A double sided hexagonal slide rule with seven edges is detailed for interference of noise waves based on a benchmark solution. A slide rule is developed for characterisation of interference of noise waves due to difference of power of two intensities. The standard sources of noise waves (sun, light, sound, heat, electricity, fluid and fire) are considered in the slide rule depending on their speed of noise interference. A slide rule calculates noise interference from standard noise measurement equations and their units. The grades and colour flags of noise are notated to the slide rule based on psychological feeling for sensation and perception of noise.