Your cover story (Shhhhh, 13 August) usefully draws attention to the health problems aggravated by loud or unexpected noises. I believe the contribution of emergency vehicle sirens to anxiety, depression and other diseases is ignored, because the origin of these diseases is multifactorial. A fruitful research area, now that most vehicles embody sophisticated electronics, would be to look at more subtle and focussed ways of warning drivers of approaching emergency vehicles.

Note: New Scientist edited this letter, replacing ‘because the origin of these diseases is multifactorial’ by ‘due to their multifactorial origins’, which I would not write myself.