Machinery sound quality affects the commercial value of a product. However, the relative importance of sound quality with respect to the product's commercial value isn't clear. If the value of the sound quality of machinery noise could be evaluated using monetary units, manufacturers could estimate the effectiveness of any improvement. In a previous study, to evaluate the economic value of the sound quality of machinery noise from vacuum cleaners, two kinds of experiments were conducted, in which participants evaluated their will to purchase for twenty-five kinds of vacuum cleaners characterized by six attributes such as manufacturer, price, and A-weighted sound pressure level (dB) and sharpness (acum) of the machinery noise. In one of the experiments, the attribute of machinery noise was A-weighted SPL, and in the other experiment, sharpness. Each of the six attributes had two to five characteristics. Three values were set up for the attributes of A-weighted SPL and sharpness; 64, 59, 54 dB in A-weighted SPL and 2.46, 2.21, 1.96 acum in sharpness. The rating results were applied to conjoint analysis. In each experiment, to inform participants of the characteristic concerning the "machinery noise" attribute, machinery noises with three values were presented to them in the explanations of the experiments. In general, in the conjoint experiment, participants are presented with only stimulus cards, but not sound stimuli, to inform about the product characteristics including the aspect of machinery noise. Here, to discuss the effect of sound presentation on results including the economic value of sound quality, similar experiments were conducted; however, participants were not presented with the machinery noises in the explanations concerning the attributes of "machinery noise". As a result, in each attribute characterizing vacuum cleaners, the difference of the importance between the previous and present studies was not so remarkable. From the economic valuation of sound quality, the estimated values were US$ 17.2 for a 5 dB reduction and US$ 53.1 for a 0.25 acum reduction. These estimated values varied from those obtained in the previous study. The explanations concerning the "machinery noise" attribute in the present study instead of sound presentation might affect estimated values.