206 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1946: 
tion without the complications appearing in sounds that are rich 
in harmonics. But these song patterns are obviously revealing and 
illustrate well the possibilities of sound portrayal. With such pat- 
terns as these it will be possible to analyze, compare, and classify 
the songs of birds, and, of even more importance, it will be possible 
to write about such studies with meaningful sound pictures that should 
enable others to understand the results. The same argument applies 
to an almost endless variety of inaudible as well as audible sounds 
of both natural and mechanical origin. Even such low-frequency 
oscillations as those accompanying the beat of the heart may be re- 
corded slowly and converted to the sound spectrogram form by high- 
speed reproduction. Also frequencies beyond the upper range of the 
ear may be shifted to the audible range by well-known methods so 
that sound spectrograms may be made in a region where recording is 
less difficult. 
In conclusion, it is well to point out that this is necessarily an in- 
complete story of the sound portrayal development. Nothing has 
been said about several important points: for example, use of a log- 
arithmic frequency scale, and a frequency selection that corresponds 
more closely to the aural experience; and better amplitude represen- 
tation by contours, color, and other means. Some interesting results 
have been obtained in developments along these lines but it seems best 
to reserve them for later discussion. Also, a great deal could be 
said about the need for a modernized alphabet in this age of speed 
when a rapid exchange of ideas and information is increasingly 
important, but this too had better be reserved for some later occasion. 
Many members of the Bell Telephone Laboratories, including both 
engineers and those associated with the experimental training, have 
cooperated in this development work. All have displayed an enthus- 
iastic interest and it is a pleasure to acknowledge their contributions. 
