Auralisation – Wikipedia
Auralisation (“Disturbance” by lat. auris = dt. ‘Ohr’ = auricular) is a procedure for the artificial audit of an acoustic situation. In space acoustics, z. B. using the simulation of mirror sound sources, ray tracing and the calculation of the diffuser sound enables a room to be heard, taking into account its geometric and acoustic properties. Also the word Peralization is sometimes used for it.
Model measuring methods have been common in acoustic construction since the early 1950s. The acoustic situation of the planned space is measured on a model made of wood, plaster and plexiglass, mostly in a scale of 1:20. However, this procedure represents an enormous time and financial effort.
The auralization was developed at the end of the 1960s and brought several advantages over the model measurement method.
In the past ten years, the auralization process has experienced a strong further development that is directly linked to the ever higher computing power of modern computers.
- Room acoustics
Auralization gives the acoustician new opportunities to draw precise conclusions about the effects of its measures in the planning phase and also to assess them by listening. Another use of auralization that should not be underestimated is your use to present acoustic planning. Similar to a three -dimensional, virtually walk -in space model, the architect enables its customers to present the planned premises, the acoustician now has an equivalent presentation option with the help of auralization. He can let the customer hear how his premises will sound, and in this way he clearly demonstrated the benefits of his measures. With conventional means, on the other hand, it is much more complicated to make it clear to an acoustic layperson how important planning the sound is in one room.
- Electroacoustic
Interactions of sound source (quantity, position, radiation characteristics, amplitudes, etc.) and room acoustics can be tested against each other and the results can be used as a basis for making a sound system.
- Baukustik
In construction acoustics, auralization programs serve primarily to evaluate soundproofing properties of components. The absorption levels and the acoustic behavior of soundproof doors or windows can be tested using virtual models.
- Ambient noise
Auralization is used to evaluate the influence of ambient noise, such as the noise of roads, railways, air traffic, wind farms, etc.
- Vehicle acoustics
Auralization is a tool for evaluating acoustic measures in vehicle construction, both in relation to the situation in the passenger cell and the insulation of the interior.
- Folding hall
The most exotic “application” of auralization, the folding hall, has emerged from a sound motivation. In principle, however, these programs work, such as Emagic’s Space Designer , On the same principle as auralization programs: on the folding of audio material with a space pulse response. One of the oldest folding hall plugins is that Acoustic Modeler (DirectX), which has been on the market since 1997.
The principle of auralization in spatial acoustics can be described as follows:
input [ Edit | Edit the source text ]
When entering, information about the following crucial factors must be taken into account:
- Type of sound source and receiver
- Position and possible movement of the source and the recipient
- Transfer routes to be taken into account
- Space influences: size, shape and degree of absorption (α; in the terz or octave band) and scattered levels of all areas and objects.
This input can be done in most programs both in a text editor and in a graphics editor.
The first step is the geometric input of the room. All points of the room must be defined in a coordinate system.
Then you define all boundaries via their cornerstones. Acoustic properties are then assigned to these areas, i.e. H. their absorption levels in Terz or octave bands. Finally, the position and the type of sound source or recipient are entered.
Example: Source text extract from a project with the software Catt-Acoustic v.8 :
Source: Explanation:
CORNERS 201 0 0 0 Definition of the four points of the 202 -W 0 0 In the illustration (above, "model 203 -w d 0 of an auralized space ") brown 204 0 d 0 shown area.
PLANES Definition of area 1 called [1 floor 201 202 203 204 CARPET_SOFT ] “Floor” between the 4 points. Assignment of absorption behavior called "Carpet_soft"
ABS CARPET_SOFT = Definition of absorption behavior <7 8 21 26 27 37 47 57> Absorption degree in percent per octave band 125Hz 250Hz 500Hz 1kHz 2kHz 4kHz 8kHz 16kHz {191 168 155} Definition of a color to represent
calculation [ Edit | Edit the source text ]
In the second step, the program using three essential procedures is a synthetic Spatial pulse response calculated:
- the Simulation of mirror sound sources
- the so-called Raytracing
- the Calculation of the diffuse sound
With the mirror sound source method, the positions are
the mirror sources “behind” determine the boundary areas, which then all at the same time
send an impulse. Depending on the distance to the recipient and the absorption levels of the areas, the early reflections can be calculated.
However, this procedure is almost exclusively limited to cuboid rooms.
In the case of raytracing, the sound source sends a large number of rays (10,000 to 80,000 per octave) and followed their path to the recipient. Raytracing can provide information about the hall flag of a room, or complete the reflectogram. However, it is not suitable for real -dietaryization, since it is connected to a computing effort in the area of hours.
