Exploring Antarctica’s acoustics with leading wildlife researchers
It’s well known that Antarctica is absolutely bursting with jaw-dropping sights, but what about the sounds of this otherworldly environment? During your Hondius adventure, you can enjoy interactive workshops led by leading scientists who will show you there’s just as much in Antarctica to amaze the ears as the eyes.
The science of sounds
The main purpose of our acoustics workshop is to record and analyze the sounds made by Antarctic animals, both above the waves and below them. The animals we may record include whales, seals, penguins, and seabirds. With whales, for example, we can use hydrophones (underwater microphones) that we lower into the water. We can also use our Zodiac boats to get closer to the whales and deploy one or two hydrophones over the side. Our hydrophone holders can even hold underwater video cameras to capture the animals if water clarity and local conditions permit.
Various means of recording below and above the water
We can record underwater sounds using special amplifiers coupled to analogue-to-digital converters, recording the digital signals directly to a laptop. The recording system can cover the low frequencies used by large baleen whales, like fin and humpback whales, as well as the ultrasonic clicks used by killer whales and dolphins. We can hear the ultrasonic clicks of dolphins by playing them through a special detector that converts high frequency signals to our hearing range. For recording video signals as files on a laptop (Mac or Windows), we use video recorder software like Elgato Video Capture. The same setup can be used to record the underwater sounds of seals, if we’re lucky. We can also record the sounds of penguins and seabirds using a handheld sound recorder that stores these sounds digitally. Video cameras can also be used to record vocalizations and visual images for later analysis.
Analyzing Antarctic sounds
To analyze our sound files, we use free analysis software like Audacity and R (for those who would like to design their own analysis programs). Of interest to us is the frequency structure of our recorded sounds (or calls), the relative amplitude (loudness) of calls, the time duration of calls, and the call rate. If we use two hydrophones attached to a rod, we can get an indication of the bearing to the whale, either horizontally (to the right or left of our setup) or vertically (toward the surface or deeper). To analyze video files, we use iMovie (Mac) or Windows Movie Maker. We can speed up or slow down the video recordings or add our audio recordings to the video soundtrack. If the sounds come from a dolphin, we can slow these down to our hearing range with the sound analysis software or use an ultrasonic detector to hear a facsimile of the sounds in real time. These detector sounds can be clipped to the corresponding video recording, if available.