352 



NOISE 



though a considerable adaptation takes place 

 with prolonged exposure as far as the non- 

 auditory ill effects are concerned, the evi- 

 dence suggests but does not fully substanti- 

 ate the conclusion that this adaptation is not 

 complete. Nearly all studies on the effects 

 of noise have noted individual differences 

 between subjects, making broad generaliza- 

 tions hazardous. In spite of this fact, al- 

 most no efforts have been directed toward 

 the objective of screening "noise-prone" in- 

 dividuals, i.e., those most susceptible to 

 noise annoyance or noise trauma. 



Areas for Further Investigation 



One general area demanding research at- 

 tention is obviously the selection and screen- 

 ing of those persons least susceptible to noise 

 annoyance and noise trauma, and most read- 

 ily adaptable to noise conditions. The re- 

 port of Wilson (98) mentioned above is a 

 beginning in this area. 



The fact that there are numerous wide- 

 spread subjective reports of increased gen- 

 eral fatigue in the presence of high noise in- 

 tensities suggests the need for a thorough 

 systematic investigation in this area. What 

 is the basis, physiological or otherwise, of 

 such reports? Measures of annoyance and 

 fatigue have not been entirely satisfactory 

 and need to be developed, if progress in this 

 area is to be made (45). 



The studies of noise as it affects physical 

 functions have for the most part been defi- 

 cient both with respect to the levels and kind 

 of noises employed and with regard to the 

 duration of exposure periods. If such 

 studies are to be immediately applicable to 

 problems of submarine warfare, noise levels 

 should vary between 100 and 130 db and the 

 subjects should be repeatedly exposed for 

 continuous periods of ten or more hours' du- 

 ration. It is possible that the long-run ef- 

 fects on such functions as vv^ell as on psycho- 

 physical tasks are obscured by long periods 

 of quiet interposed between experimental 

 sessions. Moreover, the factors of motiva- 

 tion and suggestion, both of which are diffi- 



cult to control, merit more attention than 

 they have generally received in the experi- 

 mental studies herein reviewed. 



The nature and degree of auditory trauma 

 have been relatively well estabhshed both 

 experimentally and by clinical observations, 

 so that it is reasonably certain that long ex- 

 posure to noise levels of 120 db (conditions 

 approximating those in some submarines, 

 airplanes and small surface vessels) will cer- 

 tainly produce a temporary, and probably a 

 permanent, decrease in acuity, especially in 

 the range from 2,000 to 4,000 c.p.s. Al- 

 though it is beyond the immediate scope of 

 this report, it is also apparent that studies 

 of vibration in the subauditory range and 

 in the ultrasonic range are likewise impor- 

 tant. In this connection, D. E. Goldman 

 at the Naval Medical Research Institute, 

 Bethesda, Maryland, is conducting perti- 

 nent research. 



Finally, a field study of duty assignments 

 aboard submarines may be necessary to dis- 

 cover the extent to which personnel move 

 from high noise levels to assignments de- 

 manding high auditory acuity. It may be 

 that a problem of noise protection exists 

 which is comparable to that of dark adapta- 

 tion of bombardiers or night lookouts. That 

 is to say, men assigned to duties demanding 

 a high degree of auditory acuity should obvi- 

 ously be protected from high noise levels for 

 extended periods prior to taking over their 

 stations. The extent to which such men are 

 not now protected, and the extent to which 

 lack of protection adversely affects perform- 

 ance of duty, need study. 



Refekences 



1. Atkinson, M. Tinnitus aurium: observa- 



tions on the effect of curare on loudness 

 level. Ann. Otol., etc., St. Louis, 1946, 

 55, 398-405. 



2. Baker, K. H. Pre-experimental set in dis- 



traction experiments. /. appl. Psychol., 

 1937, 16, 471-488. 



3. Berrien, F. K. The effects of noise. Psy- 



chol. Bull., 1946, 43, 141-161. 



4. Berrien, F. K., & Young, C. W. Effects of 



acoustical treatment in industrial areas. 

 /. acoust. Soc. Amer., 1946, 18, 453-457 



