270 Lecture 14 
50- 
eS 5. 6) 9(-) 8 (---) 
i) 7 (===) \ / 
EO pee SSS. 6 (—) 
a SSE 
EXTERNAL 
NOISE 
ACCELEROMETER 
NUMBERED CURVES CORRESPOND 
TO READINGS FROM BUOYANT-UNIT 
HYDROPHONES LOCATED AS SHOWN 
IN ILLUSTRATION 
x ~ 
ACCELEROMETER 
DECIBEL SPECTRAL LEVEL (dbs) 
{e) 
ae (dbs, relative to gravity) EN EXTERNAL NOISE 
_ SHELL PRESSURE LEVEL 
=e) CONDITIONS OF MEASUREMENT Ss 
VELOCITY — 66 FPS NX 
-40 
DEPTH — 200 FT 
0.1 | 10 100 
FREQUENCY (kc) 
Fig. 14.8. Flow-noise spectrum of buoyant unit when covered with grit. 
6 
50 
@ 40 
2 9 
Sj) 30 F 
W 
> 
ye NUMBERED CURVES CORRESPOND 
zi TO READINGS FROM BUOYANT-UNIT 
a ; HYDROPHONES LOCATED AS SHOWN 
= . ‘ IN ILLUSTRATION 
() 10) ~ 
Ww 
a 
% 10 
) 
WwW 
@ -20 6 
os CONDITIONS OF MEASUREMENT 
fa) \.8 
-30 VELOCITY — 66 FPS Oe 
DEPTH — 200 FT 
100 
10 
FREQUENCY (kc) 
Fig. 14.9, Flow-noise spectrum of buoyant unit with highly polished finish and waxed joints. 
