240 



VOICE COMMUNICATION, I 



/ / / 



el-b6w;at-tract;foo-lish (18, pp. 4-6, 11-12; 

 19, pp. 4-11). 



Audibility tests for alternative locutions. 

 On the basis of these various correlates of 

 audibihty in noise, an experienced phonet- 

 icist could probably set up a relatively sat- 

 isfactory standard phraseology by inspection 

 alone. The selector may also take advan- 

 tage of a known list of 1000 highly audible 

 words, chosen from all the familiar words 

 in the English language, for each of which 

 the audibility rating in noise has been estab- 

 lished by extensive experimentation (7, pp. 

 57-63, 89-108). In the imperfect state of 

 our present knowledge, however, it is safest 

 to make only a preliminary selection of phra- 

 seology on the basis of inspection alone, and 

 to rely on a standard "audibility test" to 

 weed out words which, because of low audi- 

 bility or tendency to mutual confusion, 

 should have no place in a final list. 



The conduct of an audibihty test is fully 

 described in 7, pp. 5-1 1 and 86-88. A num- 

 ber of speakers read the alternative words 

 and messages to be tested to a group of 

 listeners, over the submarine intercommuni- 

 cation system, against a background of die- 

 sel-type noise. The "audibility rating" of 

 a word is the number of times it has been 

 correctly identified, expressed as a percen- 

 tage of the total opportunities for identifica- 

 tion. The available evidence indicates that 

 the audibility of a word is to some extent 

 specific to the response characteristics of the 

 equipment over which it is spoken, the kind 

 of background noise against which it is 

 heard, the local dialects and the educational 

 levels of the talkers and listeners, and the 

 competitive context in which it is presented 

 (7, pp. 77-86). For the most precise and 

 valid measurement of the audibility of alter- 

 native words and phrases, all these variables 

 ought to be sampled, insofar as they are to 

 be expected in the specific submarine situa- 

 tion. Nonetheless, present indications are 

 that these various factors are not so specific 

 in their effects but that a vocabulary tested 

 over a single interphone, by a fairly repre- 



sentative group of personnel, against one 

 type of diesel noise, will remain highly au- 

 dible under any foreseeable changes in the 

 conditions of communications on board sub- 

 marines. 



Eeferences 

 A. General 



1. Black, J. W. The quality of a spoken vowel. 



Arch. Speech, 1937, 2. 



2. Fletcher, H. Speech and hearing. New 



York: D. van Nostrand, 1929. 



3. Laase, L. T. The effect of pitch and in- 



tensity on the quality of vowels in speech. 

 Arch. Speech, 1937, 2. 



4. Miller, G. A. The masking of speech. Psy- 



chol. Bull., 1947, 44, 105-129. 



B. OSRD Reports by the Psycho-Acoustic 

 Laboratory, Harvard University, NDRC 



5. OSRD No. 987. The problem of selecting and 



training personnel for communication in in- 

 tense noise. M. H. Abrams & J. E. Karlin. 

 Nov. 10, 1942. 



6. OSRD No. 1571. Collected informal communi- 



cations on the basic audibility of English 

 words for use as oral codes, alphabetic equiva- 

 lents, etc. M. H. Abrams, J. E. Karlin, 

 J. Miller, F. H. Sanford, & S. S. Stevens. 

 July 9, 1943. 



7. OSRD No. 1919. Vocabularies for military 



communication in noise. M. H. Abrams 

 & J. E. Karlin. Aug. 25, 1943. 



8. OSRD No. 2038. Studies on the effect of noise 



on speech commmunication. J. P. Egan, J. 

 Miller, M. I. Stein, G. G. Thompson, 

 & T. H. Waterman. Nov. 25, 1943. 



9. OSRD No. 3516. Auditory tests of the ability 



to hear speech in noise. J. E. Karlin, 

 M. H. Abrams, F. H. Sanford, & J. F. 

 Curtis. Sept. 1, 1944. 



10. OSRD No. 4023. Speech in noise: a study of 



the factors determining its intelligibility. M. 

 H. Abrams, S. J. Goffard, K. D. Kryter, 

 G. A. Miller, J. Miller, & F. H. Sanford. 

 Sept. 1, 1944. 



11. IC-71. A portable interphone for rating and 



training talkers in noise. May 1, 1944. 



C. OSRD Reports by the Applied Psychol- 



ogy Panel, NDRC 



12. OSRD No. 1769. A speech interview for the 



selection of telephone talkers. Report No. 1, 

 Project N-109. Aug., 1943. 



13. OSRD No. 1823. A preliminary study of the 



