Noise is increasingly the subject of new regulations for the protection of human health and safety as well as for improving the environment in general. As well as sound levels, the perceived sound quality of products from washing machines to vehicles is often an important part of the customer buying decision so must be considered during product development. m+p Analyzer for noise and vibration measurement and analysis provides a full range of capability for these applications. Real-time fractional octave filters satisfy all acoustic applications from simple sound pressure, sound power for equipment legislative requirements, intensity mapping to isolate sources to sound quality metrics for product refinement.
Fully compliant with ANSI S1.4 and IEC 61672 type 1 sound meter specifications including A/B/C weighting and 1/1 to 1/24 octave spacing from 1 Hz to 100 kHz even with high channel counts. Response types include fast, slow, impulse, custom, linear average and LEQ.
Sound Intensity and Sound Intensity Mapping
Real-time sound intensity measurements use a standard dual microphone intensity probe calculating real-time pressure, intensity and pressure residual intensity index. This technique is directionally sensitive making it ideal for source localization or background noise cancellation. It enables accurate measurements directly in the field without the need for expensive acoustic laboratories. A wire frame 3D model of your equipment under test is used to guide an operator around a sequence of sound intensity measurements. These results are then mapped to the colour coded 3D image for identification of the principal sound sources and their levels.
Sound power is an absolute measure to determine the noise emissions of a product. All equipment from PC fans to heavy machinery must have published sound power emission levels for environmental regulation. m+p Analyzer wizards guide the operator through the maze of requirements in the ISO 374x standards and, using the intensity measurements, the ISO 9614 standards. The latter method has high tolerance to background or reverberation effects so is suitable for use in most on-site environments rather than needing expensive anechoic chambers or field sites. More specialized applications such as wind farm methods like IEC standard 61400-11 and tonality using ECMA-74 are also available.
Human perception is critical to improving product competitiveness: Designers face the challenging task that they not only have to reduce the product noise level, but also have to find the “right” sound that attracts the customer. Sound quality metrics can be used to rank and evaluate different product designs. The basis of the m+p Analyzer Sound Quality Analysis is Zwicker loudness according to ISO-532 and DIN-45631. Functions are available both as online and post-processing analysis and can be computed from either narrowband or octave band spectra. Pitch and warble analysis provides metrics for squeak and rattle applications.
Impedance Tube Testing
Impedance tube measurements allow the calculation of important characteristics of acoustic materials such as absorption coefficient, reflection coefficient, impedance and transmission loss coefficients according to ISO 10534-2, ASTM E1050-12 or ASTM E2611-17. Depending on the test standard, measurements are taken using either two or four microphones. The desired parameters are calculated and all relevant information is summarized in a report.
Alongside environmental noise, evaluation of other human factors such as hand-arm vibration from the use of power tools or the evaluation of whole body vibration from riding in vehicles as per the various ISO and BS standards are available. These include C/D/H/K weighting and functions such as VDV (vibration dose value) calculations. In conjunction with sound quality algorithms these vibration results can form a comprehensive set of metrics for vehicle comfort assessment and refinement engineering.