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THE LONDON SOUND SURVEY BLOG

Occasional posts on subjects like field recording, London sounds past and present, other websites worth looking at, articles in the press, and news of sound-related events.

12 December 2014

The Bird Tree

EACH GROUND-FLOOR maisonette had a back garden with a brick wall round it and a back door. From the walkways and open stairwells you could see over the walls and speculate if the state of any garden matched what you knew about the people.

One was a mess and the family responsible were believed to be a bit simple. Another belonging to an elderly couple had a tiny lawn with two identical shrubs planted in exact spots on either side. The husband was diagnosed with prostate cancer and told us in a tearful moment that his wife was a cold woman. But most of the gardens didn’t hint at any such secrets.

The one on the corner by the play area had a small tree growing perhaps ten feet high. What you could see above the wall from ground level was a ball-like mass of dense leaves resembling a bay tree. Most times of the year loud chirping came from an unseen mob of sparrows inside. Residents called it the Bird Tree.

The Bird Tree was not popular. The sparrows would make a racket from an early hour during the warmer months and sometimes people threw things at the tree to make them shut up. This only worked for a few minutes, then they’d all be at it again.

I’d been to a talk by the BBC nature recordist Chris Watson where he told those present how, as a youngster, he’d miked up the bird table in his parents’ back garden and from a distance recorded what went on. Surely something like that could be done with the Bird Tree to put the listener among the sparrows.

The Bird Tree was a local soundmark. The term is a neologism hatched by the Vancouver-based World Soundscape Project in the 1970s. They defined a soundmark as:

A term derived from ‘landmark’ used in soundscape studies to refer to a community sound which is unique, or possesses qualities which make it specially regarded or noticed by the people in that community. Soundmarks, therefore, are of cultural and historical significance and merit preservation and protection.

Many soundmarks that people notice in their immediate neighbourhoods probably aren’t of much cultural or historical significance at all: a phone junction box that makes a rattling noise, a squealing metal gate, the barking dog in a scrap yard. That doesn’t mean it’s not a useful term.

Vague plans to record inside the Bird Tree came to nothing and its owners eventually cut it down. Either they too had become tired of the sparrows or else were fed up with clearing away all the objects thrown at the tree.

09 December 2014

Down with noise: first impressions of Sennheiser MKH 8020 mics

DURING THE SUMMER I blew . . . I mean, wisely invested a pile of money in a pair of Sennheiser MKH 8020 mics. They’re low-noise (10dBA), high-quality mics and at just three inches long are ideal for headworn use as well placing on each side of a homemade acoustic baffle like the Block.

The DPA 2006C mics I’d been using proved too noisy, even at 16dBA, for very quiet environments such as moorland, marshland, and the insides of buildings when not a lot’s going on.

Scholarly discussions on forums such as Gearslutz concluded that the MKH 8020s are equalised for the free sound field, meaning a hypothetical environment where there’s no sound reflection, but which I understood to approach something like ‘outdoors’, especially those challenging moors and marshes.

The mics are also known to be resilient to humidity and that’s possibly why they’re favoured by some nature recordists, for example the Australian Vicki Powys, and recordings like this one of a thunderstorm in New South Wales helped swing it:


Coldhams Common is a flat expanse in Cambridge consisting of sports pitches and rough patches of grassland. It’s bounded by busy roads on two sides, a railway line to the west and housing to the north. Cambridge’s diminutive airport is to the north-east. This morning I went to the Common and set up the Block baffle with the 8020s clamped to it, each one inside a mic foam and Rycote furry windjammer. Here’s a panoramic view of the recording spot with the middle facing east:

Panoramic view of Coldhams Common, Cambridge


The recording is pretty mundane stuff and no roll-off or other equalising has been applied:

 


The compression used by Soundcloud’s streaming format reduces the dynamic range of what you can hear. With the original 24-bit, 96kHz WAV file the relative loudness of the rumbling traffic is striking. This, of course, is often the case with recordings made using omnidirectional mics. Perhaps it’s also to do with hearing such sounds outside their original context. When we’re in situ our brains may screen out much of the intensity of traffic noise because we’ve become so habituated to it. But the MKH 8020s do seem to have a very powerful low end. There’s some nice detail with the fainter, higher-frequency sounds.

