Acoustic analysis
In today’s world, where sound plays an important role in all areas of life – from music to communication technologies – acoustic analysis is becoming an extremely important tool. In this article, we will delve deeper into the importance and applications of acoustic analysis, discovering how this technology contributes to a better understanding of sound in a variety of contexts, from medicine to audio engineering.
Introduction to acoustic analysis
The concept of acoustic analysis does not have a single, fixed definition. Simply put, acoustic analysis is the interpretation of results and searching for relationships between the parameters of the tested object based on the measurements performed.
Typically, such an analysis consists of several parts or stages:
The first part is a report with the results of tests carried out on the facility, where specific acoustic parameters are available. An example would be a report showing noise at a machine workstation. Typically, such a report consists of an answer to the question whether the noise exceeds the permissible standards specified by law or as specified by the designer.
The actual part of the acoustic analysis, i.e. the second part, answers the questions why the standard was exceeded and what actions should be considered to effectively reduce the noise emission level.
In this step may be to create an acoustic model, which is a kind of acoustic simulation of the examined space. Specialized software is used for this purpose and allows you to analyze all solutions (you can check whether inserting or thickening existing walls or screens will affect the noise emission level, etc.).
Building an acoustic model is a very convenient and effective tool for advanced acoustic analysis.
Basic concepts related to acoustic analysis.
Sound and its characteristics: An introduction to the nature of sound, its definition, and characteristics such as frequency, amplitude and duration. Discuss the different types of sound, including tones, noises, and impulses, and their importance in the context of acoustic analysis.
Sound Transduction: Explaining the process of converting sound waves into electrical or digital signals that can be analyzed by computer systems. Discussion of the different types of sensors and microphones used in acoustic analysis and their applications.
Acoustic Characteristics: Presentation of various parameters and measures used to describe acoustic properties, such as SPL (Sound Pressure Level), sound frequency range, reverberation time, and the distribution of sound in space.
Sound Spectrum: Explain the concept of sound spectrum, which describes the distribution of sound energy as a function of frequency. Discussion of spectral analysis methods, such as FFT (Fast Fourier Transformation) analysis and their importance in sound characterization.
Room Acoustics: Presentation of basic concepts related to sound propagation in rooms, such as diffusion, absorption and reflection of sound. Discussion of methods for modeling and measuring room acoustics and their applications in acoustic design.
Digital Audio Signals: An introduction to basic digital audio processing concepts such as sampling, quantization, and coding. Discussion of various audio file formats and audio compression methods.
Acoustic analysis methods: Presentation of various techniques and tools used for sound analysis, such as time-frequency analysis, Sound Energy Level analysis or analysis of acoustic signals using artificial intelligence methods.
FEM (Finite Element Method) – FEM is a numerical technique used to model and analyze complex acoustic structures such as buildings, vehicles or devices. In the context of acoustic analysis, FEM enables the simulation of sound propagation through various materials and spaces, which allows the assessment of the impact of structures on sound and vibration emission and distribution and the identification of areas requiring acoustic optimization.
Acoustic Models: Acoustic models are mathematical or computer representations of acoustic phenomena in a given environment. They can be used to simulate sound propagation in various conditions, from open spaces to closed rooms. These models allow the prediction of noise levels in various scenarios and the design of countermeasures to reduce the negative impact of noise on people and the environment.
Environmental Noise: Environmental noise includes all unwanted sounds generated by human activities in natural surroundings, such as traffic, industry, airports and commercial activities. Environmental noise analysis aims to assess its effects on people and the environment and develop noise reduction strategies to improve quality of life.
Noise Rank: Noise rank refers to the assessment of noise levels from given sources at a given point or area. It can be used to classify areas as more or less noisy and to identify sources that require action to reduce noise levels in a very optimized way.
Noise Reduction Strategy: A noise reduction strategy encompasses a set of actions intended to reduce the noise level in a given environment. This may include the use of acoustic insulation, structural modifications, noise reductions using silencers, housings etc..An effective noise reduction strategy takes into account both technical and financial to achieve optimal results.
