That is the question we got asked today. Petrol generators are the noisiest type of generator you can hire, but are usualy used for plant equipement & tools. Diesel generators are by far the quietest of the generator family, as these are normally used at events and functions the noise must be kept to a minimum etc.� The reason for this, is because the come silenced which means even upto 4o kva the noise produced is less than 73 dba @ 7m. Of course if you want a really silent generator you could switch it off, however that would defeat the point!