If the mics are equalised for the free field, how might they get on in a diffuse field full of reflecting surfaces? Someone told me that the reverberation times inside Earls Court Exhibition Centre are so long that you can still hear Bob Monkhouse’s voice if you listen carefully enough.

This time the MKH 8020s went on each side of the Block using a stereo bar, the mic clamps that were supplied with them, and a couple of wooden risers made from dowling:

Composite picture showing Sennheiser MKH 8020 mics in use inside Earls Court Exhibition Centre


This recording was made early in the day and you can hear a few different activities going on in the main hall, as well as tube trains passing below the Exhibition Centre:

 


I’m quite happy with that. As with the Coldhams Common recording, the mics could maybe do with being moved forward an inch or two relative to the Block to avoid the sense of something lacking in the middle. But the mics have plenty of oomph and wonderful detail with no really noticeable noise. So far so good.

The question remains as to whether it’s worth spending all that money just to save 6dB of noise over the DPA 2006Cs, which are otherwise very good mics. Perhaps the overall gain should be set lower to begin with and then the mic noise won’t be noticeable. Or, perhaps listeners should be trusted to show some tolerance for a certain (i.e. unknown) level of hissy broadband noise.

The matter of gain or volume levels I first heard raised by the recordist Jez riley French at a talk in Soho a couple of years ago. He made the point that fledgling recordists often produce work where the levels are too high, rather than expecting listeners to adapt to lower volumes. This is a mistake I make from time to time and it’s a good principle to be reminded of: let quiet sounds be quiet.

However, when you disseminate work via the internet the listener has instant control over volume levels, and I bet no other playback context encourages restless fiddling as much as surfing the web does. If something sounds too quiet, even momentarily, the listener can compensate for that with the slightest effort.

Broadband noise is similar to something many older listeners (including me) grew up with: analogue tape hiss. We might tolerate it, although few are probably nostalgic for it. Meanwhile, an ever-growing cohort of listeners have had their expectations raised by digital recording methods.

The relict formats which intrigue them have lower signal-to-noise ratios than modern technology but they also produce warm-sounding forms of distortion which have become signifiers of authenticity or, as with radio futz, immediacy. Broadband noise doesn’t convey either of those qualities and for that reason I prefer to reduce it where I can.

05 December 2014

The Block: making a simple stereo baffle

OVER THE PAST few months I’ve been doing up my flat prior to moving. I don’t really have any great insights to share from that time except: you can do almost anything with bonding plaster (a huge bag of which is only a fiver), everyone should own an SDS+ drill, and those rated tradesmen-type websites are rubbish.

The DIY mindset is contagious and quickly spreads to unrelated tasks, so I took some time out to make a stereo baffle. The idea of a baffle is to help create a convincing stereo image by sticking a sound-absorbing barrier between two mics, typically ones with an omnidirectional pattern. The first person to do this was Alan Blumlein in 1931, and you can read more about him and stereo images in general on this blog post from 2012.

The established design for stereo baffles nowadays is called a Jecklin Disc after its inventor Jürg Jecklin. In its most recent specification, the Disc must be 35cm in diameter and made from a wooden or other solid core, covered on both sides with a sound-absorbent material, typically closed-cell foam. The mics are then positioned on either side of the Disc so there’s a gap of 36cm between them. At least one firm sells Jecklin Discs online but most people seem to make their own. Here’s a photo from the SEA Nature Sound Workshop of Mike Wall demonstrating his own set-up, reproduced here from Flickr under the terms of its Creative Commons licence:

Mike Wall demonstrates his Jecklin Disc setup at the 2013 SEA Nature Sound Workshop


Mike’s Disc array looks to be smaller than the standard spec and the use of two Rycote windshields is a good move for outdoor work. However, I wanted to make something a bit different and began by sawing a £3 wooden chopping board to make a 25cm square:

Sawing a wooden chopping board to make the core of an acoustic baffle


Then I paid Pentonville Rubber to cut me some closed-cell foam tiles to the same dimensions so I could glue layers of them onto the sides of the wooden board, making a block some 17cm thick, roughly the width of a human head. I screwed a camera sliding clamp onto one side and the Block was ready to go.

