2-mimaride akustik - akustik malzeme

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Architectural TechnologyArchitectural Acoustics

Part 2 Contents

Auditorium acoustics (Hacim akusti i) Sound propagation (Sesin yay lmas ) Outdoor- ndoor sound propagation (i ve d mekanlarda grlt yay l m ) Reflection-absorbtion-diffusion (yans ma-yutulmada lma) Porous materials (gzenekli gereler) Panel absorbers (titre en levhalar) Resonators (rezonatrler) Diffusion of sound (sesin da l m )

Auditorium Acoustics The room in which we listen to sounds has an important influence on what we hear. Auditorium acoustics will identify some of the principal means currently available for judging the quality of an auditorium. However, the design of such spaces is still considered an inexact science.

Hacim akusti i, hacim iindeki ses kayna ndan kan seslerin, tm dinleyicilerin kulaklar na en iyi ko ullarda ula mas n sa lamaya al an akustik dal d r

Hacim akusti inde nemli olan konular

Ses kalitesinin sa lanmas Konu ma ve mzi in anla labilirli i Hacim iinde kullan lan yzey malzemelerinin akustik zellikleri ve yerleri Hacim iindeki tm noktalarda sa lanm olmas gereken yeterli ses dzeyi

Sound Propagation (Sesin yay lmas )Sound Propagation Outdoors (Sesin a khavada yay lmas )

Before starting to look at sound propagation indoors, let us study how sound behaves outdoors, under free field conditions.

Sound waves emitted from a point source propagate spherically equally in all directions from the source. (A k havada bir kaynaktan kan ses kresel dalgalar biiminde yay l r.)

At a distance from the source, the same energy is distributed over a sphere. The greater the distance from the source, the larger the surface over which the energy is dispersed. This may be illustrated by studying a segment of the expanding sphere.

Kaynaktan kan sesin dzeyi, uzakl orant l olarak azal r.

n karesi ile

The sound energy is dispersed over an imaginary sphere with a surface that grows in proportion to the square of the distance from a point source.

The surface of the sphere grows 4 times with each doubling of the distance from the source. The sound hence rapidly declines with the distance from the source. Each doubling of the distance from the point source yields a 6 dB reduction of the sound level.

Nokta kaynaklardan yay lan kresel ses dalgalar n n bykl uzakl n her iki kat na kmas yla 4 kat byr. Bu da nokta kaynaktan her iki kat uza a gidildi inde ses dzeyinin 6 dB azalmas na neden olur.

Outdoor sound level calculation: A k havada ses dzeyi

I = W / 4 r2 (dB)W = Source power (Kaynak gc) (watt or watt) r = source-receiver distance (kaynak-al c uzakl ) (m or cm)

Sound Propagation Indoors (Kapal hacimde sesin yay l ) The sound propagation in rooms is different from the sound propagation in free field. Sound in rooms is reflected from hard surfaces and influence the room acoustics. Kapal mekanlarda sesin yay l a k havaya gre farkl l k gsterir. Kaynaktan kan ses nlar hacim yzeylerinde ok kereler yans rlar.

Indoors, the sound wave hits building construction surfaces before it is significantly attenuated. The sound field indoors is not spherical but depends on the geometry and the acoustical properties of these surfaces. The volume of the room and the distances between the sound source, the building construction surfaces and the listening point are also important.

Kapal bir hacimde, kaynaktan kan ses nlar , hacim i yzeylerinde pek ok say da yans ma yaparak btn hacme yay l r. Bu gibi ortamlarda olu an ses alan na, yay n k ses alan ad verilir.

Reflection Absorption Transmission - Diffusion

When sound energy falls on the boundary of an enclosure, such as a wall or a ceiling, part of the energy is reflected back into the enclosure, a part is absorbed within the material of the boundary and converted into heat, and a part is transmitted throught the boundary element. Ses n hacmin i yzeylerinden duvar ya da tavan gibi bir yzey zerine geldi inde, yans yarak tekrar hacme geri dnebilir, bir blm yzey taraf ndan yutularak s enerjiine dn ebilir, bir blm de arka hacme geebilir.

SOUND ABSORPTION

All materials have some sound absorbing properties. Incident sound energy which is not absorbed must be reflected, transmitted or dissipated.

Sound absorption is defined, as the incident sound that strikes a material that is not reflected back. An open window is an excellent absorber since the sounds passing through the open window are not reflected back but makes a poor sound barrier. Painted concrete block is a good sound barrier but will reflect about 97% if the incident sound striking it. Yutulan ses yzeye giden ancak hacme geri yans mayan ses olarak tan mlan r. rne in a k bir pencereye giden sesin tm yutulmu kabul edilebilir ve geri yans maz. Boyal beton blok yzey ise %97 yans t c l kta olabilir. Bu da yzeyin yutuculu unun %3 oldu u anlam na gelir.

A materials sound absorbing properties can be described as a sound absorption coefficient (a or ) in a particular frequency range. The coefficient can be viewed as a percentage of sound being absorbed, where 1.00 is complete absorption (100%) and 0.01 is minimal (1%). Bir yzeyin yutuculuk zelli i yutma arpan (a ya da ) ile tan mlan r.%100 yutuculuktaki bir hacmin yutma arpan 1, %1 yutuculuktaki bir hacmin yutma arpan %0.01dir.

