A survey of complaints about infrasound and low frequency noise has been carried out. 198 persons reported their troubles in a questionnaire. Their verbal reports often described the sound as deep and humming or rumbling, as if coming from the distant idling engine of a truck or pump. Nearly all respondent's reported a sensory perception of a sound. In general they reported that they perceived the sound with their ears, but many mention also the perception of vibration, either in their body or in external objects. The sound disturbs and irritates during most activities, and many consider its mere presence as a torment to them. Many of the respondents reported secondary effects, such as insomnia, headache and palpitation, which they associtated with the sound mainly because it occured at the same place as the sound. In a majority of the cases, only one or a few persons can hear the sound, but there are also examples, where it is claimed to be audible to everybody. Typically, measurements have shown that existing limits (and hearing thresholds) are not exceeded. The investigation leaves the key question: Are the troubles induced by an external sound or not, and if they are, which frequencies and levels are involved? The feasibility of a study of this is supported by the results.