Is there any ready-made application that allows one to stream audio, over WiFi to from phone's microphone to a configurable IP-address and port-number ?
Have come across several applications that do the reverse, and some that are very purpose specific, i.e. baby-monitor, which do not fit my purpose.
Yes there are. Some which I found are for gaming live streaming like YouTube Gaming, Mobcrush & Twitch. Some for screen mirroring and streaming like Screen Stream Mirroring Free. Some streaming videos and audios like AllConnect - Play & Stream which supports DLNA/UPnP. Some also make your android a UPnP/DLNA streaming server like BubbleUPnP UPnP/DLNA, MediaHouse UPnP / DLNA Browser, Plex & BubbleUPnP for DLNA/Chromecast.
Update: Also there Voip over lan apps like Wi-Fi Talkie FREE, WiCall : VoIP call, Wifi call & Intercom for Android,. There is app for streaming android mic to Icecast servers called Cool Mic. Another streaming via HTTP/RTSP called LANmic and another called RtpMic.
Sorry I can't post more than 2 links with my new account. I posted the exact names of some examples though. I'm sure there are more but these were on the top of the lists and with massive number of users.