Similarly, this type of non-invasive acoustic and vibrational monitoring has been used by doctors to get a better assessment of in vivo hip conditions so that they can better comprehend things like total hip arthroplasty (Glaser et al., 2010). Acoustic Signals

"Acoustic emissions are elastic waves generated by a rapid release of energy at a localized source. They are produced by events such as particle impact, gas evolution, boiling, phase transitions, precipitation. Some processes produce emissions that can be heard. A lot more emit either outside the audible frequency or at too low an intensity to be heard (McLenna, 1995, p.338). Using non-intrusive acoustic monitoring is definitely a way to monitor an entire structure continuously and effectively (Wu & Abe, 2003). Acoustic signal-based monitoring can assess individual entities and mechanisms or total structures, pinpointing abnormalities, failures or red flags which need attention (Wu & Abe, 2003). It provides experts with truly valuable information that allows for focused research and further evaluation, as well as improve the timing of repairs or rehabilitation, or help to tweak and adjust maintenance budgets (Wu & Abe, 2003). Managers, scientists, policy-makers and members of society should view this form of technology as a management tool and illuminator which can shed light on the needs of communities, individuals and structures, allowing one to better manage the integrity of these things which deeply matter.

The possibilities for acoustic-signal-based monitoring are truly boundless as they are able to detect things that the human ear is completely incapable of doing. A shining example of the value and potential of this form of technology is with the monitoring of live chick embryos. At this time, the technology is semi-invasive, but in a few years this will surely change. The process demonstrates how acoustic signal monitoring can be used with success to observe and assess the development of chicks which grow into chickens and which have direct impact on feeding America and the expansion of the poultry industry as a whole (Liang et al., 2011). In the study, "Monitoring of live chick embryo based on acoustic and vibration signals with a new semi-invasive technology" (Liang et al., 2011) the researchers determine the healthiness and rate of development of a chick embryo by making a small hole with a pin at the top of an egg so that the heartbeat signal after amplification is tracked (Liang et al., 2011). A microphone is installed over the hole made, helping to distinguish the live embryo and making it distinct from a small and weak embryo (Liang et al., 2011). This type of data can help the researchers determine the whether the embryo is alive or not, something that is absolutely crucial for development of the poultry industries.

Yet another group of researchers decided to use acoustic monitoring for benefit in the animal kingdom. The study, "Target Classification and Localization in Habitat Monitoring" by Wang and colleagues seeks to determine if acoustic signal monitoring through the use of sensors can be used to recognize and locate animal calls (2003). This form of habitat monitoring has two objectives, "The first part is to determine whether observed animal calls are of the specified type using their spectrograms. Each type of animal call has its own characteristic spectrogram which is input to the system. The classification of an observed acoustic signal is determined by the maximum cross-correlation coefficient between its spectrogram and the specified characteristic spectrogram [3]. The second part is to locate the calling animal when its call is recognized" (Wang et al., 2003). Since the animal kingdom relies so heavily on the use of sounds as a form of communication and in their development and habitation, acoustic-based signal non-intrusive monitoring can be incredibly useful. As stated earlier, human beings have an extremely limited hearing ability, particularly when compared to the animal kingdom. In order to gain a better understanding about animal needs and behavior, acoustic-based monitoring can definitely help scientists shed some light on the multi-faceted range of processes.

For instance, the research study, "Acoustic Sensor Networks for Woodpecker Localization" by Wang and associates admits that sensors offer some of the most valid, effective and non-intrusive ways to study animals. Studying animal behavior...

In this experiment the data gathered relied upon the vocalizations of woodpeckers, using four microphones arranged as a square (Wang et al., 2005). "All four audio channels within the same acoustic array are finely synchronized within a few micro seconds. We apply the approximate maximum likelihood (AML) method to synchronized audio channels of each acoustic array for estimating the direction-of-arrival (DOA) of woodpecker vocalizations" (Wang et al., 2005). Apparently, the work of Wang and colleagues feel that they uncovered the fundamental connection between microphone spacing of acoustic arrays and the solidity of woodpecker vocal tracks given the typical noise and interference that one will encounter when trying to record woodpeckers (2005). Experiments like these which depend so heavily on the work and interactions of acoustic signals monitored in a non-intrusive fashion, can truly illuminate a tremendous amount about animal research.
The biological areas of the sciences are not the only ones that can benefit from acoustic-signal monitoring -- though this arena is ideal for this form of monitoring as it forces scientists and researchers to find a means of detecting the sounds of energy and movement, things connected to all forms of life. For example, numerous fields of industry can benefit from these processes and technologies because so much of the correct functioning of their machine's mechanisms is connected to the acoustic signals given off. "Acoustic Emissions (AE) and surface vibration monitoring technologies, are promising non-intrusive approaches to online monitoring of industrial tumbling mill process and machine condition" (Meech et al., 2005). This allows technicians to receive valuable feedback as to whether or not their processes are running effectively or not or what certain malfunctions indicate and what needs to be changed. This data is so valuable as it can be received without taking apart equipment but via the most non-intrusive form of monitoring.

The potential benefits of acoustic-based monitoring truly are boundless. For instance, some companies use acoustic technology which examines and assesses the noise caused by sand grains on the pipe wall on the radius of a bend: "This noise can then be used to calculate sand production rates based on knowledge of background noise, flow rate and particle size. Acoustic sensors provide an immediate response to any changes in sand production by detecting acoustic signals emitted when a sand particle hits the pipe wall. Benefits include easy installation, the immediate detection of sand production, and low power consumption" (emersonprocess.com). This demonstrates how the technology can be used for the most ideal results possible, saving time and money.

Aside from immediate financial savings, acoustic-based non-invasive monitoring can also assist with the maintenance of certain forms of infrastructure and support. For instance, the study, "On the opportunity to use non-intrusive acoustic emission recordings for monitoring uniform corrosion of carbon steel and austenitic stainless steel in acid and neutral solutions" attempts to shed light on the issue of the uniform corrosion of steels (Jaubert et al., 2005). The researchers acknowledge how this corrosion is very widespread and is the cause of the destruction of a range of industrial parts which are responsible for a large amount of economic and environments failures (Jaubert, et al., 2005). While it's true that classic corrosion formula can predict and shed light upon the average rate of corrosion for certain materials, the reality is that these formulas cannot give one an instantaneous value of corrosion in real-time. However, using acoustic signaling in connection with the release of energy within an item that's creating a transient elastic wave propagation, corrosion information can be obtained in a quantitative fashion (Jaubert et al., 2005).

Essentially the researchers found that, " it appears clearly that acoustic emission measurements are in good correlation with aggressiveness of the corrosive media, and a semi-quantitative correlation is obtained between AE activity and corrosion rate for austenitic stainless steel. Whereas initial surface conditions greatly influence the acoustic activity, AE monitoring appears to be a rewarding technique for detecting corrosion rate evolutions during process modifications" (Jaubert et al., 2005). The results of these findings are extremely influential for the world at large. Essentially, there's a more effective way for determining the real rate that something is corroding: this means that there can be greater preventative measures and more precise maintenance measures for public safety and public efficiency, as many of these industrial materials are used as support for bridges, highways, trains, locks, gears and other items. It's the responsibility of public leaders to make sure that they are strong and stable when in use, and acoustic-based non-intrusive monitoring is a viable option to receive this information -- as none of these structures have to be destroyed or invaded to gather this info.

Assisting with maintenance in industrial machines truly is one of the overwhelming benefits that acoustic-based non-intrusive…