When’s the last time you stood still, and just listened? And when was the last time you heard no man-made noises? Perhaps on a back-country hike or a solitary mountain climb. Practically anywhere else, though, the odds are that you will hear noise generated by people or their machines. We fill the world with noise, from the hum of car wheels on pavement, to the buzz of electrical wires, or the far-off rumble of a passenger plane transiting above, or even the occasional technological banshee scream of a jet fighter, the world echoes with the sounds of our passage.
Even the ocean depths are not safe from our heavy footfalls. Sonar, whether military systems or used for depth finding, fills the waters with unnatural, and unsubtle, sound.
Noise has both physical and psychological effects. Extreme levels can cause damage to the ears, and acute physical distress. Noise effects have even been linked to cardiovascular disease and increased blood pressure.
Sound Intensity Levels
Decibel Level (dB) Source
140 threshold of pain: gunshot, siren at 100 feet
135 jet take off, amplified music
120 chain saw, jack hammer, snowmobile
100 tractor, farm equipment, power saw
90 OSHA limit – hearing damage if excessive exposure to noise levels above 90 dB
85 inside acoustically insulated tractor cab
75 average radio, vacuum cleaner
60 normal conversation
45 rustling leaves, soft music
15 threshold of hearing
0 acute threshold of hearing – weakest sound
The psychological effects of noise on people are difficult to describe. Psychological effects such as depression and nervousness are a result of the ear’s inability to adjust to sound. The eye has a very effective means of adjusting to light, but people never get “used” to noise. Instead, they usually adjust their mental attitude rather than hearing compensation. Subconscious frustrations can result when noise is endured, but the body system cannot adjust to it.
Imagine the effect all this noise has on the animals around us, who often typically are far more sensitive to sound than we are. High levels of noise are as an effective means of habitat destruction as bulldozing an area. Excessive noise affects predator-prey interactions, making it more difficult for sound-based predators to hunt, but more difficult for their prey to hear them coming.
Military sonar has been linked to the phenomenon of whales beaching themselves, perhaps disoriented from the intense bursts of sound. Some species of birds have started singing at night, rather than during the day. It is thought that the comparatively lower night-time noise levels make it easier for their message to be heard.
A classic example of pointless noise pollution would be the vuvuzelas, those giant hornlike noise makers so much in evidence at the FIFA world cup games in South Africa.
Humans are a noisy bunch. And like all human activities, this noisiness spreads to the world around us, polluting the environment. Noise pollution is harder to stop than light pollution, more pervasive. Yet there are things we can do. Better insulation for our homes is a start. Not only will this save money on energy costs, it will also help muffle the noises we generate. For constant industrial sounds, to it possible to generate a counter-noise, that will partially or fully cancel it out. Of course, this also requires power, but it may help in some circumstances. Unfortunately, there are so many of us that it will be difficult to alleviate the thunder of our passing. Perhaps the only hope for a quieter world lies in there being far fewer of us.