Domestic harmony

SIR – Wasps beat their wings at a frequency of 216hz, which is equivalent to the musical note A below middle C; so if Kim Halliday (Letters, January 17) has a friend with perfect pitch, together they can test out the theory that the mysterious buzzing noise in the house comes from a wasps’ nest behind a wall.

Marcus Dain

Fyfield, Essex

SIR – I traced the low-level humming noise in our house to our rotary line dryer in the garden.

This has a hollow metal tube with evenly spaced holes as its main component, and acts like any wind instrument when the wind blows. You can change the note by altering the height of the drying canopy, or lower the canopy and put a cover over it to stop the noise altogether.

Sheila Pearce

St Austell, Cornwall