Change some of your parameters per this sample config:
[general]
duration = 0
bufferSecs = 5
reconnect = yes
[input]
device = plughw:1,0 # sound device
sampleRate = 44100 # 22050 or 44100
bitsPerSample = 16 # only use 16
channel = 1 # use mono
[icecast2-0]
bitrateMode = cbr
format = mp3
bitrate = 16
server = audio-in.liveatc.net
port = 8010
sampleRate = 22050
lowpass = 3500
mountPoint = ASSIGNED-BY-LIVEATC
password = ASSIGNED-BY-LIVEATC
name = FEED-DESCRIPTION
description = FEED-DESCRIPTION
url =
http://www.liveatc.netgenre = ATC
public = no