Loud music, a passing aeroplane, street noise or quarrelling neighbours: one person can hear over it, for the next the background noise is bearable and still others feel very annoyed. Everyone experiences noise differently. The perception of noise depends both on the situation in which we encounter the noise and on whether we are positively disposed towards the "noise source". If we find the source sympathetic or can even estimate the duration of the noise, then we accept it much more calmly.
However, since we cannot switch off our ears, they are ready to receive at virtually any time. Around 15,000 hair cells pick up sounds and then send signals to the brain.
How do you measure noise?
Regardless of whether it is a soft whisper or a deafening jackhammer - physically speaking, all sounds consist of sound waves. Sounds are created when a body vibrates. In the process, particles in the air as well as in the water are set into wave-like motion. Sound events and their strength are described in the unit of measurement decibel (dB). Where 1 decibel indicates the weakest sound audible to the human ear.
At what limit are noises perceived as noise?
When we whisper, the noise level is around 40 decibels. Major roads or even a noisy open-plan office, on the other hand, quickly reach a sound level of 80 dB. While noises up to 65 decibels are usually described as "normally" loud, constant exposure to sound at a volume of 80 - 85 dB can cause permanent damage to hearing. We are particularly sensitive to noise during sleep. Values as low as 25 dB are enough to disturb our sleep. The German Professional Association of Ear, Nose and Throat Doctors, the Federal Ministry of the Environment and the World Health Organisation (WHO) assume these limits.
The sound pressure and its pitch determine how disturbing the volume is perceived. Here, the air pressure fluctuations per second are measured in hertz. The higher the frequency, the higher the human hearing assesses the noise. Surprisingly, low and very high tones seem less loud than tones of medium frequency. As a result, the ear perceives sounds of different frequencies at different sound pressure levels as being equally loud. At a value between 120 and 140 decibels, the sound waves are perceived as pain.
Note: An overview of noise-related limit values according to the Federal Immission Control Act can be found in our Table of measured values.
However, the sound scale does not increase constantly, but logarithmically. An increase of only ten decibels is perceived as twice as loud. Even small decibel reductions are therefore a clearly noticeable contribution to noise reduction.
How does noise affect physical & mental health?
Noise (Lp ) affects the entire organism and puts us on alert. This means stress for the body. This inner state of arousal is a remnant of our ancestors' readiness to fight and flee. If the noise level rises to 60 decibels or higher, the human body releases the stress hormones cortisol and adrenaline, for example. This increases the heart rate and blood pressure. But noise not only changes the hormone balance, it also affects metabolism and brain wave activity. Continuous noise can therefore lead to permanent hearing damage and promote depression. The World Health Organisation (WHO) even classifies noise as the second greatest environmental hazard to physical and mental health in Europe.
These physical reactions caused by noise are possible:
- Increase in heart rate & associated cardiovascular problems
- Constriction of blood vessels & decrease in skin temperature
- Hearing disorders up to and including tinnitus
- Tension of the musculature
- Headache
- Circulatory disorders
- Stomach and intestinal diseases
- Diseases of the thyroid gland
- elevated blood lipid levels
- hormonal disorders
Noise not only has a physical effect, but also a psychological one, and thus has a lasting negative impact on the quality of life. Possible effects are:
- Decrease in performance & increase in error frequency
- diminished resilience
- Learning difficulties, especially in children
- Nervousness & irritability
- Sleep disorders
Particularly high sound peaks as well as continuous sound damage the human hearing by attacking the so-called hair cells of the inner ear due to noise. The result is persistent limitations of acoustic perception, because these hair cells cannot grow back. Therefore, noise can lead to chronic or temporary ear noises such as tinnitus or even the loss of hearing.
How does noise affect our sleep quality?
During sleep, we go through two sleep stages: the REM ("Rapid Eye Movement") and the non-REM phase. While we do not sleep deeply in the REM phase and our eyes regularly move back and forth, we are in deep sleep in the second phase. In the course of the night, however, the deep sleep phases become shorter and shorter. This means that the phases of light sleep increase. If we are now exposed to an increased noise level, we wake up much faster and more often. Whispering noises of 30 dB are already sufficient for this. If the noise level reaches 40 - 45 dB, i.e. about the level of a conversation at room volume, the body releases more stress hormones. The sleeper does not get any rest. This also impairs performance during the day. It is therefore worthwhile to monitor the noise level in the bedroom and get to the bottom of the causes of poor or restless sleep.
Monitor & evaluate noise exposure
Independent noise measurements are therefore useful. They give you a good impression of the actual noise level in your living environment or at your workplace. Especially long-term measurements allow you to critically question the noise level and your exposure. You can use the air-Q for this purpose. Thanks to the integrated noise sensor, vibrations are continuously detected and recorded. The incoming noise values are output every two seconds as a live value and stored as a 2-min average value. Here, the measuring device offers both an overview of the basic "normal" noise value, where the values are averaged and stored over a period of two minutes, and a noise maximum value. This value shows acute, i.e. short noise events in the historical data, such as a bang - which would not be visible in the noise average value. On the basis of the Noise maximum value, events are documented that can abruptly interrupt rest phases and thus cause stress and sleep problems. In this way, you check both short-term sound levels and longer-term continuous exposure. In the air-Q App you can view the evaluations in detail.
At the same time, the air-Q meets all modern data protection standards: When using an air-Q, no audio recordings are made, as is the case with various smartphone apps for noise measurement. This is because the device only measures the sound pressure.
Equip your air-Q with the noise maximum value by an update
You own an air-Q and want to benefit from the new noise maximum value? Then you only need a software update to add the new function to the already integrated noise sensor. The noise maximum value is then automatically added as a new sensor in the air-Q app. We provide the update for all devices free of charge.
Contributed image: Shutterstock/ Roquillo Tebar
