For a new project I need an audio live stream with very low latency (< 500 ms) from microphone to an online audience (web browsers).

So far I have tried a Wowza (trial licence) AMI on AWS (application with low-letency, otherwise standard settings), using Flash Media Live Encoder on the broadcaster side and the JWPlayer on the audience side. However, latency is very bad (20-30 seconds). Is there anything I can do to improve latency? I have searched this forum, but there is not much about audio only streaming. I can't imagine that a latency that high is normal for low latency live streams. Especially if it's sound only. Is there an encoder that is better suited than Flash Media Live Encoder?

Thanks for your help.