I don't think that ultrasonics will work very well for sensing distance with people.

A JTAG I/F, about $50, is needed with that SFE board. The $99 XC-1A board with a four-core 1600 MIPS chip on it includes the JTAG I/F.

PCBTrain:

http://www.pcbtrain.co.uk/

The Arduino hasn't enough performance for that sort of application.

I'd be inclined to use XMOS chips:

http://www.xmos.com/

They have the performance, and are often used in high-end digital audio applications.

Mega Electronics stocks 0.8 mm and 1.0 mm:

http://www.megauk.com/pcb_laminates.php

The Adafruit motor shield is very easy to use:

http://www.adafruit.com/index.php?main_page=product_info&cPath=17_21&products_id=81

It's supplied as a kit, but it only takes 20 minutes or so to put it together.

Of course it is!