Sound Pressure Level – Sound Pressure Level (SPL): SPL is a measure of sound pressure expressed on a logarithmic scale. It is a commonly used measure in acoustic analysis to assess noise levels in various environments and to normalize noise in accordance with regulations and standards.
Sound Power Level – Sound Power Level (Lw): Lw is a measure of the total sound power emitted by a source, regardless of its surroundings. It is used to characterize the acoustic properties of devices, machines and other objects, and to assess their impact on the environment. SWL is a key parameter in the design of devices with limited permissible noise levels.
By understanding these basic concepts, the reader will be ready to deepen his knowledge of acoustic analysis and its applications in various fields.
Methods and tools of acoustic analysis
One of the basic methods of acoustic analysis is the statistical one, that uses many measurements of the same type of tested object, but for different sizes, operating states and different structures.
The other form of this method is to examine various elements of a given object separately, selecting the best ones in order to assemble them into the best possible tested element. For example, selecting the best materials to create door leaves and frames, then measuring the insulation of several gaskets and finally assembling the door from the best selected frame, door and gasket.
A very effective method of analysis is the construction of an acoustic model. It is a type of computer simulation of the noise environment. Thanks to this method, we can achieve two things: firstly, we can build the so-called noise ranking, i.e. recognize the structure of noise and obtain data about which source contributes the most to this structure. On this basis, you can design an acoustic solution that is the best and cost-optimal answer to the problem
We also use theoretical analyses. This is nothing more than a study of the available literature. we search articles and other sources to see if there is a publication available that addresses a specific problem
Applications of acoustic analysis in various fields
Acoustic analysis is the basis of the process in which we specialize, i.e. acoustic optimization of products. Optimization is used in various fields. It applies to both structural elements (like walls and glazing) and complete machines and devices, such as washing machines and dishwashers.
During the analysis, first of all we have to know what acoustic parameter we want to optimize. In the case of industrial installation, we most often deal with the noise it emits to the local environment. Interiors are mainly about work stations and employees’ exposure to noise.
When it comes to machines and devices, there may be more parameters. These are parameters such as noise emission level, acoustic power level, total level, noise spectrum.
We analyze the operation of the machine and acoustic conditions in the whole spectrum – low or high frequency range.
Acoustic mapping of cites is a whole other application of acoustic analysis. The whole sequence of tasks is necessary for comprehensive acoustic and non-acoustics data that is then used to create a strategic noise map. All leads to a computational model representing the acoustic landscape of an entire city. Such maps are created by specialized companies experienced in environmental acoustics. They enable more informed urban spatial planning and identification of major noise sources in the surroundings, facilitating actions aimed at reducing annoyance for residents.
Strategic noise maps serve as a primary source of information used for:
- Informing the public about noise-related threats in the environment.
- Collecting data for state environmental monitoring.
- Creating and updating noise protection programs.
- Creating noise protection action plans.
- Strategic and spatial planning.
It is a multi-layered document containing various aspects related to noise emission, immission, and impact of each noise source and indicator. Strategic noise map largely depends on the data and analysis entered into the model.
Acoustic properties of materials – how do we measure them?
When it comes to materials, we distinguish three basic properties:
Acoustic insulation – it tells us how high the material’s impermeability is in terms of sound. Acoustic insulation can be further divided into the origin of sounds. The material has insulating properties against airborne sounds (e.g. music spreading in space) and insulation against impact sounds, e.g. steps noise.
Sound absorption coefficient. Most often, we analyze the so-called Reverberation sound absorption coefficient on material in a large sample, approximately 10 to 12 m2 of material in a reverberation chamber. The coefficient is dimensionless, ranging between 0 and 1, where 0 means complete lack of absorption in a given band and sound reflection, and 1 means complete absorption. Additionally, we also examine the Physical Sound Absorption Coefficient. The difference between it and the reverberation coefficient is that in the case of the former the angle of incidence of the sound wave is 90 degrees, while the latter assumes the average for all angles of incidence of this wave.
