@Lola,
We used to hold a fart lighting competition every Boxing Day but after Mrs Jolly won three years on the trot we gave it up. Nobody could hold a candle to her. Not without risking getting singed eyebrows. And she set the Christmas decorations alight.
An international survey found that men fart 35 times a day on average and ladies 31 times. So it is reasonable to assume that in a two hour long, intimate
tete-a-tete in a restaurant a lady would likely have farted 2.58 times allowing that bubblers lasting less than 10 seconds are counted as one. A restaurant with a hundred diners of equally mixed gender is producing (35 x 50 + 31 x 50) divided by 24 farts every hour which is the direct cause of the discreet whirring sound.
If genuine turtle soup is the starter the figures increase alarmingly and eateries which serve the Galapagos delicacy have gas masks hanging on the back of the chairs. In cheap joints fans are employed to diffuse the farts.