The Listening to Birds Blog

Song Thrush by Nigel Pye //

January 16, 2008

The sound microscope and the whippoorwill effect

Filed under: Perception — Tags: , , , , , — Andrew Whitehouse @ 6:16 pm

Recently I was sent a CD released by Smithsonian Folkways called The Birds World of Song: Listening through a Sound Microscope to Birds around a Maryland Farmhouse. The CD was first released in 1961 and made by Hudson and Sandra Ansley. It’s a fascinating listen and you can hear brief samples and purchase the CD here.

So what is a ‘sound microscope’ and what sort of effects does using one have on how we hear birds? According to the sleeve notes by Hudson Ansley,

A two speed tape recorder is a sound microscope. By recording at high speed and playing back at half speed, the effect is to magnify the song, or extend it over twice the length of tape.

The microscope magnifies not in size or volume but in time. By slowing down the recordings more detail can be discerned by human ears. The Ansleys used this technique to write bird song in musical notation and to compare different songs in more detail than would be possible with recordings made at a normal speed. Perhaps most significantly, they used the sound microscope to try to understand how birds sound to each other. Could birds hear the detail that the sound microscope revealed?

The first two tracks on the record consist of recordings made in March and June, with most of the songs slowed down. The sounds are strangely disorienting at first, and are rather reminiscent of the whistles of the Clangers, for those that remember them. These are followed by four tracks of analysis by Hudson Ansley, in which the elements of each song are examined and compared with others. He argues that we are unable to take in the bursts of sound in bird song because our cochlea is different to a bird’s. “The twitter we hear as bird song is sheer distortion,” he claims, but by slowing down the sound we are better able to deal with the complexity of sound that reaches our ears.

The final track, ‘Mockingbird’, introduces a discussion of how birds hear other birds. Northern mockingbirds are able to mimic all the other birds in the area with great accuracy. One of these local birds is the whippoorwill, whose song sounds to us rather like its three-note onomatapoeic name. But when the song of the whippoorwill is slowed down, it becomes clear that the song consists of five rather than three notes. So how many notes does the mockingbird sing when it mimics a whippoorwill? As the sound microscope reveals, the mockingbird sings five notes too. Ansley argues that this shows that the mockingbird hears the notes that we are unable to discern – what Ansley terms ‘the whippoorwill effect’. The sound microscope thus furnishes us with an experience of sound akin to a bird’s.

In listening to this recording, I’m reminded of the artist Marcus Coates‘ piece ‘Dawn Chorus’, in which recordings of birds are slowed down to a speed that humans can more readily imitate. He then asked singers to sing these slowed down versions and then speeded them back up so that they sounded like the original bird. You can see an example of this here, where there’s also a clip of the slow singing. Coates is interested in human-animal relations and in ‘Dawn Chorus’ he encourages us to think about these relations and about what it is to be human. This harks back to Hudson Ansley’s sleeve notes to The Bird’s World of Song in which he argues,

We decline to hew to a line that separates man from other animals, nor do we see any reason to draw a qualitative distinction between bird song and man-made music.

I made my own ‘sound microscope’ using the free sound editing programme Audacity and used it to listen to some crossbills I recorded last week. The first recording is at normal speed and includes one crossbill giving an excitement call (the low churping that sounds a bit like a blackbird) and another singing (including the repeated ‘tee-chur’ phrase that sounds like, and probably is, mimicry of a great tit).

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The second recording is the same recording slowed down to -75%. The great tit mimicry now sounds rather like a cuckoo.

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The work of both Coates and the Ansleys suggests that our experience of life is not totally contrasting with birds but is somewhat slower.

Thanks to Julian for sending me the CD.

January 14, 2008

The sound of spring

Filed under: Perception,Uncategorized — Tags: , — Andrew Whitehouse @ 3:49 pm

First of all, a happy New Year to all readers. It should be a very busy 2008 on the Listening to Birds project.

We’re still enveloped in the depths of winter here in the northeast of Scotland but the days are beginning to draw out and the first signs, and sounds, of spring are in the air. Over Christmastime I was down in the rather mild English Midlands and the relatively warm weather was encouraging a few birds to sing. During the autumn and early winter the only birds I’d heard singing here in Aberdeen were robins and wrens but down south goldcrests, mistle thrushes and dunnocks were also tempted into song.

But it’s not just the sound of birds singing that marks the coming of spring. Once or twice, even in the grip of some fierce winter storms, I’ve heard the brief burst of an oystercatcher over town. We see them along the coast here all winter, but as spring gets closer they start prospecting nest sites further inland and can be heard overhead, often at night-time. And for some time now the herring gulls that nest on the rooves below my flat have been returning to their nest sites periodically and calling to one another with that familiar seaside cry. I look forward to being regularly awoken as the days lengthen. Here’s one I recorded last week, with the thrum of Aberdeen harbour in the background.

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Some birds just seem to sound summery whatever the season. Here’s a flock of goldfinches I recored twittering above the traffic in Torry in December.

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The lightness of their call somehow seems to evoke a feeling of sunny days and flower-filled meadows, even when the surroundings are anything but.

Hearing these sounds appear as the birds’ lives journey through their annual cycle is to me less about phenology, the scientific study of these first appearances, and more about the feeling those sounds give of life progressing, both for birds and for humans.

If you’d like to tell me about your own sounds of spring then you can post your experience through the contribute section of the website.

The University of Aberdeen