3-mimaride akustik - açık kapalı mekan

8/7/2019 3-Mimaride Akustik - Ak kapal mekan

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Architectural Technology VArchitectural Acoustics


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Part 3

Contents

Direct and reflected sound (dolaysz ve yansyan ses)

Reverberant sound (yansm ses)

Reverberation time (yansm sresi)

Distorsion (distorsiyon)

Masking effect (maskeleme etkisi)

Early First-Reflected Sound (erken ilk yansmalar)

Echo (yank) Flutter echo (rpntl yank)

Focusing (odaklanma)


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Direct and reflected sound

(Dolaysz ve yansyan ses)

The sound in a certain listeningpoint in a room is composed ofthe direct sound and the

reflected sound. The directsound is the sound that has notyet been reflected in a surface.

Hacmin bir dinleyici noktasnda alglanan ses dolayszve yansm seslerden oluur. Dolaysz ses kaynaktankp hibir yzeyden yansmadan direkt dinleyiciyeulaan sestir.


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Reverberant sound

(Yansm ses)

First-Early reflections(lk yansmalar)

The sum of all reflected soundis called the reverberent soundfield. It consists of all sound thathas been reflected once, twiceor more in the buildingconstruction surfaces. The

sound reflected one time iscalled 1st reflections, two times2nd reflections etc.

Hacimdeki tm yansyansesler yansm sesioluturur. Bu sesler hacimyzeylerinden 1, 2 ya da dahafazla kez yansyan seslerikapsar. Hacim yzeylerinden1 ya da 2 kez yansyarakdinleyiciye ulaan seslere ilkyansmalar denir.


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The number of reflectionsaffecting the reverberantsound field depends onthe acoustic properties ofthe surfaces. If the

building surfaces weretotally sound reflecting,there would theoreticallybe an infinite number ofreflections. If the surfaceswere perfectly absorptive,

there would be noreflections at all. In reality,there is always a loss ofenergy when a soundwave hits a wall.

Hacimdeki yanstc

yzey miktar yansyanses alann etkiler. Hacimyzeyleri ne kadar

yanstc ise yansm

ses oranda fazla olur.


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Two-dimensional sound reflections in a room with only

reflecting surfaces.

Sadece yanstc yzeylerin bulunduu bir hacimdekiyansmalar


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Two-dimensional sound reflections in a room with oneabsorbing surface.

Ses yutucu yzeylerin de bulunduu bir hacimdekiyansmalar


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Air absortion (Havann yutuculuu)

The air also absorbs some of the sound wave's

energy. The sound absorption is frequency

dependent . High frequency sound is often moreeasily absorbed than low frequency sound.

Hacmin iini dolduran havann da sesi yutmazellii vardr. Hava zellikle ince seslerikaydadeer miktarlarda yutar.


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Reverberation Time

(Yansm sresi-RT)

The reverberant sound in an auditorium dies away with

time as the sound energy is absorbed by multiple

interactions with the surfaces of the room.

Hacmin iindekiyansm ses enerjisi

yzeylerin yutuculuuna

bal olarak zaman iinde

giderek azalr.


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In a more reflective room, it will take longer for the sound

to die away and the room is said to be 'live'. Yanstcl fazla olan bir hacimde yansm ses

enerjisindeki bu azalma daha uzun srede gerekleir ve

bu hacimler canl olarak adlandrlr.


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In a very absorbent room, the sound will die awayquickly and the room will be described as acoustically'dead'.

Yutuculuu fazla olan hacimlerde ise yansm ses

enerjisindeki azalma daha ksa srede gerekleir ve buhacimler l olarak adlandrlr.


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Example of decrease corresponding to a RT60 of 1,8s :


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Calculating Reverberation Time

(Yansm sresi hesab) When expressed in units of cubic and square meters, the

reverberation time is given by

(m3 ve m2 cinsinden yansm sresi aadaki formllerhesaplanr)

RT = 0.16 V/A,

where V is the volume of the room and A is the effective ``totalabsorption'' area. (The ``total absorption'' area is calculated as thesum of all surface areas in the room, each multiplied by its

respective absorption coefficient.) (Formlde V hacmin bykl, A toplam yutuculuktur. Toplam

yutuculuk hacim yzeylerinin byklk ve yutuculuklarna balolarak belirlenir)


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Optimum Reverberation Time(Optimum yansm sresi)

Optimum reverberation times at 1kHz for a number of different roomsizes and uses.

