As quietness of product is recognized as high quality in many industries, the importance of noise control in product development has been increasing more and more. However, due to the requrements of lighter weight and reduction of development cost and time, it is difficult to have enough time for experimental works improving sound insulation performance. Consequently, control of the sound quality of the product becomes important.
Up to now, the noise control was based on evaluation of the physical quantity such as sound pressure level. Even though there is similar sound pressure level, sometimes the impression of the sound may be defferent. Additionally the subjective feeling such as pleasant sound, undesired sound, is difficult to be expressed in physical quantities. So, it is important to introduce subjective evaluations into product development, in addition to noise control based on the physical quantities.
When a psychoacoustic experiment, the subjects evaluate the sound and respond their subjective impressions. These subjective impressions are different among each test subjects. To obtain highly reliable results, a considerable number of subjects are required.
The psychoacoustic evaluation plays a key role in determining the design and development of products in various fields. For example, If there is tendencies or key of psychoacoustic quantities related to "Comfortableness", it is possible to take these results into the noise control design strategy. It is also important for the point to avoid over speculation.
Moreover, in a vehicle, even if the noise level is equal the sound impression will change by timbre. In the case of sports cars that emphasize the sporty feeling, the sound in vehicle should have a tendency to be designed focused on not quietness but "sporty feeling".
Thus, psychoacoustic experiment can assist in the sound design and development field.