Spectrograms of the varied acoustics sources recorded by the Bransfield and Scotia Sea hydrophones.

<p>Panel (A) shows record of emergent, broadband, icequake acoustic arrival; (B) shows record of impulsive, short duration icequake signal, indicating that icequake may be closer to source, experiencing less attenuation than emergent record; (C) shows fundamental and harmonic overtones of iceberg tremor; (D) shows Antarctic blue whale vocalization; (E) is an earthquake (T-phase) signal packet with broadband airgun arrivals in background; and (F) is noise from a ship, generated by cavitation from the propeller. The sound energy level is roughly equivalent for all sources; however, each varies in prevalence through the year.