BASIC CATEGORIES OF SOUND ABSORBERS (Ses yutucu malzemeler) There are three basic categories of sound absorbers: (Ses yutucu trleri)

Porous materials commonly formed of matted or spun fibers; panel (membrane) absorbers having an impervious surface mounted over an airspace; and resonators created by holes or slots connected to an enclosed volume of trapped air. The absorptivity of each type of sound absorber is dramatically (in some cases) influenced by the mounting method employed.

Porous materials (Gzenekli gereler)

Common porous absorbers include carpet, draperies, spray-applied cellulose, aerated plaster, fibrous mineral wool and glass fiber, open-cell foam, and felted or cast porous ceiling tile. Generally, all of these materials allow air to flow into a cellular structure where sound energy is converted to heat. Porous absorbers are the most commonly used sound absorbing materials Porous materials are usually most efficient at absorbing high frequencies.. Gzenekli gereler iinde pek ok say da k lcal borular, delikler ya da ok ince aral klar bulunan ve bundan tr olduka hafif olan organik ya da inorganik gerelerdir. Bu k lcal borular ya da aral klar d havaya a kt rlar ve hava ile doludurlar.

Porous materials (Gzenekli gereler) Gzenekli gereler, perde ve hal gibi baz zel kullan lar d nda mimari mekanlar n i yzeylerinin kaplanmas nda kullan lmaya her zaman elveri li de illerdir. Genellikle, yumu ak ve a nmaya dayan ks z olduklar ndan zellikle duvar kaplamas olarak kullan labilmeleri, delikli levhalar, kafesler ve benzeri koruyucular n arkas na yerle tirmek gibi baz tedbirlerin al nmas na ba l d r.

Bu durumda, yaln zca ndeki koruyucunun bo luklar ndan geen ses erkesinin gzenekli gerece ula abilmesini ve belli oranda yutulabilece ini unutmamak gerekir.

Kullan ld klar yerler

Ayr ca, yap bnyesinde gzenekli gere zelli i gsteren ta yn ve cam yn esasl malzemelerin kullan m da yayg nd r. Bu gereler, koruyucu elemanlar ile birlikte yap yzlerinde kullan labildi i gibi,

Kullan ld klar yerler

kaplama levhalar n n arka yzlerinde ve sandvi sistem blme elemanlar nda grlt denetimine ynelik olarak uygulan rlar.

Zaman ve dayan kl l k

Bir ba ka nemli nokta da, gzenekli yapma tavan levhalar ve genellikle gzenekli gerelerin, badana, boya, cila ve benzeri uygulamalarla gzeneklerinin d havaya a k ular n n t kanmas d r. Byle bir durumda, gzenekli gerecin bir anlam n n kalmayaca a kt r. Ayr ca, gzenekli gerelerin akustikle ilgili de i ik kullan l lar nda, bunlar n bas n alt nda s k arak, rutubetlenerek, slanarak ya da benzeri ekillerde gzeneklilik zelliklerini yitirmemelerine dikkat etmek gerekir.

Malzemenin kal nl gzenekli gerecin yutuculu unu artt r r ve daha geni frekans alan nda sesi yutmas n sa lar.

The thichness and absorbtion coeffifient of the felt

2) Panel Absorbers:

Typically, panel absorbers are non-rigid, non-porous materials which are placed over an airspace that vibrates in a flexural mode in response to sound pressure exerted by adjacent air molecules. Common panel (membrane) absorbers include thin wood paneling over framing, lightweight impervious ceilings and floors, glazing and other large surfaces capable of resonating in response to sound. Panel absorbers are usually most efficient at absorbing low frequencies.

Ses enerjisinin bir levhay titre tirmesiyle bir i yapt yani belli bir oranda sarfedildi i d nlebilir. Bir levhay titre tiren ses enerjisi, levhan n tesbit yerlerindeki srtnmeler, levhan n ekil de i tirmesiyle ilgili i srtnmeler, levhan n arkas nda bulunan hava tabakas yla ilgili srtnmeler ve benzeri ile sonunda s enerjisine dn r.

Titre en levhalar, btn benzer sistemlerde oldu u gibi, z frekanslar na yak n frekanslardaki sesleri en byk oranlarda yutarlar. Titre in levhalar, boyutlar ve gere cinsleri bak m ndan, z frekanslar olduka alak frekanslarda olan paralard r. Bu nedenle titre en levha zelli i gsteren gereler kal n sesleri ince seslerden ok daha fazla yutarlar.

Titre en levhalara rnekler

Yap larda mimari yap msal paralar olarak kullan lan titre in levha zelli i gsteren elemanlar; lambriler, tavan kaplama levhalar , kiri lemeli esnek d emeler, ba dadi zemine s va, pencere camlar , e itli panolar vb)

De i ik kesit zellikleri bulunan titre en levha zelli i gsteren gereler ve frekanslara gre de i en yutma arpanlar

Bir levhan n titre ebilmesi

Bir levhan n fazla ses yutabilmesi iin, kolay titre ime girebilmesi g