What is noise: types and examples

When we hear the word “noise”, the image possibly of some type of device that produces a great sound comes to mind and in part like this, although the truth is that within the noise itself we can find different types as you say. We explain below, also mentioning several examples in this regard.What is noise: types and examplesNoise is an oscillation of the air that, when it hits the eardrum, is interpreted by the ear and the brain. We generally speak of noise due to unnecessary and unpleasant sounds. Like sound, it is characterized by its frequency, its speed of propagation and its amplitude, thus generating the various types of noises that exist. Frequency We are talking about bass sounds (low frequencies) or high tones (high frequencies). The audible range is between 20 Hz and 20,000 Hz, that is, between 20 oscillations per second and 20,000. Below 20 Hz we speak of infrasound (windmill for example) and above ultrasound. Propagation speed is 340 m / s. When it is reflected in an obstacle (a wall, a curtain of trees …), we speak of a “Echo”: we hear the noise attenuated but as it was. When it is reflected off the walls, the floor, the ceiling of a room, we speak of “reverberation”: we can no longer recognize the initial noise; we just have a noise that continues and gradually disappears.Amplitude is measured in decibels (dB). The ear does not hear noises of all frequencies in the same way and tends to attenuate low-frequency noises. To take this phenomenon into account, the devices (sound level meters) have an electronic circuit that also makes it possible to attenuate these low-frequency noises. When we measure noise, it is no longer how it exists, but how it is heard, we speak in dB (A).The types of noise From the aforementioned, we can make this classification, into four types: Continuous Continuous noise is produced constantly, for example, by machinery that continues to operate without interruption. This could come from factory equipment, engine noise, or heating and ventilation systems. This type can be measured for a few minutes with a sound level meter to get a sufficient representation of the noise level. But if you want to analyze the noise further, you should look for a sound level meter with octave band analysis. Octave bands allow noise to be divided into its separate frequencies. This information will tell us exactly what frequency is causing the noise. It may even be better to investigate noise with 1: 3 octave bands, which can provide even more detail about the frequency content of the noise you are measuring. Intermittent Intermittent noise is a level of noise that rises and falls rapidly. This could be due to a train passing by, factory equipment running on cycles, or airplanes flying overhead. We measure intermittent noise in a similar way to the above, with a sound level meter. However, we also need to know the duration of each occurrence and the time between each one. To obtain a more reliable estimate of the noise level, it must be measured over multiple occurrences to calculate an average. If an integrating-averaging sound level meter is being used, it will do the calculation and present it in terms of a LAeq. Impulsive Impulsive is most commonly associated with the construction and demolition industry. These sudden bursts of noise can be scary because of their quick and surprising nature.Impulsive noises are commonly created by explosions or construction equipment, such as when a construction site is being constructed, a building is being built, or your next door neighbor doing some DIY on a Sunday morning. To measure impulsive noise, you will need a Sound level meter or personal noise dosimeter that can calculate peak values. Low-frequency Low-frequency noise is part of the fabric of our everyday soundscape. Whether it is the background hum of a nearby power station or the roar of large diesel engines, so it is something that is constantly present in our lives. It also happens to be the most difficult to reduce at its source, so it can easily spread for miles around. To measure it you should use a sound level meter with one-third octave band analysis, so you can analyze the lows. frequencies that compose it.