**2. Noise control in literature**

Literature is full of excellent works related to noise control. When one looks more in depth, some useful pieces of information can be derived. In order to do so, it is useful to picture the connection between the several different topics related to the "noise control" one.

When referring to **Figure 1**, it is possible to see that seven principal areas are related to the keyword "noise control," namely (in order of numerical importance given by literature papers:

1.noise related to electronic devices

**Figure 1.** *VoS Viewer picture of the first 2000 records available in Scopus, using the keyword "noise control".*


However, it is clear how many treated topics are not cross-linked together. As example, materials and metamaterials are only linked with vibrations and mechanics and not to the other fields. In the same way, speech perception and hearing impairment are related only one to each other but not for example with quality control, control systems, etc.

From **Figure 2**, it is interesting to notice how, when using a density analysis, the most important parameter related to noise control is related to human (yellow spot at the right), then to quality control (center), and then to controllers and how to control noise (left). When specifically focusing on noise as keywords, this cross-linked relation between "noise" and "human" topic becomes the most relevant (**Figure 3**). Here, the connection between noise, human, quality, and the psychological effect is assessed, confirming the initial hypothesis.

This demonstrates how more science is needed, especially cross-disciplinary research studies that make it possible to solve problems, to formulate new hypotheses, and to confirm or negate the ones that are still open.

The vision of this book is then to continue on the path of innovation in science considering different issues, apparently diverse one from another, but with a common idea: implement the knowledge on noise control and spread it.

With this in mind, different topics are here handled:

a.control techniques and methods [1]

*Introductory Chapter: Is Noise Really Important? Should It Be Controlled? DOI: http://dx.doi.org/10.5772/intechopen.108435*

#### **Figure 2.**

*VoS Viewer picture of the first 2000 records available in Scopus, using the keyword "noise control" – density visualization.*

#### **Figure 3.**

*VoS Viewer picture of the first 2000 records available in Scopus, using the keyword "noise control" – specific connections.*

b.EVAC [2]

c.Pollution during COVID pandemic [3]

d.Outdoor Barriers [4]

e.Mapping [5]
