1. Marcus Wallenberg Laboratory for Sound and Vibration Research, Kungliga Tekniska Högskolan , Teknikringen 8, SE-100 44 Stockholm, Sweden
2. A˚F Sound and Vibration , Kvarnbergsgatan 2, SE-411 05 Göteborg, Sweden
3. Swedish Meteorologic and Hydrologic Institute , Folkborgsvägen 17, SE-601 76 Norrköping, Sweden