What bird is this?

The other week my Twitter friend Cindy Bahl sent me a recording of this bird, which she’d heard in Kansas City, Missouri earlier in June. It sounds rather like someone doing something to a piece of sheet metal with a machine that’s painfully in need of lubrication. Can anyone identify the bird?

Here it is, with some background sounds edited out.

Lately I’ve been listening to slowed-down versions of birdsong and bird calls. The result is sometimes much more complex and musical than one would expect. Skylarks, for example, structure their song in a way that sounds very similar to human music. An unpromising chirp can turn into something startlingly beautiful.

So of course, I wanted to try that with this recording and see what I got. Here it is again, slowed down in one-octave steps. (To avoid very long almost-silences, I’ve cut more of the gap between calls each time. So there’ll be inconsistencies if you try to follow what the other birds are doing.)

(The downloadable versions are MP3s, with a total size of 2.4 MB.)

There’s certainly added complexity. The bird is singing a fast and consistent sequence of notes. In the final version, three octaves below their original pitch, they sound a bit as though they’re being played on a pipe organ.

At a sixteenth of the original speed, this becomes a sequence of foghorn or ship’s hooter notes. But it also becomes very murky to listen to, so I haven’t included it.

As for beauty, maybe that’s in the ear of the beholder . . .

If you’ve any idea what the bird is, please leave a comment below.

Protected: 20 minutes of birdsong (draft preview)

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Morning chorus

I’m not a morning person at all. In fact I’m so much a night person that at this time of year, it’s not unusual for me to be awake when the birds start singing. At present they’re doing this not long after 3 am.

This recording is from around 4:15 am a couple of nights ago. I had the window open because of the hot weather, and realised that not only had the birds started up but there was next to no traffic or wind.

So I put the recorder on the windowsill and let it record for about 25 minutes.

I was also getting ready for bed during the recording, so there were quite a few audible interruptions. This track is one of the longer uninterrupted sections, after some filtering and noise reduction.

You’ll notice seagulls, but don’t be fooled—I live well away from the sea. I live fairly near to some reservoirs, though, and I think those might be responsible for there having been gulls in the area for as long as I remember.

Note: The download button in the player will give you a 28 MB, CD-quality WAV file. If that’s too big, try this MP3 version (5MB, 256kbps). And if that’s too big, ask and I’ll maybe make a lower quality one.

Singing in the rain

Not me! The birds.

Last year I decided I ought to buy myself an audio recorder, and so I extravagantly did: a Tascam DR-07X, if you’re interested in that sort of thing.

This of course led to downloading the popular audio editor Audacity, and to experimenting with it to see what I could do.

The rain

Here’s the result of such an experiment. A couple of weeks ago we had some nice heavy rain, which was making a nice satisfying noise, so I stood at the back door for a while trying to get a nice satisfying recording of it. What I got was a mixture of rain (wanted), birds singing as though oblivious to the rain (wanted), button presses and wind dropouts (not wanted), and a motorbike (definitely not wanted).

So, here are two versions of the recording.

In the first, all I’ve done is increase the sound level.

In the second, I’ve done my best to remove the extraneous noises while keeping the birdsong intact and not affecting the sound of the rain more than necessary. I think I did better with the first two of these than the third. Have a listen, and see what you think.

I’m particularly pleased with the successful removal of the motorbike.

(The download button in the player will give you a 22 MB CD-quality file of whichever track is currently playing. If you’d prefer something smaller, here are MP3 versions of the original and edited track. They’re 4.1 MB each.)

The editing

The technique I used was as follows:

  • First split the track into two: a high-frequency one containing the birds and the upper end of the rain, and a low-frequency one containing the motorbike and the lower end of the rain.
  • Where the motorbike appears, carefully listen to the rain, and identify a nearby section that sounds similar but has no motorbike.
  • In the lower track only, completely delete the section with the motorbike. Replace it with audio from the motorbikeless section, with a short crossfade at either end.
  • Recombine the two tracks into one.
  • Apply equalisation, to restore the correct frequency balance.

The result is a track in which the birdsong has been left (almost) untouched, the motorbike is gone, but the upper and lower frequencies in the rain are sometimes from entirely different raindrops.

Making the split

To split the sound, I used a high-pass filter on one copy of the original track and a low-pass filter on another, both with the same cutoff frequency. But what frequency?

I could see from a spectrogram view of the original that most of the birdsong was above 2000 Hz, and most of the motorbike sound was below 500 Hz. The sharpness of the filter cut-off is specified in dB per octave, and these pitches are two octaves apart. So I made the split midway, at 1000 Hz: an octave below the birdsong and an octave above the motorbike. This should mean the birdsong and motorbike were equally well removed by the two filters.

(To imagine 1000 Hz, imagine the Greenwich Time Signal pips: that’s their frequency.)

On listening to check, I couldn’t hear any birdsong at all in the lower track and I at least couldn’t identify any motorbike sound in the upper one, as intended.

Would it work?

I was most unsure whether “fake rain” made up of high frequencies from one lot of rain and low frequencies from another would still sound realistic. In particular, would the process affect the stereo spread, built up from the locations of thousands of individual drops? And might the result sound like an unnatural mixture of some muffled drops and some overly bright ones?

In the event, I think it did work, but I can’t quite decide whether the stereo of the original is more convincing.

Equalisation

The equalisation step is needed because the splitting and recombining process is imperfect. Frequencies close to the split end up louder than they should be, resulting in an obviously “boxy” sound. I did this part by ear, and the reconstituted rain definitely doesn’t sound the same as the original rain. However, I reached a point where I preferred the sound to that of the original, so I stopped there rather than try to get a perfect match.