The Block acoustic baffle in use outdoors


The Block’s sliding clamp means it can be fitted onto the tripod in a few seconds. A photographer’s stone bag fits onto the tripod’s legs and holds the Sound Devices MixPre-D preamp and whatever pocket-sized recorder I’ve got that still works.

You can see that the Block holds the headworn setup I’ve been using since I began compiling the Waterways sound map. This simply consists of a Beyerdynamic headband with two mics attached using plumber’s jubilee clips. A foam and a furry windshield then go on top of each mic.

This way I can use the mics in headworn mode or, if I want to make a longer recording, I can put them on the Block instead. One of the drawbacks of wearing mics on your head is that they’ll pick up any sound you make: breathing, stomach rumbles, and so on. It becomes hard work after about four or five minutes and having drool coming out of your mouth because you daren’t swallow isn’t a good look. Especially if you’re a bloke. And you’re recording in a park. By yourself.

Fortunately, the Block is there to save you from such embarrassment. Also, it lets you monitor what you’re recording over headphones, which you can’t do when you’ve got a mic in its furry pelt covering each ear. I’m not one for monitoring my recordings much, preferring to get home and listen to what’s in the box, but that’s because I’m an amateur.

Talking of parks, here’s a test recording I made using the Block with two DPA 2006C mics in my then-local neighbourhood green space:

 


I think it sounds alright – pretty much the same as having the mics worn on the head.

04 December 2014

Thanks to everyone at the Marlborough and the Social

LAST MONTH I did a couple more play-and-tell evenings under the banner ‘London’s Lost Worlds of Sound’: one at the Marlborough in Brighton and the other at The Social in London’s West End.

It’s always very encouraging to know I’m not the only person who gets excited about old field recordings, so many thanks indeed to everyone who came along. As has now become custom, I took a picture of the audience at the end of each show. Here’s the Brighton contingent:

Audience at the Marlborough pub and theatre in Brighton


. . . and some old and new faces at The Social:

Audience at The Social bar in London


Special thanks to Sarah Angliss for organising things in Brighton and to Carl Gosling of The Social.

I love talking on the subject of old recordings but it’s particularly rewarding getting to talk with people in the audience. Among other things, I learned that scaffolders used to have the habit of quickly warming up scaffolding poles with blowtorches, and this caused the poles to make a hollow droning sound.

If you’d like me to give a talk where you work, study or socialise, then it’d be good to hear from you. Drop me a line through this site’s contact page.

25 October 2014

Brighton and London speaking dates in November

SINCE THE LAST post in August I’ve been busy doing up my flat, meaning rewiring, replastering, tankng a wall, new boiler, painting and so on. The best bit was when the electrician’s apprentice managed to fall through a ceiling. Sometimes people need physical feedback to help learn concepts such as ‘load bearing’. All will be finished by mid-November and after that it’s time to steam ahead with this site as a full-time job.

In the meantime I’ve been persuaded out of the hermetic DIY lifestyle by invitations to give two talks in November under the title London’s Lost Worlds of Sound. In them I’ll be presenting and talking about archival sound recordings of London life, going successively further back in time. Many of the recordings aren’t yet in the Radio Actuality section here so you’d be among the first few people to have heard them again in several decades.

The last Lost Worlds talk I gave was in August at The Social in Little Portland Street near Oxford Circus. Jo Brodie wrote this review of the evening on her Sound stuff blog, which is well worth following.

The first November date is in Brighton on Friday the 7th at the Marlborough Pub & Theatre. This is a beautiful-looking venue and you can read all the details, including ticket prices and booking details, on this page. Many thanks to Sarah Angliss for organising this.

The second date marks a return to The Social on the evening on Monday the 17th. Here’s the relevant event page and abundant thanks to Carl Gosling for having me back there. The Social is a cracking bar, one of the best ones in the West End.

By the way, if you turn up to either of these events you’ll get a free very limited edition London Sound Survey enamelled metal badge as well.