The acoustics of products have a considerable influence on perceived quality: products that operate quietly are perceived as being of higher quality, although the technical efficiency of the device may be independent of this subjective perception. In product tests, acoustics are therefore an important criterion influencing market success.
The problem: Unwanted noise generation
Noise can occur as an unwanted side effect during the operation of products and devices. Various causes can be identified here:
Noises are caused by flow phenomena. The cause is a detachment or stalling of the flow. Such a stall occurs, for example, due to
- Abrupt changes in cross-section in the flow channel ("steps")
- Unfavorable inflow of elements in the flow channel (Kármán vortex street as a possible consequence)
- Reduced flow cross-section (leading to higher flow noise)
Noise due to structure-borne sound
The vibration of bodies or components can also lead to noise emission. This structure-borne sound is triggered by striking, rotating or oscillating forces, for example in an electric motor for driving a fan wheel. The mechanical excitation of the body or component can also be caused by a flow. In this case, the component is subjected to unfavorable flow, resulting in vibration excitation.
The solution: Troubleshooting by M.TEC Engineering
As product developers with many years of experience, M.TEC engineers know the physical relationships involved in noise generation and can influence them within set boundary conditions. We provide innovative and economical acoustic solutions for your technical products.
Targeted control of noise generation: Elimination of disturbing noises
There are various ways of modifying a disturbing noise so that it no longer attracts negative attention:
- Reduction of the noise
- Complete elimination of the noise
- Change of the noise towards a more pleasant sound
The challenge in eliminating the causes is primarily to maintain functional performance and efficiency. The basis for this is a holistic, detailed analysis of the noise generation. This results in numerous approaches to solutions, which can be evaluated and weighed up in terms of their efficiency and cost-effectiveness.
If a sound is desired, but the sound quality achieved is not satisfactory, there are various approaches to influencing the sound. In this case, the sound quality is adjusted in a targeted manner.
Methods and development tools
Methods for measuring and simulating acoustics are constantly improving. These include the following aspects, among others:
Methods for measurement and simulation of acoustics @cont.HeadlineType>
- Acoustic simulation
- Modal analyses
- Natural frequencies, natural modes, modal damping
- Developing vibration-optimized designs
- Implementing vibration-reducing measures at a later stage
- Binaural noise measurement
- Acoustic transmission paths via structure
- Simultaneous imaging of solids and multiple acoustic media (air, water, etc).
- Investigation of acoustic and structural natural frequencies with and without damping
- Frequency response analysis with acoustic-structural coupling
- Quasistatic observation of the frequency spectrum
- Evaluation at arbitrary coordinates or reference points
- Determination of structural and acoustic natural vibration modes
- Sinusoidal excitation on structure (e.g. loudspeaker membrane, piezo, etc.)
- Investigation of material damping over sound propagation path
- Transient acoustic investigation
- Observation of sound wave propagation in any medium (air, water, metal, etc.)
- Temporal resolution of wave fronts over sound pressure
- Explicit FEM
- Shock wave propagation (e.g. explosions under water)
- Example: Pulse excitation and sound wave reflection