Suspended ceilings constructions can improve the sound insulation of air and impact noise in civil buildings. To minimize the volume of the room, two types of suspended acoustic ceilings are most often used. They are: with the attachment of the structural shell of the ceiling close to the floor slab, and at a low suspension height. The influence of the slab's surface density on the correction to the sound insulation, which is created by the suspended ceiling, both in the first and in the second type, is considered. A method for a correction calculation for the sound insulation due to a suspended ceiling in these cases is given. At a minimum height the method is based on taking into account acoustic power's radiation coefficient of the shell. While for the low suspension height the method deals with the vibration's transmission from the floor slab to the ceiling's shell through the air layer and through the metal fasteners, that in this case become acoustic bridges. As a result, the formula of frequency response for sound pressure lowering, due to the sustained ceiling structure, is obtained. The influence of plasterboard suspended ceiling's perforation on the sound insulation of the entire floor structure is evaluated.

Keywords: suspended ceiling, impact noise isolation, airborne noise isolation, acoustic radiation power, limit frequency, acoustic bridge, acoustic impedance, vibration velocity level, porous and fibrous material, perforated plasterboard

The article discusses the dynamic characteristics of mineral wool materials (dynamic modulus of elasticity and stiffness, reduced dynamic stiffness) and the effect on them of porosity and relative deformation of the material. The main objective of the study is to determine the value of the dynamic modulus of elasticity, taking into account its change with time under the action of a long-term static load for calculating the impact noise insulation.

Keywords: mineral wool material, dynamic modulus of elasticity, strength of parts of a structure, sound insulation, ultimate states, construction

Creating a comfortable acoustic climate and an enabling environment for listening to music and speech is crucial in the acoustic design of home theatres. The main requirements for the acoustics of home theater halls are low background noise, diffuse sound field, no echo and optimal reverberation time. The reverberation time is calculated in a certain order. The acoustic mode of the home theater room is assessed in the process of acoustic design.Then the acoustic cladding and electroacoustic equipment are selected. The acoustic system and loudspeakers of a certain orientation are selected depending on the size of the room and the frequency of sound reproduction.

Keywords: acoustics, sound, sound field, home theater, reverberation time, sound absorption coefficient, sound absorption area, acoustic systems, loudspeakers

The factors having impact on profitability of enterprise structures are presented in article. The directions of increase of competitiveness of enterprise structures are presented

Keywords: business, businessman, profitability, efficiency, productivity, enterprise structures