Anti-masking strategies and communication ranges of polar seal underwater vocalizations

我的研究调查了极地海豹水下发声的产生、传播和接收。来自圣劳伦斯湾的竖琴海豹和来自南极洲的威德尔海豹的水下叫声将被分析，以确定它们是否已经进化到能够克服其他海豹叫声的干扰（掩盖）。两名学生将在南极洲越冬，以确定监测海豹的叫声是否可以索引种群数量，并进一步了解威德尔海豹的发声能力。在最佳条件下，一些水下威德尔海豹的叫声可以在25公里外听到，而另一些只能在100米外听到。竖琴海豹的鸣叫频率每分钟可以超过130次，因此会产生很大的背景噪音。这类似于人类在社交活动中遇到的“鸡尾酒会”效应。我们将确定威德尔海豹是否像竖琴海豹一样，遵循“礼貌规则”并发出叫声，这样它们就不会掩盖邻居的声音。冰裂、波浪、船舶的工业噪音和水下建筑也有可能阻断海豹的声音通信通道。水下呼叫研究使用水听器（水下麦克风）下放到海冰下。因为有这么多的电话重叠，所以没有自动分析的可能性，而且对磁带录音的分析非常耗时。我们将研究自然和人为噪音的可变性，并确定噪音的细微结构对海豹鸣叫行为的影响程度。通过将海豹叫声的生理和行为方面的信息与它们的听力能力和生活史需求联系起来，我们将更好地了解这些极地海豹声音交流的重要性。这项研究的一个实际方面是，它将提供必要的信息，以评估北极破冰船对海豹和其他海洋哺乳动物产生的噪音对环境的潜在影响。

My research investigates the production, transmission and reception of underwater vocalizations of polar seals.  Underwater calls of harp seals from the Gulf of St. Lawrence and Weddell seals from Antarctica will be analyzed to determine if they have evolved to overcome jamming (masking) by other seal calls.  Two students will overwinter in Antarctica to determine if monitoring seal calls can index population numbers and find out more about the sound generation abilities of Weddell seals. Under optimal conditions, some underwater Weddell seal calls can be heard up to 25 km away while others would only travel 100 metres.  Harp seal calling rates can exceed 130 calls per minute thus producing loud backkground noises.  This is similar to the "cocktail party" effect encountered by humans at social functions.  We will determine if Weddell seals, like harp seals, follow the "courtesy rule" and call so that they do not mask a neighbour's vocalizations.  Cracking ice, waves, industrial noises of ships and underwater construction also have the potential to block the acoustic communication channel of seals. Underwater calls are studied using hydrophones (underwater microphones) lowered under the sea ice.  Because so many calls overlap, there are no automated analysis possibilities and the analyses of the tape recordings is very time consuming.  We will examine the variability of both natural and human noises and determine the extent to which the fine structure of the noises will impact the seal calling behaviours.  By relating information on the physical and behavioural aspects of seal calls to their hearing abilities and life history needs, we will gain a better understanding of the importance of sound communication in these polar seals.  A practical aspect of this research is that it will provide information which is necessary to assess the potential environmental impacts of noises generated by ice-breaking ships in the Arctic on seals and other marine mammals.