14 Jan 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes from tape: "Time: 10 Zulu." [MLNS notes: low level thumps throughout, with several louder trains interspersed.] Notes from analysis log: Cassette number side up - rewind. Ambient level low - distant ship traffic later in tape. Check out FOG HORN type sound, appears to have regularity, almost every 3 mins (man-made device). Humpback: Neg.; Minke: Pos.; No. Heard: 3?; No Trains: 12+; Need for further analysis: Yes (check grunts 370, slow grunt trains too) 700. Notes: At 59 a thump train, moderate level; at 110- a strong thump train shows, at 180 shows slow strong thumps, short period. At 330 a distant one starts, moments later the strong close one sounds off. At 364 a single strong thump, at 370 a grunt! At 407 weak thumps. At 517 loud strong one, (very good level). At 557 strong slow thump train from a more distant source. At 597 a distant thump train. At 662 the strong thump train sounds. At 700, the slow thump type."
[Notes from analysis log for all tapes in the GRANDTURKS series: "Six half-hour background recording samples on selected days for a period of 53 days... to detect the arrival and departure of the Humpback whales (via sounds) for the season in the Caribbean Sea, Mouchier, Navidad and Silver Banks...There are indications that recordings used a 420Hz Low Pass Filter. Recording equipment used was a Realistic model CTR-19. Cassette recorder operating on 110VAC, Freq 60-10,000Ha.. The Realistic recorder is poor recording frequencies below 60Hz as evidenced by spec sheet and sonograms. There is 120 & 180Hz electrical interference 'splatter' on some tapes. In certain cases when the ambient is low, the gain of the systems are raised hence we have heavy interference masking wanted signals. This could be caused by a fluorescent light fixture near the recording system? I doubt that it is in the hydrophone pre-amp network." See analysis log for more details.] SEAOCEAN