Weddell seal call types made by males and females.

Recordings were made of adult male and female Weddell seals on the ice during the breeding seasons of 1990 and 1997. The recordings were made near Davis, Antarctica in the Vestfold Hills. The vocalisations made with both the mouth and nostrils closed were classified into call types. These call types are also produced by the seals when underwater. The call classifications were based on those described by Thomas, J.A. and Kuechle,, V.B. (1982, J. Acoust. Soc. Amer. 72: 1730-1738) and Pahl, B.C., Terhune, J.M. and Burton, H.R. (1997, Aus. J. Zool. 45: 171-187). Nineteen call types were identified. Of these, males made 18 and females made 15. Trills are only made by males and it is likely that a stepped ascending whistle is only made by females. A roar and mew are also potential male-only call types. The data suggest that the Trill vocalisations can be used to indicate the presence of males. This will be useful when recording underwater where the calling seals cannot be observed directly.

A description of the types of calls made by Weddell Seals is listed below.

SymbolNameDescription
OToneConstant-frequency, predominantly sinusoidal call.
LGrowlConstant-frequency, broad bandwidth, long call.
QWhoopConstant-frequency call with a terminal upsweep.
SSqueakBrief call with constant frequency or rising frequency and an irregular waveform.
WAWhistle AscendingAscending frequency, sinusoidal waveform.
TCTrill Constant-FrequencyNarrow bandwidth trill with a constant-frequency beginning, sinusoidal or frequency-modulated waveform.
TTrillNarrow to broad bandwidth, containing a frequency downsweep, greater than 2 seconds.
WDWhistle DescendingDescending frequency, sinusoidal waveform (less than 2 seconds).
MMewAbruptly descending frequency followed by a long constant-frequency ending.
CChugAbruptly descending frequency followed by a brief constant-frequency ending.
GGuttural Glug (Grunt)Descending-frequency call that was lower than a Chug and had a brief duration.
WAGWhistle Ascending - GruntBrief Ascending Whistle followed by a Guttural Glug (Grunt), the two types alternate in a regular pattern.
KKnockAbrupt, brief-duration broadband sound

1990年与1997年的繁殖季期间，研究人员在南极维斯托尔德丘陵（Vestfold Hills）的戴维斯（Davis）站附近，对成年雌雄威德尔海豹（Weddell seals）开展了冰面录音工作。本次录音将口鼻完全闭合状态下发出的发声行为划分为不同叫声类型，此类叫声类型同样会在海豹水下活动时产生。
叫声分类标准参考了Thomas, J.A.与Kuechle, V.B.（1982，《美国声学学会杂志》（J. Acoust. Soc. Amer.）72卷：1730-1738）以及Pahl, B.C.、Terhune, J.M.与Burton, H.R.（1997，《澳大利亚动物学杂志》（Aus. J. Zool.）45卷：171-187）的相关研究成果。本次研究共识别出19种叫声类型，其中雄性海豹可发出18种，雌性海豹可发出15种。颤音（Trill）仅由雄性海豹发出，而阶梯式上升哨声大概率仅由雌性发出；咆哮声与喵叫声也属于潜在的雄性专属叫声类型。数据表明，颤音发声可作为雄性海豹存在的指示信号，这一结论在水下录音场景中极具实用价值——此时无法直接观察到发出叫声的个体。
下文将对威德尔海豹的各类叫声类型进行详细说明：
| 符号 | 名称 | 描述 |
| --- | --- | --- |
| O | 单音 | 恒定频率、以正弦波为主的叫声。 |
| L | 低吼 | 恒定频率、宽带长时程叫声。 |
| Q | 长鸣 | 带有终端上扫频的恒定频率叫声。 |
| S | 尖啸 | 短时程叫声，频率恒定或呈上升趋势，波形不规则。 |
| WA | 上升哨声 | 频率呈上升趋势的正弦波形叫声。 |
| TC | 恒频颤音 | 起始段为恒定频率的窄带颤音，波形为正弦波或调频波形。 |
| T | 颤音 | 带宽从窄到宽，包含频率下扫频，时长长于2秒。 |
| WD | 下降哨声 | 频率呈下降趋势的正弦波形叫声（时长短于2秒）。 |
| M | 喵叫 | 频率先骤降，随后以长时恒定频率收尾。 |
| C | 咕嘟声 | 频率先骤降，随后以短时恒定频率收尾。 |
| G | 喉音咕嘟（低吼） | 频率低于咕嘟声的短时下降频叫声。 |
| WAG | 哨声-低吼组合 | 短暂上升哨声交替伴随喉音咕嘟，二者呈现规律的交替模式。 |
| K | 叩击声 | 短促、时长短的宽带声响。