The very best way to reduce noise from a washing machine is to position it correctly, make sure it is level and choose a low noise unit when purchasing a new one.
It should ideally be positioned on a solid ground floor as effective mechanical isolation is not practical as typical spin speeds are in the low frequency range between 10Hz and 20Hz.
Care should be taken using vibration isolators as they will generally cause the machine to vibrate excessively unless a substantial
concrete inertia block is installed as well. The machine may also 'walk' when on spin.
The worse location for a washing machine is on a lightweight upper timber floor where the resonant frequency of the joists
may be near the machine spin frequency. As a result, vibration amplification can occur. To minimise the effects in practice, the
washing machine should be positioned near the end of the joists, where
the deflection is at a minimum.
Other domestic appliances are likely to pose lesser problems. They
should be selected for quiet operation and should be installed so that
they are not in rigid contact with separating walls or lightweight