## 1 Introduction
The third and final publication of these series explained structure-borne noise. The researchers also suggested possible improvements for manufacturers to decrease structure-borne noise in vacuum cleaners. [PERSON] et al. [15] designed a new centrifugal impeller to improve the noise quality of vacuum cleaners. The aim was to increase the perceived noise quality and not only to reduce the overall noise level. The optimization process was based on two different general noise exposure models. They finalized their propeller design with triangular flow channels. In listening tests, they found that it was possible to make a user-oriented design change based on the psychoacoustic findings. [PERSON] and [PERSON] [16] performed sound power level measurements on a handheld vacuum cleaner to identify the main components of the noise. After analyzing the noise, they implemented modifications on the fan casing and the blade distribution, which changed the blade pass frequency. They evaluated the modifications in terms of their preference in jury testing, especially considering the magnitude of the tonal components in the overall noise. [PERSON] et al. [17] investigated the effect of modifications on fans and motors on an upright vacuum cleaner in another publication. They found that prominent tonal noise is created by an interaction between the electric motor cooling fan and the surrounding gussets and posts. They removed these elements in an alternating fashion such that the first blade passing frequency of the electric motor cooling fan was eliminated. [PERSON] et al. [18] made modifications to a canister vacuum cleaner to reduce its noise. They pointed out that the noise of a canister vacuum cleaner consists of the blade passing noise generated by motor and the aerodynamically induced airborne noise. Two different noise reduction methods were used: the introduction of sound insulation panels made of porous expanded polypropylene and honeycomb noise filters. After these modifications, the total noise level was reduced by 7.4 dB(A), with a reduction in suction power of only 0.93%. This study focuses on understanding the general sound characteristics of vacuum cleaners and their annoyance perception. There are many different brands and types of vacuum cleaners with different designs in the market. The differences in design result in differences in noise characteristics: some of the devices are loud, whereas some of them have higher sharpness values. Some of the devices have distinct tonal components, whereas some of the designs are free from tonality. Then, the main question is what kind of canister-type vacuum cleaners should be selected and recorded to investigate, as much as possible, the variability in noise that can be observed, so that the variability in the market can be properly represented? What is the generic vacuum cleaner noise, and how much variability can there be between different models? The goal is to select proper samples from the market such that these selected samples can represent the variability in noise. To reach this goal, canister-type vacuum cleaners are selected such that the selected samples can represent the variability in noise. The main aim in this study is to select devices such that the selected samples can represent the variability in noise from canister vacuum cleaners. First, the basic characteristics of vacuum cleaner noise are provided for the selected examples. Then, the ranges of calculated psychoacoustic parameters for selected vacuum cleaners are presented. Variability in the acoustic and psychoacoustic parameters on different vacuum cleaners is discussed to derive common characteristics of canister-type vacuum cleaner noise. This variability is then related to the available information on the noise generation mechanisms of vacuum cleaners in the literature. This observed variability in noise samples in the market is used to set up listening experiments and their ranges. Afterward, two sets of listening tests are conducted in this study.