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From the point of view of acoustical communication, dense fields of reeds are strong acoustical filtre which distorts original sound signal. In this research the rate of sound signals sound insulation in massives of reeds was estimated. As a models were used artificially synthesized, modulated by frequency signals of three frequency lines: 1‐2 kHz, 2‐4 kHz, and 4‐8 kHz with duration of 0.1 and 0.25 msec. For comparison were also used elements of bird songs. The least damping was noted in signals with descending frequency modulation in 8 ‐ 4 kHz range in the upper level of reeds (6 db on 10 m). The most damping were noted in signals with descending frequency modulation in 2 ‐ 1 kHz in the middle level of juncaceous massive(18 db to 10 m). The signals with frequency modulation of 4‐2 kHz were extending better in the upper level of reeds (7‐8 db), whereas in the lower and upper levels were noted dependence of damping rate on duration of sound impulse ‐ the signals with duration of 0.25 mec were damping less than signals with duration of 0.1 msec . The elements of bird songs during their emission in the middle level of juncaceous massive were damping by 15‐20 db on 10 m.

The question of the period of existance of a local dialect is yet to be answered. Were there a changes in time‐and‐frequency parameters of dialects with time? If there were, what parameters had changed? On the basis of original data for 2005 ‐ 2007 period, and archives of Department of Vertebrate Zoology of Saint‐Petersburg State University, the history of local dialect of Redwing (Turdus iliacus) from Saint‐Petersburg's outskirt (Peterhof) was investigated.The archive contains recordings of local dialects of Peterhof for 1960‐1991 period. Until now, the longest period of local dialect observation for this species did not exceed 10 years (Bjerke, 1981). In observed period of 48 years several changes were found. Number of elements in phrase, it's duration, frequency modulation of all elements, their configuration, duration and frequency range. The major changes occurred to the first element of song. It is gradual reduction with time is obvious.