44 VOLUME 24, No. 4, 2020 * Corresponding author: Anna Yehorova, E-mail address: anna.yehorova@tuke.sk Acta Mechanica Slovaca 24 (4): 44 - 50, December 2020 https://doi.org/10.21496/ams.2020.035 Acta Mechanica Slovaca ISSN 1335-2393 www.actamechanica.sk Acoustic properties of washing machines in terms of customer expectations Anna Yehorova 1, *, Ervin Lumnitzer 1 1 Technical University of Kosice, Faculty of Mechanical Engineering, Department of Process and Environmental Engineering Abstract: The presented paper focuses on the possibilities of evaluating the acoustic properties of partial noise sources of household washing machines. The introductory parts are focused on the analysis of the use of a new type of properties, so-called customer-oriented acoustic properties of the product. The next part focuses on the design of an evaluation methodology, which is used for laboratory measurements of psychoacoustic properties. This methodology, after laboratory testing, is used for measurements in real conditions of selling, directly in sales premises. A listening test is proposed, the results of which are used to determine the acoustic properties required by customers. Keywords: Customer-oriented properties, sound, psychoacoustics, sound quality, listening test, laboratory measurements. 1. Introduction Nowadays, the trend is for the products ofered on the market to have a high technical level, for example, a long-term warranty is becoming commonplace. Today it is not a problem to produce a product with good technical parameters and the required service life, but to implement it on the market. For this reason, manufacturers need to focus on those features that have not been at the forefront of their interest so far, but have a certain added value and can increase customer interest in a particular product. This process began with the advent of the so-called industrial product design, especially in the automotive industry. Later, preferences such as recyclability, energy optimization, adaptive and intelligent properties, acoustics, lighting properties, energy feld optimization and many more began to be preferred. One of the attractive areas discussed in this paper is the acoustic design of products, which is related to a number of areas such as visualization of sound generation and propagation, psychoacoustics, simulation of sound propagation, sound perception and the infuence of generated sound on human emotional state. The issue of this paper is becoming increasingly important on a global scale. Several authors deal with the improvement of acoustic properties of various products in their works. Prezelj, J. in the article "Centrifugal fan with inclined blades for vacuum cleaner motor" [2] describes the possibilities of infuencing the alternative geometry of the impeller of a centrifugal fan on its acoustic parameters. The author deals with the reduction of noise and the improvement of the product as a whole from the point of view of evaluation by using psychoacoustic parameters. The process of optimizing the internal noise and vibration of vehicles with the help of sound quality parameters is characterized in the paper "A computational approach for optimizing vehicles' interior noise and vibration" by A.M. Al-Dhahebi [3].