tern of a specified sonar dome. In conjunction with 

 a specified sonar transducer enclosed by It, Is a 

 description, often presented graphically, of the 

 dome Insertion loss as a function of the direction 

 of sound transmission relative to the dome's refer- 

 ence axes. (1) 



SONAR PINGER SYSTEM . A system used to precisely 

 determine the distance of equipment above the 

 ocean floor. Two types of systems have been used 

 successfully; one for depths to 6,500 feet and the 

 other for depths to 37,500 feet. The system has 

 been partially successful In positioning under- 

 water cameras at a given distance off the bottom. 

 However, It also can be applied to HANSEN BOTTLE 

 casts, bottom coring operations, etc. 



A transducer, located with the subsurface 

 equipment, emits short bursts of high frequency 

 energy (12 kilocycles) at one-second Intervals. 

 The transmitted pulse travels directly to the sur- 

 face and also is reflected from the bottom. The 

 converted time difference between the direct signal 

 and the reflected signal gives the distance from 

 the transducer to the bottom. Any sonar receiver 

 or cathode-ray tube display can be used to pick up 

 and display the pulses. An echo-sounding recorder 

 is preferred as it gives a graphic picture of the 

 location of the transducer with respect to the 

 bottom and enables maintenance of a constant dis- 

 tance off the bottom. (35) 



SONAR THUMPER SEISMIC SYSTEM . A complete continu- 

 ous seismic profiling system consists of the Sonar 

 Thumper unit. Sonar Recorder, transducer fish, re- 

 ceiving hydrophone, preamplifier if necessary and 

 variable filter. Sonar Thumper units are available 

 from 1000 watt-sec models up to 13000 watt-sec 

 (experimental models). The standard thumper con- 

 sists of a power supply, capacitor bank and trans- 

 ducer. Thumpers are used for marine geological 

 studies and dredging surveys. The power supply 

 output is fed to the capacitor bank which is dis- 

 charged into the transducer producing a precisely 

 repeatable pressure pulse in the water. (30) 



SONIC . Pertaining to the range of audible frequen- 

 cies, sometimes taken as from 0.02kc to 15kc. (7) 



SONIC MARINE ANIMALS. 



Species of fishes, marine 



mammals, and crustaceans which may produce noise 

 of sufficient intensity and frequency to interfere 

 with sound ranging operations and acoustic mines. 

 (15) 



SONOAN . Sonic Noise Analyzer. 



SONOBUOY . The Passive Sonobuoy is a remote "listen- 

 ing" post in the ocean capable of detecting under- 

 sea sounds and relaying them via radio to remote 

 observers. In its primary application, it is used 

 to enable aircraft to probe the sea in search of 

 submarines and, so used, is one of the principal 

 means of ocean surveillance and localization for 

 ASW Targets . It is activated and operates auto- 

 matically after water impact, floats to support 

 the listening hydrophone and keep the antenna well 

 above the water, converts sound signals in the sea 

 to electrical signals for amplification and trans- 

 mission by a self-contained transmitter and antenna 

 to patrol aircraft, supplies its own power. It can 

 be launched from aircraft and can be located from 

 the air in day or night. (30) 



SOOP . Submarine Oceanographic Observation Program 

 (NAVOCEANO) . 



SORTING COEFFICIENT . A coefficient used in describ- 

 ing the distribution of grain sizes in a sample 

 of unconsolidated material. It is defined as 



«md q3 is chat diaaeter having 25Z smaller and 751 

 larger than itself. (11) 



SOOND . 1. A wide waterway between the mainland 

 and an Island, or a wide waterway connecting two 

 sea areas. 



2. A relatively long arm of the sea or 

 ocean forming a channel between an Island and a 

 mainland or connecting two larger bodies, as a sea 

 and the ocean, or two parts of the same body; 

 usually wider and more extensive than a strait. 



3. To measure or ascertain the depth of 

 water as with a SOUNDING LINE. (11) 



4. An oscillation in pressure, stress, 

 particle displacement, particle velocity, etc., 

 in a medium with internal forces (e.g., elastic, 

 viscous) , or the superposition of such propagated 

 oscillations. (1) 



SOOND ABSORPTION . Sound absorption is the change 

 of sound energy into some other form, usually heat, 

 in passing through a medium or striking a surface. 

 (2) 



SOUND BUOY . A buoy equipped with a characteristic 

 sound signal, such as a bell, whistle, etc. (17) 



SOUND CHANNEL . A horizontal layer which is bounded 

 by levels at which the velocity of propagation is 

 greater than at any depth within the layer is known 

 as a sound channel. (4) 



SOUND ENERGY . The sound energy of a given part of 

 a medium is the total energy in this part of the 

 medium minus the energy which would exist in the 

 same part of the medium with no sound waves present. 

 (2) 



SOUND-ENERGY DENSITY . The sound-energy density at 

 a point in a sound field is the sound energy con- 

 tained in a given infinitesimal part of the medium 

 divided by the volume of that part of the medium. 

 (2) 



SOUND-ENERGY FLUX . The sound-energy flux is the 

 average rate of flow of sound energy for one period 

 through any specified area. (2) 



SOUND-ENERGY FLUX DENSITY . See SOUND INTENSITY. 



SOUND FIELD . A sound field is a region containing 

 sound waves. (1) 



SOUNDHEAD (FM) . A cylinder containing the trans- 

 mitting projector and the receiving hydrophone. (5) 



SOUNDING DATUM . The datum (REFERENCE PLANE) to 

 which soundings are referred. (27) 



SOUNDING LINE (LEAD LINE) . 

 sounding lead. (17) 



The line attached to a 



S =\/qi/Q3 where Qi is the diameter which has 75% 



of the cumulative size-frequency (by wt.) distribu- 

 tion smaller than itself and 25% larger than itself. 



SOUND INTENSITY . The sound intensity in a specified 

 direction at a point is the average rate of sound 

 energy transmitted in the specified direction 

 through a unit area normal to this direction at the 

 point considered. (2) 



SOUND- POWER DENSITY . See SOUND INTENSITY. 



SOUND POWER OF A SOURCE . The sound power of a 

 source is the total sound energy radiated by the 

 source per unit of time. (2) 



SOUND PRESSURE . The sound pressure at a point in 

 a medium is the instantaneous pressure at that 

 point in the presence of a sound wave, minus the 

 static pressure at that point. (9) 



SOUND PRESSURE LEVEL . The sound pressure level, in 

 decibels, of a sound is 20 times the logarithm to 

 the base 10 of the ratio of the pressure of this 

 sound to the reference pressure. The reference 

 pressure shall be explicitly stated. (1) 



no 



