Psychoacoustics and subjective assessment of variable-speed hydraulic drives

  Acoustic Measurement of a Pump Copyright: © ifas

The electrification of industrial mechanical engineering is becoming increasingly widespread in both stationary and mobile applications. Especially in the field of mobile machines (excavators, wheel loaders, etc.), this leads to the hydraulic drive technology, which has so far been lost in the noise level of the combustion engine, becoming audible to the human ear and even perceptively coming to the fore. Pumps are the dominant noise source in hydraulic systems. They convert mechanical energy into hydraulic energy and can be found in almost all systems. The noise emission depends on the pump design and is still the subject of current research. However, only the noise level is considered, not the psychoacoustic parameters. The psychoacoustic classification of how people subjectively perceive and evaluate the noises emitted by different pump types - especially depending on speed and load - has not yet been researched. In addition, existing psychoacoustic models cannot be used to predict subjectively perceived annoyance, as they only allow product-specific statements. The acoustic and psychoacoustic properties of variable-speed hydraulic drives are investigated within the framework of the project.

 
Benefit Procedure

Consideration of the subjective hearing sensation of hydraulic drives with variable speed

Sound measurements (axial piston pump and internal gear pump) in the sound measurement room

Comparison of different pump designs (comparison of axial piston pump with an internal gear pump) regarding psychoacoustic parameters

Evaluation of sound measurements in terms of sound pressure levels and psychoacoustic parameters (loudness & sharpness)

Correlation regarding measured psychoacoustic quantities and the real subjective hearing sensation

Performing listening tests by the ifp

Model for the evaluation of subjective hearing sensation for hydraulic drives with variable speed Modelling of the subjective hearing sensation

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Psychoacoustics of pumps

Electrification in the field of mobile machinery is becoming more and more prevalent in the compact segment. Particularly in the area of mobile machinery (excavators, wheel loaders, etc.), this means that the hydraulic drive technology, which was previously drowned out by the noise level of the combustion engine, becomes audible to the human ear and comes to the forefront of the operating noise. Pumps are the dominant source of noise in hydraulic systems. They convert mechanical energy into hydraulic energy and are found in almost all machines. The noise emission depends on the pump design and is still the subject of current research. However, only the noise level is considered, not the psychoacoustic parameters. The psychoacoustic classification, how people subjectively perceive and evaluate the noise of different pump types - especially depending on speed and pressure - has not yet been researched. Furthermore, existing psychoacoustic models cannot be used to predict the subjectively perceived annoyance, as they only allow product-specific statements. Within the framework of the research project, the acoustic and psychoacoustic properties of variable-speed pumps were investigated.

Objective

Within the framework of this research project, the operating noise of variable-speed drives was investigated. For this purpose, the operating noises of an axial piston pump and an internal gear pump were recorded instrumentally in sound measurements and the psychoacoustic parameters were correlated with subjective perceptual judgements and noise evaluations from listening tests. In doing so, ifas is working together with the Institute for Psychology (IfP) at RWTH Aachen University.

 
 

Sound measurement of hydraulic drives with variable speed

Within the scope of this research project, an axial piston pump and an internal gear pump were examined. For this purpose, both pump types were measured in the sound measurement room and the noise level, loudness and sharpness were recorded instrumentally. The essential operating parameters of pressure and speed were varied in a targeted manner.

 

Conduct listening tests and regression analyses to predict the subjective hearing sensation

As part of this research project, listening tests were conducted at the Institute of Psychology (IfP). In the listening tests, the sounds of the pumps were played to the test persons in pairs and they had to evaluate which of the two sounds was perceived as more pleasant, this method is called dominance pair comparison. After completion of the listening tests, the results were analysed by means of regression analyses and models were created to assess the subjective hearing sensation.

 

Acknowledgement

This research project was carried out within the framework of the project OPSF507 "Psychoacoustics and subjective assessment of variable-speed hydraulic drives", which was funded within the framework of the Excellence Strategy of the Federal Government and the Länder for the promotion of science and research at German universities.
This was a joint project carried out by ifas together with the Institute of Psychology (IfP) with Univ. Prof. Dr. Sabine Schlittmeier.

 

Publications

Title Author(s)
Audiovisuelle und kognitive Effekte bei der Lautheitsbeurteilung eines Baggers mit Hydraulikpumpe
Abstract (2021)
Georgi, Markus
Pietrzyk, Tobias
Schmitz, Katharina
Schlittmeier, Sabine Janina
Psychoacoustic Evaluation of Hydraulic Pumps
Contribution to a book, Journal Article (2021)
Pietrzyk, Tobias
Georgi, Markus
Schlittmeier, Sabine Janina
Schmitz, Katharina (Corresponding author)
Messtechnische Erprobung einer elektro-hydraulischen Linearachse mit High-Speed Antrieb
Contribution to a book, Contribution to a conference proceedings (2021)
Pietrzyk, Tobias (Corresponding author)
Schmitz, Katharina