150 
IOWA ACADEMY OF SCIENCE Vor. XXIX, 1922 
A variable single band acoustic filter 
G. W. STEWART 
This is a single band filter constructed by means of a straight 
tube or conduit with branch lines consisting of a volume and a 
tube connected in parallel and with the main conduit, but with an 
alteration at will of the opening into the main conduit. The 
narrowness of the single band can be modified by the modifications 
in the size of this hole without seriously affecting its other charac- 
teristics. The performance of the single band filter reported upon 
is in accord with theory mentioned. 
State University oe Iowa. 