In the case of the diffuse sound calculation, the reverberation is calculated based on sizes and contexts known from measurements. This happens using filtered, exponentially cozy noise.
Depending on the respective software, the methods mentioned above are used individually or in combination.
output [ Edit | Edit the source text ]
In the end, any sound recording with the acoustic properties can
of a room ( Spatial pulse response ) and the outer ear transmission function. The
Outdoor ear transmission function is used to simulate angle -dependent transmission functions of the human ear and is essential for the natural reproduction of the material.
The resulting binaural signal can then be presented and assessed via headphones.
Common auralization programs are:
- Room acoustics
- CATT-Acoustic
- EASE
- Aqua (mirror source simulation)
- Auvis
- ODEON (Raytracing)
- Ulysses
- Baukustik
- SONarchitect ISO
- BASTIAN
- NORA
- NOISE REDUCTION Auralization (real -dietaryization system)
- Neglect the shaft native of the sound
Auralization programs are based on a geometric view of acoustics. They all neglect the wave native of the sound. This means that all signs of flexion are not recorded. For the above reason, geometric room acoustics have no general validity in small rooms. In large rooms, auralization processes can deliver acceptable results almost over the entire frequency range. In contrast, the deep frequent area of the spectrum must not be included in small rooms. “Large” or “small” refers to the wavelength here l .
- High computing effort
Reflections of higher order can lead to high arithmetic, especially when raytracing. This can be partly in the range of several hours. In order to shorten the computing time, the procedure is often canceled prematurely and the space impulse response is supplemented with statistical abrasion times, which leads to inaccurate results. The ray tracing process for modern GPU has recently been optimized, which leads to an exponential increase in performance. [first] This further development has so far referred to applications in image synthesis; In principle, transmission to applications in auralization is possible and the high computing effort is null and void as a counterpoint.
- Simplification of the models
Due to the high expenditure of time when entering the geometric structures, the room models are often simplified. This clearly leads to falsifications of the result.
- 16 Bit PC sound cards
The dynamics are limited to 96 dB by 16 bits. There is also a high self-noise of the PC sound cards. Therefore, very quiet or very loud results cannot be presented adequately.
- Psychoakustik
Signals that are too short (15 to 20 s) are not sufficient to be able to assess their effects, especially in cases of noise pollution. Furthermore, reinforcement of the signal is possible. As a result, signal components that are actually not audible are raised over the hearing threshold, which falsifies the impression of the listener.
- General
- Michael Vorländer: Auralization – Fundamentals of Acoustics, Modelling, Simulation, Algorithms and Acoustic Virtual Reality Springer, Berlin 2008, ISBN 978-3-540-48829-3.
- Michael Dickreiter: Handbook of recording studio technology: room acoustics, sound sources, sound perception, sound converter, sound engineering, recording technology, sound design. 6. Edition. 2 volumes. Saur, Munich 1997, ISBN 3-598-11321-8.
- Friedrich u. a.: Table book Information and Communication Technology. 8. Edition. 1997.
- Acoustic
- W. Fasold, E. Veres: Sound insulation and space acoustics in practice. 2nd Edition. Huss media, 2003.
- Auralisation
- M. Vorländer, R. Thaden: Auralisation of Airborne Sound Insulation in Buildings. In: Acustica / Acoustica. Band 86, nr. 1, 2000, S. 70-76.
- M. Vorländer, R. Thaden: Disturbance of soundproofing in buildings. In: Magazine for noise control. Band 47, 2000, S. 169–173.
- M. Vorländer, H. A. Metzen: Auralization – a new tool for building acoustic planning. In: German architect sheet. Band 5, Nr. 1, 2001, S. 61ff.
- M. Vorländer: Auralization in Noise Control. Plenary lecture, Proc. Inter-Noise ’03, Jeju, Korea, August 2003.
- N. Question: Computer Modelling and Auralisation of Sound Fields in Rooms – An Overview. Invited paper for ICA, Kyoto/Japan 2004.
- A. Freuden shot: Construction and space acoustics using the example of the radio studio of the Deutsche Welle Berlin. Specialist work on the Sae-München, 2004.
- M. Vorländer: Room Acoustics in Virtual Reality. Plenary lecture, International Symposium on room acoustics – ISRA. Sevilla, September 2007.
- ↑ For example described here: http://graphics.stanford.edu/papers/i3dkdtree/gpu-kd-i3d.pdf
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