Most of the hearing protection I've used when shooting seemed designed to disrupt the sound wave move than actually reduce it.
You can achieve reasonable short-term protection by holding your hands flat over your ears. It doesn't reduce the subjective volume, but it does [anecdotally] prevent subsequent symptoms that indicate temporary or long-term damage has occurred.
> You can achieve reasonable short-term protection by holding your hands flat over your ears.
Not flat... that won't do much. They must be cupped... basically you make a letter "C" with your hands then old that up to your ear with your side of your palm (pinky side) resting on your temple.
This will deflect the sound wave around your ear. Old-school artillery trick.
