It is a calculation based on the theory and field experience to create an ideal space , like a home theater , karaoke room , separate recordings , meeting rooms and the like , including a place of worship .Measurement of stride frequency and magnitude , can be done with the help of an RTA (Real Time Analyzer ) to know and determine the frequency of reflection or penetrance , so that it can determine the type of material used dampers .
acoustic spaceMany highly effective damping material to be used , for example TraFlex . Have a lot of product variant that allows for making optimal results . Type TraFlex 10:15 , with alpha = 0.7 specifications at 300Hz - 16KHz , very effective if used to make it sound .
1 . preliminaryAcoustic waves are sound waves that can be interpreted by human hearing .A sound wave is a disturbance that is propagated in an elastic medium , which mayform of gas , liquid or solid .
A voice purporting receive vibrations on the ear drum in the area of human hearing frequency . Vibration is produced from a number of variations of air pressure produced by the sound source and propagated into the surrounding medium , which is known as an acoustic field . Variations in atmospheric pressure called sound pressure , in units of Pascals ( Pa ) .Proceedings Semiloka Simulation and Computing Technology and Applications 2005133
A sound source will meradiasikan acoustic sound waves in the field . Acoustic information in the form of sound pressure in the acoustic field can be determined based on the acoustic analysis differensial Helmholtz equation . Calculation of acoustic field like this predicate from the source often disebutsebagai direct problems in acoustics .
The opposite of the direct problem is also important problems in acoustics , in this case the acoustic field is known from measurements can be used to find information on surface acoustic source vibrating .
Problems like this is an inverse problem [ 1-2 ] . Solutions to the direct and inverse problems can not always be obtained analytically ; often confidential problem solving , so the solution is done numerically . Method used forsolve problems on the other boundary element method ( Boundary Element Method) . Profits for this method is a three-dimensional problem is reduced to two dimensions [ 2 ] .
For resources symmetry axis , the surface integral calculation reduced to a line integral . By taking the profit, modeling becomes more modest and only generator should only be purified didiskritisasi [ 3 , 4 , 5 ] . Kim and Ih [ 6 ] using the interior of the NEM to determine the normal velocity and surface pressure on the automotive cabin scale half .
Difficulties that emerged is ill - posed for the inversion process , this is due to the singularity of the transfer matrix . They use regularization to stabilize the reconstruction field . Singular Value decomposition ( SVD ) is used to solve a singular matrix [ 7 ] . Kim and Ih [ 8 ] introduced Tehnik filter for solutions to the problem of ill - posed inverse is common in acoustic radiation .
1 . Basics of Sound1.1 What Is That Noise
Noise is defined as " unwanted sound , such as resisting voices were heard , music , etc., or which cause pain or a lifestyle block . ( JIS Z 8106 [ IEC60050 -801 ] electro- technical vocabulary International Chapter 801 : Akustikal and elektroakustik ) " . Among other environmental pollution , pollution / noise pollution is considered special in this regard :[ 1 ] Evaluation highly personal and subjective evaluation to determine whether to recognize the voice as noise pollution or not , and[ 2] The destruction was localized and sporadic compared to water pollution and air pollution ( Noise aircraft is an exception ) .About characteristics [ 1 ] above , there is a problem about how to put the noise between floors subjective assessment of an individual caught him as " noise " and physical level that can be measured objectively . With characteristic [ 2 ] , there is no clear distinction between who and whom agresornya sacrifice, as so often happens there sacrifices from the noise from the piano and karaoke. Although the number of complaints registered in major cities over the past years has been reduced , the noise is still a big part of the community grievances ( Fig 1-1 ) .Gb . 1-1 complaints - complaints about pollution in Japan by type
Note: Complaints , concerns about soil sediment is removed from the table because it was difficult to describe .Source : Environmental Dispute Coordination Commission
1.2 Three Elements of SoundWhen the keyboard of a piano is pressed , a catch " sharpness " , " high " and "ringing" sound is emitted . This is the state benchmark sensorial quality of the voice and was known as the "three elements of voice " .As the physical size of the " loudness " , is the amplitude and sound pressure level. For " high " voice is frekwensi . About the tone, there is a large amount of physical size , the tendency now is combine all the period that is the nature of the voice , including height , sharpness and spectral distribution as "ringing" .
1.3 Frekwensi and WavelengthThink for a moment about the particles from the air which made. Where the particles are dense , the air pressure increases, in which the particles are rare, the pressure decreases . Symptoms that are transmitted by the pressure change is referred to as sound waves . A transmitting sound waves to the speed of sound with a wave-like motion . The distance between two geographic points ( ie two points between which the maximum sound pressure of a pure sound produced ) are separated only by a period and showing the same tone named " Soundwave " , which is expressed as ( m ) . Then , when the sound pressure at an arbitrary point change periodically , the total number of times in which these periodic fluctuations repeated in a second named " frekwensi " , which is expressed as f ( Hz , see Fig. 1-2 ) . Voices are air- frekwensi high voice , whereas the air- frekwensi low is low voice . The relationship between the speed of sound c ( m / s ) , wave and frekwensi f is expressed as follows:c = f xThe wavelength of a sound that can be heard is a few centimeters and about 20 m . Most of the objects in the environment we have in this sphere . Sound quality , which is influenced by roughly surfaces that reflect sound , high fences and other factors , will vary as a comparison of the wavelength of the object dimensions , as the problem becomes more complicated .Gb . 1-2 Gb sinusoidal wave . Contour 1-3 pitch
1.4 outline the loudnessIt is said that the difference threshold voice could be heard by the average person is 20 to 20.000 Hz, but can depend on the frekwensi heard of him . The tests ( hearing ) psychiatric produce lines of loudness as it is shown in Fig . 1-3 . Curve using 1000 Hz and 40 dB as a reference for pure sound and effect sound this reference plot with the upper floors could be heard from the same loudness at various frekwensi .As shown in the picture , the loudness of voice received by the human ear vary due to two physical properties that is the sound pressure level and frekwensi . Even within the scope of that could be heard , frekwensi low - and high frekwensi difficult to catch. It is a high sensitivity in the scope of 1-5 kHz.When the loudness level of a sound is reduced , at a certain point , the sound is no longer heard . These levels also vary according to frekwensi . These levels are indicated as the minimum level that can be heard ( dotted line ) in Fig . 1-3 . Minimum level that can be heard at 20 dB or more is viewed as hearing difficulties .
1.5 Effect / Consequences of NoiseAccording to definition 1.1 noise , when a voice interrupt the person who is reading or listening to music , so the voice is that despite the noise of other people may not be bothered by the noise . Although the influence of voice has much to do with psychological factors and emotional , some cases where serious consequences such as loss of hearing occurs because the high level of voice loudness in a weighted sound pressure level or ear permanently installed because the noise
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