No, a HPU operates relatively quietly at 65dBA at 1m, significantly below the noise levels of an equivalently-sized diesel genset at approximately 85dBA. Whilst its not silent, its 10 times quieter than a diesel generator meaning that its ideal to operate in built up areas or on TV and film production sets. Note that because dBA is a logarithmic scale, used because of the wide range of human hearing, 20dBA makes a lot of difference. The definition of dBA means that an 85dBA noise is 10 times more powerful than a 65dBA noise.