Subject

Sound is one of the main factors that influence our perception of space. The rapidly increasing rhythms of contemporary urban life have given rise to the remarkable increase of sound pollution. According to former studies, living in an environment with high sound levels may be quite harmful for human beings.

Acoustic problems are usually divided into three main categories:

• Urban Acoustics
• Building Acoustics
• Room Acoustics

Technical solutions for the confrontation of the above problems are already used. The main aim of the present study is to present the possible ecological solutions for the prevention of sound pollution and poor acoustics.

Urban acoustics

The various sounds of an urban environment constitute a sound environment which contributes to the city’s own “character”. A number of these sounds though, are unpleasant and may not be in absolute harmony with the environment.

The decrease of the sound from its sources (road network, airports etc.) might be achieved with the enlargement of the distance between the source and the receiver due to barriers or weather conditions. Reversely the sound can be increased with the phenomenon of reflection. The present study deals with the decrease of sound pollution with the use of noise barriers, which expand in each side of a road network, the prevention of the phenomenon of reflection and the appropriate drawing patterns for the buildings which are near the sound sources.

Noise barriers

Appropriately designed noise barriers constitute an efficient way of preventing road noise, as they hinder the sound emerging from vehicles reach people living near road networks such as motorways, train stations etc. Although noise barriers improve sound pollution, they may cause optical pollution. Therefore both the functional and optical dimensions must be taken into consideration during their designing.

Buildings barriers

Buildings that have no particular demands for a quiet environment such as stores, warehouses and parking spaces can be used as barriers for deterring the sound to reach inhabited areas. Moreover an industrial building with high levels of noise may be parametrically paled by buildings with lower noise levels. The shape of the buildings as well as their placement in relation to the noise are some of the factors that must be taken into consideration in the architectural designing of a building.

Room Acoustics

The main criterion for the classification of a room as having good or poor acoustic is its actual use. When a source of sound is located in a room, sound waves are transmitted throughout the room until the waves reach the walls where a part of the sound energy will be reflected back to the room, a part will be absorbed by the walls and a part of the sound will be dispersed in the wall material. The geometry of the room, the increase or decrease of the sound due to the phenomenon of reflection or the absorption of the materials of which the room is made as well as the time needed for reflection are among the factors which affect the acoustic of the room. The use of echo-absorbing panels which are specially designed to absorb the several sound frequencies might result to the notable decrease of the time needed for echo-reflection as well as to maintain the necessary signal-to-noise ratio so that a further amplification of the sound will not be needed.

Sound-insulation

The sound-insulation concerns the overall ability of a manufacture to prevent the transmission of a sound from one place to another nearby place. There are two types of sound-insulation: Airborne Sound Insulation and Impact Sound Insulation. The most appropriate material for Airborne Sound Insulation is the one with high density and softness. The presence of openings (doors and windows) as well as apertures and ventilators is significant as the sound is transmitted with no remarkable alternation through them. The total sound-reduction of a manufacture usually approaches the sound-reduce of its weakest material. Concerning the second type, Impact Sound Insulation might be achieved by covering the floor with soft material, by placing furred ceiling in the building, by using anti-shocking bases and by constructing a floating slab. Several acoustic materials or a combination of different materials are used for coping with the sounds and vibrations of a construction such as the materials below:

• acoustic furred ceiling, acoustic slates, acoustic wall lagging
• sound-proof and sound absorbing material for roofs, walls, floors etc
• other anti-shocking material