DIY laser mic, visualize sound waves, iPhone 5 DAC

Here are some recent audio-related items that caught my eye:

Build a Laser Microphone: Here's an interesting project offered to those DIYers who want to "eavesdrop on conversations across the street." All it takes is a laser pointer, an npn phototransistor, a headhone amp, and some miscellaneous parts.

DAC in iPhone 5: If you're curious about what DAC chip was used in the iPhone 5, DIY electronics repair site iFixit offers a look, up close and personal. (It's apparently a "338S1077" Cirrus Logic audio codec.)

Making Sound Waves Visible: Here's a video demonstration showing how to use a lock-in amplifier - along with a mic and LEDs - to coherently detect and analyze sound waves.