![]() ![]() In theory, in a sound field that we live it, the sound level decreases as a function of increasing distance from the sound source. There are also a couple of characteristics of the low frequencies of interest. It can also lead to emotions such as frustration and anger. As such, it can be explained as an unpleasant mental effect, characterized by irritation and distraction from one's conscious thinking. It can cause annoyance, educational disruption, sleep deprivation and a whole myriad of other effects that can be both physiological and psychological. There is no currently accepted "annoyance" scale that is both easy to assess and correlates well with how humans respond. In the first case, we are only interested in the health of our hearing mechanism, our microphones but stress from low-frequency environmental noise can be a problem. Let's make the distinction between the risk of hearing loss and stress effects. Noise is a stress factor that affects our psyche as well. Why bother if they cannot adversely affect our hearing, or if they are not loud enough to really bother us? Well, loss of hearing is not the only effect of noise. For this, they are dismissed as being not of importance even when people who are exposed, are greatly annoyed. Also, and when measuring noise in dBA to assess the risk of hearing loss or/and annoyance, results tend to be well below regulatory limits. People claim to “feel” them, rather than hear them, in their chests, or they have a funny feeling in their ears. We don’t perceive the low frequencies very well and much of its energy bounces off the eardrum and is never heard by a normal hearing individual. Here are some ranges of the frequencies of the different sounds: How do we define “low frequencies”? There is no accepted definition but in general, we do talk in those terms for noise with frequency components lower than 200 Hz. Those devices that are becoming ever more popular here, in Ontario, and even more in Europe! Some examples are the rumbling of a bus, the boom-boom of the subwoofer of our neighbor and the noise made by wind generators. In this article, we will be dealing with the latter type of noise. The sound of the wind blowing through the trees and even the cicadas on a hot summer's night can be quite nice, but some other sounds, even those that are not heard in the conventional sense, can be less than desirable. In our everyday environment, there is a wide range of extraneous, nice, and not so nice, noises.
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