How to record voice in a browser?

You can interact with a client's microphone using flash, this will require permission from the user. For implementation details please visit my reference.

Reference: http://fmsguru.com/showarticle.cfm?articleID=25

The ideal solution would be getUserMedia and the Stream API. Unfortunately, it is currently not well-supported across modern browsers. As of June 14, 2012 the only browser confirmed to have support according to caniuse.com is Chrome 21. Others appear to be working on solid implementations.

Until native support arrives, Flash can access and record both audio and video.