information made it possible to install production testing 

 methods for use in the factory that permitted great improve- 

 ment in the control of the quality of acoustical gear not 

 heretofore realized., By working closely with groups con- 

 cerned with field tests and measurements and making avail- 

 able to them Improved techniques, it was possible to improve 

 the effectiveness of practically all acoustical measurements 

 made at sea„ 



Notable among these projects was the program for the 

 measurement of the noise output from American submarines when 

 operating in combat areas, The acoustical measuring sets de- 

 veloped at the New London Laboratory for this work were all 

 calibrated at regular intervals by the Underwater Sound 

 Reference Laboratories 



Service gear when installed and ready for use had to be 

 subjected to accurate tests and checks if it was to function 

 effecisntly* The acoustic monitor developed at Harvard Uni- 

 versity s and described later in this volume, made possible 

 the checking of the acoustic operation of every destroyer's 

 sonar while at sea. The readings of these monitors were all 

 ultimately referred to the acoustic standards used for cali- 

 bration purposes,, 



As a result of the measurement and standardization pro- 

 gram, much important information and many new instruments and 

 techniques were made available to the engineer and scientist 

 for precision measurements that will find application in many 

 fields of peacetime work. The standard instruments themselves 

 incorporating the wartime advances in the use of new piezo- 

 electric crystals, such as ammonium dlhydrogen phosphate, will 

 find application in many lines of acoustical work c In addition, 

 better methods for the utilization of quartz and Rochelle salt 

 crystals were found as a by-product in the development of 

 better standard instruments,, 



In a similar way, the improvements in the efficiency of 

 magnetostriction devices and electromagnetic instruments will 

 contribute to many lines of peacetime acoustical engineering 

 and related fields „ These latter inprovements were the re- 

 sult of the full utilization of new magnetic materials and 

 fundamental improvements In the theory and practice of mag- 

 netic circuit design,, The power handling capacity of acoustic 

 gear s the necessity for much wider frequency response, and for 

 high fidelity equipment when used with very short pulses and 



33 



