I only get a bad taste in my mouth if my stomach is upset when I burp.
If air bubble leaves my stomach I can muffle the burp or allow it to be louder. If I have to force an air bubble out because it's sitting on the verge but won't go on it's own (in which case it's uncomfortable and needs to be forced out) it will usually come out louder because I can't switch to muffling before it's made noise.
I don't think the volume is something people have complete control over (just partial) even if they can influence if it's likely to be loud or quiet.
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