The tiny fish has a powerful sound, but it is more like someone talking loudly than a gunshot (One of world’s smallest fish found to make sound as loud as a gunshot, 27 February). Comparing decibels measured in air and water needs to be done with caution. It is like listening to the weather forecast in celsius and interpreting the numbers as if they’re in fahrenheit.
Trevor Cox
Professor of acoustic engineering, University of Salford
• The fact that forage-plant cultivation takes a lot more water than nuts doesn’t give us almond-lovers a free pass. I’ve long railed against almond milk, while still adding a few toasted almonds to my porridge. Thank you, George Monbiot, for making me see sense (We need to talk about water – and the fact that the world is running out of it, 4 March).
Sue Leckie
Edinburgh