Sound diffusion – we check how sound is diffused by a given material. We emit sound at a given angle and then observe the reflection of this wave upon contact with a given material.
Overview of acoustic analysis software
Acoustic analysis software is an essential work tool for acousticians and engineers. There are many different tools available on the market, each with its own uses, unique features and benefits. In our company we use the following software:
- Odeon Industrial and combined – a program used to work on the acoustics of all types of interiors, from a factory hall to a concert hall.
- CadnaA and IMMI – to the propagation of industrial and traffic noise to the outside
- SonArchitect – which is used to analyze building acoustics
- Artemis – one of the most important programs we use in vehicle and machine acoustics, psychoacoustics and vibration analysis. The program is also very functional for unusual laboratory measurements.
- Insul – a program for simulation and measurement of acoustic insulation, most often of building elements. Thanks to it, we examine the resultant insulation of an object that was designed and built in a simulation.
Challenges and the future of acoustic analysis
Applications of acoustic analysis will continue to develop. In industrial acoustics, the future of acoustic analysis will certainly be dictated by the increasing amount of data that will be received on the one hand and the increasingly far-reaching automation of processes, including measurements, on the other.
In the future, the number of factors emitting noise will increase (for example, the number of machines in a given plant). Therefore, acoustic analysis methods and tools will be developed in order to obtain data faster and more accurately and, whenever possible, suggest the best, ready-made solutions to the analyst.
Product acoustic optimization is another area where acoustic analysis will play a key role. On its basis, increasingly better sound-absorbing materials will be developed. This is necessary, for example, in the case of building elements, where the thickness of walls or windows is of great importance and these are parameters that cannot be modified (due to project limitations), so sound-absorbing materials must be more effective. In that case metamaterial may be the answer.
For all this to be possible, the analysis itself must also change. In the future, it will be dominated primarily by simulation and virtual construction of acoustic prototypes(?) This is necessary primarily due to the cost of conducting analysis on physical elements, the pace and course of the entire analysis process, which should ideally be shortened as much as possible, and the number of available variants and situations. The use of simulations allows for the construction of a very wide range of scenarios using various solutions. In such a situation, choosing the best solution is simple.
Why is acoustic analysis important?
Acoustic analysis is the basis for working with acoustics in general. It is not only used to obtain data, this process concerns research and measurement, it is a form of observing and asking questions. The analysis forms an answer for us and thanks to it we develop a solution. The analysis allows you to reduce the costs and time needed to suppress noise, shape sound or get rid of vibrations that negatively affect the object or environment.
Acoustic analysis – who conducts it?
Unlike simply carrying out a measurement, acoustic analysis should be carried out by a specialist in acoustics. This is mainly because the acoustic analysis should include a solutions section. KFB Acoustics, with a team of acousticians and technological resources, specializes in this approach.
Acoustic analysis – where to perform it?
The place where acoustic analysis is performed depends on the purpose of this analysis. It depends on what is the object of our analysis. The acoustic insulation of walls, windows and doors in existing object must be measured where they are located. For obvious reasons, measurement and analysis in environmental acoustics, creating noise maps and creating solutions for reducing noise from transport infrastructure are also performed in this way. This data is then usually used to build an acoustic model in the team’s workplace.
When it comes to cars, mobile equipment or machines, ARIC (Acoustic Research and Innovation Center), our research and development center, has special infrastructure for accurate acoustic analysis of this equipment. Acoustic analysis and measurements are made in acoustic chambers, which enable obtaining very accurate data. In the case of vehicles, KFB Acoustics has an acoustic dynamometer equipped with a 3D laser vibrometer, which is one of the most modern centers of this type in the world.
Additionally, it is worth ensuring that the laboratory commissioned with acoustic analysis or acoustic optimization of products has appropriate certification, e.g. standard 17025, which is the basic criterion used for the accreditation of research and calibration laboratories, introduced standardized test methods. KFB Acoustics constantly strives to expand the scope of accreditation and strictly apply standards established by national and European law.