PURPOSE: To store information in tiers by allocating the information of lower level to a signal string of short-time scale and those of upper level to a signal group pattern or power spectrum value of long-time scale.

CONSTITUTION: The signal string consists of clusters c1, c2, .... To attain such a sorting, a pulse interval longer than 10ms is regarded as a cluster interval. The signal string sorted in clusters is regarded as the information of tier 1. And, a word that constitutes a sentence is allocated to each one of the clusters. Then, by measuring the internal of each cluster as regarding a pulse interval longer than 2ms as a cluster interval, an information consisting of lower cluster groups such as a tier 2 is obtained. To each of these lower clusters, a character constituting a word is allocated. Further, as to the internal of the lower cluster, the arranging rule of the bit string is examined by upgrading the measurement resolution of the pulse interval up to 0.5ms. To the information of tier 3 thus obtained, the bit arranging rule to define a character is allocated.