Use 'belt out' to emphasize strong emotions behind the singing, like joy, excitement, or pride.

Emotional Intensity

'Belt out' is casual and might not suit formal or classical singing contexts.

Informal Settings

Use 'belt out' when someone unexpectedly starts singing loudly, as in a spontaneous burst of song.

Use 'belt out' to describe forcefully expressing oneself in spoken circumstances.

Remember 'belt out' can apply to spoken words, not just singing, to convey volume and assertiveness.

'Belt out' in speech implies informality and may not always be appropriate in formal or quiet settings.