Really I think I should do the maths to work out the theoretically correct equalisation, and use that as a starting point.

On the other hand, the rain still sounds heavy and very wet, which it was, and the birds still sound determined to keep singing, which they were. And I hope you’ll enjoy listening.

In the bank

Some of you will know that my mother died not so long ago. This brings with it a variety of admin tasks, which you go through as best you can. These can be tiring, but also, it turns out, often bring you into contact with surprisingly friendly and supportive people.

And one effect of bereavement seems to be that you find yourself wanting to talk a lot. Someone asks how you are and next thing, you’ve told them some memories of the person who’s died, or how the death came about, or that no really you’re managing fine because the way you’re feeling is nothing like you imagined it would be beforehand . . . Or at least, that’s how it’s been for me. It’s a different experience for every bereaved person, I think.

Anyway that’s not really what I’m wanting to write about. It’s background. I’m writing about the assumptions that are often made about “old” people and computers.

I had to inform my mother’s bank of the death. This entailed taking a death certificate in and filling in a straightforward form, and I’d made an appointment to do this. The bank had an open area with seats and tables, where people could do banking stuff in an informal atmosphere, and a separate mini-office which could be used if more privacy was wanted. I wanted more privacy, but was waiting in the open area for my appointment.

Also waiting was an oldish lady with a walking stick. I was in a talkative mood, we got talking and I mentioned what I was there for. She said “Oh, I am sorry. How old was your mum?” “89,” I said. “But it wasn’t unexpected. She’d been ill a long time, and . . . ”

“Oh.” she answered. “Well I’m 89!” so I hurriedly reassured her that she was in far better health than my mother had been and that I was sure she’d got years and years ahead of her . . .

At this point I was rescued from digging myself into any deeper hole by the arrival of one of the bank staff. I sat myself further away so as to let their conversation be private. But I couldn’t help hearing most of it anyway. So much for privacy in open-plan banks.

The man from the bank asked how he could help her. “Well,” she said, “I’ve accidentally locked myself out of my online banking. I entered my Face Time password by mistake instead of the banking one, and now it won’t let me in . . . ” From the subsequent conversation it was clear that she used online banking all the time, and that she was perfectly comfortable with it except for the minor issue of it being difficult to remember a different password for everything without occasionally getting one wrong.

Contrast that with the stereotype of someone her age: confused, terrified of computers, totally hopeless when put in front of one, needing to be led by the hand through the simplest of operations . . .

In fact there’s even a similar stereotype about over-50s. Well I’m one of those. In fact, if the calendar is to be believed, I’m 57. (Very odd. I still think I’m 33. Possibly a little older, but definitely no more than 36.) We’re supposed to be unable to use a computer or understand the simplest of jargon . . .

Well. By the time I left university in 1984, I had programmed in Fortran, Algol, Basic, and 6502 assembler. (The 6502 was one of the early microprocessors.) The first computer I had of my own was an Amstrad PCW8256, but I upgraded the memory to a whopping 512 kB. Half a megabyte!

You could use one of these with the software it came with, if you just wanted to use it as a word processor. But I wanted to do more with it. And if you wanted to use your “home computer” for anything more interesting, you had to program it yourself. None of this ridiculous searching around for apps that don’t do quite what you want: write something yourself that did exactly what you wanted, or possibly read computer magazines and laboriously type out somebody else’s program then correct all the typos that were stopping it running and giving you error messages . . .

I wrote BASIC programs for a while, but I knew that was inefficient. BASIC was an interpreter: that is, the computer had to translate the instructions as it went, turning instructions like IF N>10 THEN GOTO 320 into sequences of hexadecimal digits (or really, sequences of 1’s and 0’s, read in blocks of 8 and effectively fed straight into the electronics) which the computer’s processor could execute.

I didn’t like being limited to BASIC. I wanted to program in machine code (the 1’s and 0’s). This is usually done using a program called an assembler: this lets you write short instructions meaning things like “increase the value of register A by 1” or “load the value stored at the following memory location into register B”, which it then translates into the 1’s and 0’s for you. The program you then run is the translated version.

For some reason presumably known to Amstrad, the assembler that came with the computer didn’t have any documentation and I couldn’t get it to work. (It was also, I later found out, written for the wrong processor: it was for the 8080 processor, whereas the computer contained the more advanced Z80.)

So, what did I do? Give up because our generation didn’t understand computers? No, I wrote my own assembler. First in BASIC, but then—once it was working—in machine code. I used the BASIC version to assemble the first machine code version, and thereafter, each machine code version to assemble the next. And you know what? The machine code program ran at 130 times the speed of the BASIC one! I was stunned. It suddenly did in about two seconds what had previously taken it well over four minutes.

What I find sad is that since then, computers have got faster too quickly: rather than run more and more efficient and reliable software, they run more and more unwieldy and bug-ridden software which grinds to a halt on all but the most up-to-date machines. They get away with it simply because processors have got ridiculously fast and storage has got ridiculously big.

I also find it sad that at some point, schools switched from teaching children coding (albeit in BASIC because it was simple), with the excitement of making their own programs do their own things, to teaching them the tedious “skill” of understanding what all the badly-named menu options in some piece of commercial software are for. To my mind that’s not understanding computers—it’s understanding office work. And it’s all in the manual anyway, if the manual’s any good.

So there you go. I think “my generation” understood computers rather well, and I think the 89-year-old in the bank understood hers well enough for all the things she wanted to do on it. She just found remembering which password was for what a bit tricky. And who hasn’t had that problem?

Don’t make assumptions based on age!