1000Hz(1 kHz) iin farkl byklk ve fonksiyonlardaki hacimler iinoptimum yansm sreleri.


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Optimum Reverberation Time

In general bigger spaces will have longer reverberation times than smaller spaces.

Ayn fonksiyon iin hacim bykl arttka optimum yansm sresi de uzar.


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Distortion(Distorsiyon)

The reverberation times of aroom must be calculated in allfrequencies (at least for 6octave band). If thereverberation times differ forthe frequencies, it caused adistorsion. In this case it canbe heart a distortion for theoriginal characteristics of thesound.

Bir hacmin yansm sresi en az 6 frekans iinhesaplanmaldr. Eer yansm sresi frekanslara grefarkllk gsterirse distorsiyon oluabilir. Distorsiyon sesinkarakteristiini bozan bir akustik kusurdur.


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Masking effect (Maskeleme)

In a room with the highreflective surfaces, highreverberation accures.High reverberation abovethe optimum levels may

cause masking effect.This case effects theintellibility of speech.

Bir hacimde yutuculuu yksek yzeyler uzun yansm

srelerinin olumasna neden olurlar. Optimumdeerlerin zerindeki uzun yansm sresi maskelemeyeneden olur. Bu durum konumann anlalabilirliiniolumsuz ynde etkiler.


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Masking effect for fast tempo for Long andShortreverberation time (Hzl tempolu seslerde maskelemeetkisi)

Masking effect for slow tempo (yava tempolu seslerde

maskeleme etkisi)


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Frequency plays a part: a louder sound heard at onefrequency prevents softer sounds near that frequencyfrom being heard. However, not all frequencies mask the

same. Mid-band frequencies mask far better than lowfrequencies.

Dzeyi fazla olan ses dzeyi az olan sesi maskeler,bunun yansra frekanslarn maskeleme etkileribirbirinden farkllk gsterir. Orta frekanslar ve dkfrekanslarn maskeleme etkisi daha fazladr.


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Early First-Reflected Sound

A large difference between the time of arrival of the direct sound andthe first reflected sound is perceived by the listener as a sense ofisolation from the performance. Terms used are that theperformance lacks presence and "intimacy".

Dolaysz ses ve ilk yansmalar arasndaki ulam sresi farknemlidir. Bu sre farknn ok uzun olmas kaynan yerininalglanmas asndan problem oluturur.


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Echo (Yank)

Reflection of sound waves canlead to one of two phenomenon -an echo or a reverberation. Areverberation often occurs in asmall room with height, width, and

length dimensions ofapproximately 17 meters or less.

Yansyan sesler yank ve yansm olarak iki akustik oluuma

neden olabilir. En, boy ve ykseklik boyutlar 17 metredenkk olan hacimlerde yansmalarn tm yansm oluturur.


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In the case of the balcony face, this problem can be

overcome by careful design of the face to control the

reflection. Covering the surface by absorbent materials is

another solution.

Balkon bulunan salonlarda balkon korkuluundanyansyan ses nlar yank oluturabilirler. Bu nedenle

yank oluturabilecek yzeylerin ses yutucu elemanlarla

kaplanmas yararl olur.


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Diffusers at the rear wall for avoiding echodisturbance.

Yank oluturan yzeylerin ses datc(yayc)

malzemelerle de kaplanmas yararldr.


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Flutter echo (rpntl yank)

Probably the most common andimmediately noticeable room problemresults from having parallel surfaces

(walls, floor and ceiling) with a hardfinish that reflects sound. Theresulting effect is called flutter echo.

rpntl yank, paralel ve yanstcyzeyleri olan mekanlarda grlen bir

akustik problemdir.


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To treat flutter echo you need tocontrol the reflections on one or bothof the parallel surfaces. This usuallymeans applying some sort of sound-absorbing or sound-diffusing material

to the side walls between thespeakers and your listening position.Carpeting or acoustic ceiling tile willreduce floor/ceiling flutter echo.

Paralel yzeyleri yutucu ya da datcmalzemelerle kaplamak ya daduvarlarn paralelliini bozmak buakustik problemi ortadan kaldrabilir.


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Focusing (Odaklanma)

Some surfaces can 'focus' sound (e.g.parabolic reflector).

bkey yzeylerde yansyan seslerhacmin belli bir noktasnda odaklanr.


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One method for overcomingfocused reflections fromparabolic rear wall is to serratethe rear wall.

Odaklanmay nlemeninyntemleri odaklanma oluanyzeyi yutucu yapmak, datc

yapmak ya da girinti kntlyapmaktr.

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