What is another word for sounding off?
Pronunciation: [sˈa͡ʊndɪŋ ˈɒf] (IPA) 
When someone is "sounding off", it means they are speaking their mind in an authoritative and often confrontational way. There are several synonyms for this phrase such as speaking out, expressing oneself, airing one's views, venting one's feelings and stating one's opinions.
Other synonyms include standing up for oneself, asserting oneself, declaring one's beliefs, championing a cause and taking a stand. Some may use the phrase "voicing one's concerns" when they want to stress the importance of constructive criticism.
Overall, whether one is "sounding off" or "speaking out", it is important to be articulate and concise when conveying one's message. It is also important to avoid being rude or aggressive, instead, striving to convey a point of view with authority and clarity.
