If you find it hard to identify a shop that sells mufflers, perhaps a cap that goes over your baby's ears may be the next best thing? That way the baby can still hear but the sound would be muffled a little and it won't be all disorientated.

Loud sounds which are a form of environmental stress can affect the magnesium levels of anyone therefore increasing the deficiency that they already suffer from (majority of the world's population is magnesium deficient according to a 2006 report by the World Health Organization). So another tip would be to increase your magnesium intake. What's funny is that sensitivity to noise is also brought on by magnesium deficiency. A real chicken and egg thing. http://www.ctds.info/noise-sensitivity.html

A good source of magnesium is Extra Virgin Magnesium Oil which can be consumed both orally and applied on the skin which makes it suitable for all ages.