Relation between distance and pressure of acoustic signal

In this paper, we investigated if the distance can be judged by mutually comparing sound from a source with that from another. We further intended to correlate this sound comparison with the relative distance. It was made clear from the result that the sound loudness exhibited good correlation with the distance. In other words, the distance can be estimated by comparing the sound heard with the standard sound. As for the relation between the distance and the sound heard by the examinee, the consistency index was good and the correlation was consistent. The sound loudness sharply fell with distance, down to about 1 m, and slowly decreased beyond this distance