Chapter 8 

 AUDITORY SIGNALS 



W. R. GARNER 



The Johns Hopkins University 



Introduction 



We can consider, for our purposes, that a 

 display is any means of presenting informa- 

 tion. An auditory display, then, is any 

 method of presenting information through 

 our sense of hearing. While speech is by 

 far the most common form of auditory dis- 

 play, it is not the only one, and in this 

 section we are interested in those auditory 

 displays that do not require speech. The 

 chime of a clock, the whistle of a factory, a 

 fire siren, a police whistle, all are auditory 

 displays. Likewise, any specially designed 

 set of auditory stimuli which transmit in- 

 formation of a particular type are auditory 

 displays. 



Use of Auditory Signals 

 With the single exception of Sonar, audi- 

 tory signals have not been widely used on 

 submarines. Lack of use, however, does not 

 necessarily mean that auditory signals would 

 prove valueless if used correctly, and in 

 situations where they would be most eiSBcient. 

 Some parts of a submarine are practically 

 nothing but display areas. Information of 

 all kinds must be read from meters, special 

 visual displays, radars, and dials, and this 

 information must frequently be used by 

 people who cannot look at the information 

 directly. Thus the information must be 

 transmitted, either by telephone or by some 

 special remote visual display. Information 

 must be transmitted, for example, to torpedo 

 men, to radar operators, and to gunnery 

 men. 



Auditory signals could be used profitably 

 in many of these situations. Whether it is 

 worth while to develop an auditory system. 



or whether one will be feasible at all, depends 

 on the particular circumstances, and on the 

 possible advantages of the auditory display. 

 There are essentially three potential advan- 

 tages in the use of auditory displays, and all 

 three advantages might be realized to some 

 extent in submarine operation. 



Speed of Communication. One of the chief 

 advantages of an auditory signaling system 

 appears in situations where only a limited 

 amount of information is required. The 

 auditory signal can be designed to give just 

 the kind of information required, and thus 

 can give that information in greater quantity 

 and faster. The radio range, for example, 

 is an auditory signal which provides a pilot 

 with only one kind of information — the 

 azimuth position of the plane. The infor- 

 mation, however, is presented to the pilot 

 almost continuously; considering the speed 

 with which the pilot can use the information 

 it is indeed continuous. 



Substitute for Visual Display. In a sense, 

 then, simplified auditory signals can be used 

 as a substitute for speech when only a limited 

 kind of information is needed. Auditory 

 displays are also useful wherever the total 

 amount of information presented to an 

 operator visually is too great. The aircraft 

 is again a good example. The pilot must 

 look at a multitude of visual displays, and 

 it is frequently desirable to present some of 

 that information by ear to relieve the load 

 on his eyes. 



Automatic Transmission of Information. 

 A third type of situation in which auditory 

 signals can be advantageous occurs whenever 

 it is necessary, for some reason or other, to 

 transmit information automatically. 



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