抄録
It is not desirable that impact noise changes by temperature environment, because absolute value is measured. There are main three factors by change of aging or temperature, e.g. impact source, vibration characteristics of slab and natural frequencies in receiving room. It is not so negligible their influence in the region of low-modal density that impact noise with heavy impact source is evaluated in particularly low frequency range. Then, systematic comparable samples were used, i.e. impact noises in bare slab of laboratory. Measures to reduce influence by three factors mentioned above were taken step by step and shown the results.
