have been accumulating remain unprocessed. The introduction of 

 mechanical instruments for sound recording and sound analysis into 

 the study of bioacoustics has brought present-day research to a level 

 far above that of previous work. Present-day data arouse the interest 

 of biologists of the widest variety: evolutionists, ecologists, and 

 also specialists in the field of acoustic bionics. The problems of 

 communication and mechanisms for coding and communicating vocal 

 information under specific environmental conditions thus acquire 

 general biological interest and significance. 



From the time at which the early works of N. I. Dergunov (1925) 

 and A. I. Promptov (1927) appeared, the problems of local dialects 

 and geographical voice variability in birds have been intensively 

 studied in the USSR (Promptov, 1930; Kistyakovskii , 1958; 

 Mai' chevskii, 1958, 1959, 1963,; Dement'evand Il'ichev, 1963; Simkin 

 and Il'ichev, 1963; and others). In addition to these investigations, 

 the following original works are of great interest; A. N. Promptov, 

 1944, 1956; A. N. Promptov and E. V, Lukina, 1945. These works deal 

 with the mechanisms of the above phenomena. 



At the end of the 19th century, the problem of geographical 

 voice variability began to be studied with material on other animal 

 groups; it was established that amphibians, insects and apparently 

 mammals as well as birds are subject to the phenomenon of geographi- 

 cal voice variability, and can thus be utilized as models for study. 

 Immense quantities of data have been accumulated over the last years. 

 The following works are of special interest: W. F. Blair, 1955, 

 1956, 1958; H. Allard, 1957; B. Alexander and Borror, 1956; A. Faber, 

 1953; G. Pierce, 1948; H. Frings, 1956. The above authors have 

 collected extensive material on different species of insects and 

 amphibians. No less important is the contribution of ornithologists: 

 Marler, 1956; Thorpe, 1961; Sauer, 1955; Benson, 1948; and others. 



An innovation which considerably broadened the scope of bio- 

 acoustics was the recent attempt to conduct a parallel study of the 

 voice and hearing mechanisms as a single functional system. Reviews 

 on this subject by J. Schwartzkopf f , 1962, and by G. Tembrock, 1959 - 

 which examine the factual material precisely from this point of view - 

 have opened new and unexpected vistas. 



Among these is the recently outlined division of geographical 

 voice variability into two basic categories: adaptive variability 

 and nonadaptive variability. Adaptive variability embraces those 

 cases in which the voice serves to indicate the setting apart of 

 individuals or a group of individuals and thus the territory they 

 occupy. This is biologically significant in that it allows animals 

 to utilize the possibilities offered by their ecological niche and 

 thus enables the species to flourish, 



