It may be bad manners, but eating noisily could be good for your waistline. Research has shown that we eat less when we can hear ourselves chew.
Ryan Elder, of Brigham Young University in Utah in the US, said: "Sound is typically the forgotten food sense. But if people were more focused on the sound food makes, it could reduce consumption."
Dr Elder made the finding after asking several groups of volunteers to do taste tests and measuring how much food they ate.
In one, 71 students were asked to rate the taste of a type of pretzel while wearing headphones. Half heard loud noise, which drowned out the sound of their chewing, and they got through four pretzels each. The others were able to hear themselves eat and only consumed 2.8 pretzels, on average.
Dr Elder explained: "The effect may not seem huge - one less pretzel - but over the course of a week, month, or year, it could really add up."
In another experiment, 156 students were asked to rate biscuits made of pitta bread.
Before they ate them, half of the volunteers read packaging which described the crackers as "crispy" while the others were simply told they were "tasty" and "delicious". Both groups were then given the same biscuits to eat - but those who had been made to think of them as being crunchy ate fewer.