The book is intended for persons who have a noise problem, want to know what is causing the noise, and where it comes from. Once this is known most maintenance persons will be able to work out how to eliminate the problem. 10 years ago I started using laptop computers and good quality microphones to detect and eliminate noise hazards. The price of the instrument was measured in the thousands of dollars. 5 Years ago I started using video technology to overcome some of the limitations of walking around with a laptop. Now smartphones will do most of what I was doing 10 years ago with expensive equipment, and most of what I was doing with video. This book will show you how to use a Smartphone to detect noise. Choosing Microphones Using microphones Calibrating Smartphones dB Apps Spectrum analyser Apps Once detected and measured noise can then be eliminated. Another of my books "Eliminate noise Hazards" can be used with this book."