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Monday, February 1, 2010

Fev. 01 - Seeing the sounds of the sea‏

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Seeing the sounds of the sea

12:07 01 February 2010

The songs of whales and dolphins can be beautiful to the ear. Now acoustics engineer Mark Fischer has created a way to make them visually pleasing too. What's more, his technique captures more information about the sound than traditional ways of visualising whalesong.

Image 1 of 10
Humpback whale call

This is Fischer's representation of the low-frequency moans and cries of a humpback whale's mating song, with the time axis running anticlockwise.

The sound for this graph was recorded in Hawaii.

Audio: listen to the humpback whale's mating song

(Image: Science Photo Library/AguaSonic Acoustics)
Image 2 of 10
Spectrogram of a minke whale call

To help identify species, marine biologists traditionally plot a spectrogram of an animal's song to represent the sound visually.

This is a graph of the frequency of a minke's cries against time. The raw sound is converted into sinusoidal frequency components via the mathematical process known as the Fourier transform (FT).

FTs are well suited to describing repetitive, continuous noises, but the sounds that whales and dolphins make vary in pitch, volume and length.

FTs are particularly bad at transforming the staccato noises which certain species make. As you can see from this linear spectrogram of a minke whale's "boing" call, the detail gets smeared out and individual pulses cannot be distinguished.

Audio: a Minke whale's "boing" sound

(Image: AguaSonic Acoustics)
Image 3 of 10
Wavelet transform of a minke call

Fischer prefers to use a less common mathematical process known as the wavelet transformation, which represents the sound in terms of short, discrete components known as wavelets.

As this image of the same minke "boing" song shows, these are much better at capturing cetacean song than the sinusoidal waves that the FT is based on: the pulses, represented by the green droplets, are much more obvious.

"FTs are used so much that it has become the only way people can consider a sound. For cetaceans, the sound can be doing lots of other things that are not visible on a spectrogram," says Fischer.

(Image: AguaSonic Acoustics)
Image 4 of 10
Minke whale call

Fischer has taken advantage of the striking appearance of his graphs, selling them as art through his company AguaSonic Acoustics, based in San Francisco.

This is a song from the same species of whale as the previous linear graphs, but plotted circularly.

Fischer sometimes plays around with the appearance of his images: he layers sounds on top of sounds to make flowers, for example, flips the sound inside out and zooms in on certain features, but he says he always retains the original shape of the sound.

This image – which has not been artistically modified in any way – is gnerated from sound recorded by researchers from the Southwest Fisheries Science Center in La Jolla, California.

(Image: Science Photo Library/AguaSonic Acoustics)
Image 5 of 10
Minke whale call

This is the same sound transformed by a different type of wavelet.

There are hundreds of wavelet types that could be used, allowing Fischer to choose the one that will best represent the sound or provide the desired aesthetic effect .

(Image: Science Photo Library/AguaSonic Acoustics)
Image 6 of 10
Atlantic spotted dolphin call

This is an image of sounds made by an Atlantic spotted dolphin, recorded near the Azores.

It both clicks and whistles. The clicks are represented by the straight lines radiating outwards. The sketchy black lines represent whistles, although these are lower in volume, so they could be from other dolphins.

Audio: sounds made by an Atlantic spotted dolphin

(Image: Science Photo Library/
Image 7 of 10
Pseudorca call

This represents the vocalisations of the Pseudorca, or false killer whale, which were recorded by a whale-watching operation off the Azores. Despite the name, these animals are more closely related to dolphins than killer whales.

Their songs contain a wide variety of high-frequency clicks, whistles and cries used for echolocation and communication.

Audio: sounds made by a Pseudorca

In this image, you can see how they click and whistle simultaneously. The clicks are the radial spokes; the whistles are the fuzzy part at the centre of the image.

(Image: Science Photo Library/AguaSonic Acoustics)
Image 8 of 10
White-beaked dolphin clicks

This image conveys the precision with which some species click. These sounds were made by an echolocating white-beaked dolphin clicking at a frequency of around 150,000 hertz.

The sound was recorded in the north Atlantic near Iceland.

Audio: an echolocating white-beaked dolphin

(Image: Science Photo Library/AguaSonic Acoustics)
Image 9 of 10
White-beaked dolphin clicks

This is the same sound as led to the previous image, but Fischer has chosen a different type of wavelet to perform the transform and has played around with the result to produce a floral effect.

He describes it as "artistic licence taken to the extreme". The image is a composite, in which each whorl of the "flower" is formed by an image of a different part of the recording.

He produced the effect by layering the sound clips on top of each other, rotating them, and changing their size.

