Basic information about noise

Noise is considered to be a sound that is perceived to be unpleasant. The sound level is measured in decibel (dB). The frequency of sound is measured in Herz (Hz). The Hertz describes how low or high the sound is, while the decibel describes how loud the sound is. A three-decibel change is a change perceptible to human ears, and a 10-decibel change represents a doubling of the volume of the sound heard. High- and mid-frequency sounds are often perceived as more annoying than low-frequency sounds.

Continuous noise exposure can cause health effects: this is why it is to be avoided. Health effects include, for example, increased stress and sleep disturbance.

Noise can be persistent or temporary. Persistent noise is, for example, road traffic noise, while temporary noise is generated, for example, at construction sites.

Structure-borne noise is caused by the vibration of structures. Vibration caused by traffic, for example, can be transmitted through the ground to the structure of a building, causing it to vibrate loudly. Vibration is also transmitted in the structures, but it is a low-frequency sensory vibration. In cities, vibrations and noise are mainly caused by rail traffic. Inside a house, vibrations and structure-borne noise can be caused by, for example, piping or technical equipment.

The perception of a sound as annoying, or noise, is individual. Therefore, the health effects of noise can also depend on how annoying the noise is perceived. However, this only applies to relatively low noise levels, as high noise levels pose a health risk regardless of how the noise source is perceived.

Noise exposure can reduce comfort. Health problems caused by noise include sleep disturbance, memory and performance deficiencies, and hypertension. In addition, annoying noise can increase stress, which, if it continues, can exacerbate the above symptoms.

Sleep disturbance can manifest in many ways. A noisy environment can make it difficult to fall asleep, reduce the quality of sleep or wake you up in the middle of your sleep. Sleep deprivation is a health hazard that can exacerbate other health hazards. Memory and performance deficiencies due to noise are often shorter in duration than sleep disturbances. When the noise stops, memory and performance are restored to a normal level quite quickly.

Interior noise is regulated by the Housing Health Decree, the application guidelines(external link, opens in a new window) of which provide more detailed information on the noise measurements and action thresholds. They provide noise levels that should not be exceeded. According to the action thresholds, the average indoor sound level must not exceed 35 dB during the day between 7:00 and 22:00 or 30 dB during the night between 22:00 and 7:00. Interior noise is measured with the windows and doors closed. Noise level is calculated as average sound level, because of which the sound levels can momentary be higher than those mentioned above.

Government Decision 993/1992(external link, opens in a new window) governing the planning of and permits for land use, traffic, and construction lays down guideline values for example in outdoor areas. As a rule, new sites are planned and permits granted so that these guideline values are not exceeded. For previously built sites, exceeding the limit values does not always necessitate actions.

A noise area is an area where the noise guideline values are exceeded. In land-use planning, noise areas are taken into account so that noise abatement in their area must be considered with particular care.

The definition of a quiet area varies slightly depending on whether EU or national guideline values are applied. In the context of the noise abatement action plan required by the Environmental Noise Directive, a quiet area is defined as an area with an average sound level of less than 50 dB by day and less than 45 dB by night. According to the national definition, the average noise level in a quiet area is less than 55 dB by day and less than 50 dB by night.

Quiet areas are important for the recreation of the residents. However, from the point of view of recreation, the noise level itself is not necessarily the most important factor: landscapes and nature experiences, for example, can be more important in this respect. Also, although the noise level may be high in spring, for example, at the beginning of the bird nesting season, bird singing is often perceived as pleasant despite its high sound level.

Noise is measured as average sound level, meaning the average volume of the sound between, for example, 7:00 and 22:00. Indoor noise must be measured with the doors and windows closed. Noise measurement is always carried out by professionals. The aim is to determine whether the noise action thresholds in accordance with the Housing Health Decree are exceeded in living quarters. Indoor noise measurements are used to determine noise other than that caused by road traffic. Noise from other parts of the building, caused by ventilation equipment or the like, can constitute a reason to measure noise indoors.

In addition to measuring, the sound level can also be modelled. Noise modelling is based on knowing how much noise is caused by, for example, a certain amount of vehicle traffic. The noise situation in the area near the road can then be modelled, taking into account the shapes of the terrain, placement of buildings and any noise barriers in relation to the noise source, for example. Noise modelling is the most common way of assessing noise in connection with new planning projects. They have, among other things, the advantage that they are not weather-dependent and allow to assess the noise situation even if the noise source does not yet exist. Modelling can also be used to assess the development of the noise situation with respect to the impact of changes in traffic volumes and any planned buildings on the intensity and propagation of noise.