(Image: Science Photo Library/AguaSonic Acoustics)

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How to Digitally Record/Video a UFO sighting:

Como registar digitalmente ou gravar um vídeo de um avistamento de um UFO:

Stabilize the camera on a tripod. If there is no tripod, then set it on top of a stable, flat surface. If that is not possible lean against a wall to stabilize your body and prevent the camera from filming in a shaky, unsteady manner.

Estabilize a camera com um tripé. Se não tiver um tripé, então coloque-a em cima de uma superfície estável. Se não for possível, então encoste-se a uma parede para estabilizar o corpo e evitar que a camera registe de maneira tremida e instável.

Provide visual reference points for comparison. This includes the horizon, treetops, lampposts, houses, and geographical landmarks (i.e., Horsetooth Reservoir, Mt. Adams, etc.) Provide this in the video whenever is appropriate and doesn’t detract from what your focus is, the UFO.

Forneça pontos visuais de referência para comparação. Isso inclui o horizonte, cimo das árvores, postes de iluminação, pontos de referência geográficos (como o Reservatório de Horsetooth, Mone Adams, etc) Forneça esses pontos no vídeo sempre que for apropriado e não se distraia do que é o seu foco, o UFO/a Nave.

Narrate your videotape. Provide details of the date, time, location, and direction (N,S,E,W) you are looking in. Provide your observations on the weather, including approximate temperature, windspeed, any visible cloud cover or noticeable weather anomalies or events. Narrate on the shape, size, color, movements, approximate altitude of the UFO, etc and what it appears to be doing. Also include any unusual physical, psychological or emotional sensations you might have. Narrate any visual reference points on camera so they correlate with what the viewer will see, and thereby will be better able to understand.

Faça a narração do vídeo. Forneça pormenores sobre a data, hora, local e direcção (Norte, Sul, Este, Oeste) que está a observar. Faça observações sobre as condições atmosféricas, incluindo a temperatura aproximada, velocidade do vento, quantidade de nuvens, anomalias ou acontecimentos meteorológicos evidentes. Descreva a forma, o tamanho, a cor, os movimentos, a altitude aproximada onde se encontra o UFO/nave, etc e o que aparenta estar a fazer. Inclua também quaisquer aspectos pouco habituais de sensações físicas, psicológicas ou emocionais que possa ter. Faça a narração de todos os pontos de referência visual que o espectador irá ver e que, deste modo, será capaz de compreender melhor.

Be persistent and consistent. Return to the scene to videotape and record at this same location. If you have been successful once, the UFO sightings may be occurring in this region regularly, perhaps for specific reasons unknown, and you may be successful again. You may also wish to return to the same location at a different time of day (daylight hours) for better orientation and reference. Film just a minute or two under “normal” circumstances for comparison. Write down what you remember immediately after. As soon as you are done recording the experience/event, immediately write down your impressions, memories, thoughts, emotions, etc. so it is on the record in writing. If there were other witnesses, have them independently record their own impressions, thoughts, etc. Include in this exercise any drawings, sketches, or diagrams. Make sure you date and sign your documentation.

Seja persistente e não contraditório. Volte ao local da cena e registe o mesmo local. Se foi bem sucedido uma vez, pode ser que nessa região ocorram avistamentos de UFOs/naves com regularidade, talvez por razões específicas desconhecidas, e talvez possa ser novamente bem sucedido. Pode também desejar voltar ao mesmo lugar a horas diferentes do dia (durante as horas de luz)para ter uma orientação e referência melhor. Filme apenas um ,inuto ou dois em circunstâncias “normais” para ter um termo de comparação. Escreva tudo o que viu imediatamente após o acontecimento. Logo após ter feito o registo da experiência/acontecimento, escreva imediatamente as impressões, memórias, pensamentos, emoções, etc para que fiquem registadas por escrito. Se houver outras testemunhas, peça-lhes para registar independentemente as suas próprias impressões, pensamentos, etc. Inclua quaisquer desenhos, esbolos, diagramas. Certifique-se que data e assina o seu documento/testemunho.

Always be prepared. Have a digital camera or better yet a video camera with you, charged and ready to go, at all times. Make sure you know how to use your camera (and your cell phone video/photo camera) quickly and properly. These events can occur suddenly, unexpectedly, and often quite randomly, so you will need to be prepared.

Esteja sempre preparado, Tenha sempre uma camera digital, melhor ainda, uma camera vídeo consigo, carregada e pronta a usar sempre que necessário. Certifique-se que sabe como lidar com a sua camera (ou com o seu celular/camera fotográfica) rápida e adequadamente. Esses acontecimentos podem acontecer súbita e inesperadamente e, por vezes, acidentalmente, por isso, necessita estar preparado.

Look up. Be prepared. Report. Share.

Olhe para cima, Esteja preparado, Relate, Partilhe.



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