Tag: binaural

Røde AI-Micro USB-C phone interface

I am writing this from a field recordist’s point of view, not a podcaster POV. Podcasting seems to be the design intended use case.

There’s nothing more commonplace in the modern urban setting than somebody with earbuds glommed onto the delights within their a smartphone. Pair some binaural in-ear microphones like Soundman OKMIIs with a smartphone and you potentially have an inconspicuous and high performance street field recording rig. You’ll also look like you’re poor and have a cheap phone, because everyone haz bluetooth wireless earbuds, right?

Problem is that smartphones have only mono microphone inputs, or if they are made by Apple none at all. You get cheap USB-C to 3.5mm jack interfaces, but most are mono in, providing the features of the TRRS jack you used to get. I had high hopes for the Røde AI-micro – a little bit dearer than your Chinese noname product, but more functional – offers stereo in. Røde is a well-known manufacturer of microphones, including some very low noise models – the NT2000 is legendary for a very low self-noise of 7dBA.

The Røde AI-Micro worked pretty well as designed, and will be fine for close-up voice, but as a field recorder front end it’s a bust. Compared to an Olympus LS-101 from nearly 20 years ago, it’s noisy. Very noisy.

To test this I injected a -67dBu tone at 150 ohms2 source impedance into the mic input, set to stereo, max gain. The Røde AI-Micro has more max gain than the LS10, so I had to boost the LS10 recording by 8.8dB to make the tone peak the same (to within 1dB). This ensures I am comparing like with like, with a known reference point. Both recordings were made at full gain, and neither was clipping.

These two tracks are 30 seconds of tone, followed by silence3 – the generator turned off but still terminating4 the input with 150Ω.

Røde AI-Micro

Olympus LS-10, boosted by 8.8dB to match tone levels

One listen to these, particularly the second half tells you pretty much all the field recordist needs to know.

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Bawdsey Quay

The sounds of summer at Bawdsey in the school holidays – a motorboat starts up and moves off, and then the passenger ferry arrives from Felixstowe Ferry

Bawdsey looking towards Felixstowe Ferry

Bawdsey Beach

Bawdsey Beach

 

 

Resonant sounds of London’s Museumland

I went to university at Imperial College, in the chi-chi London district of South Kensington.  The area has much to offer the field recordist in terms of resonant public spaces. If you want to avoid the rain or simply enjoy the soundscape  you can take the long pedestrian tunnel under Exhibition Road from the tube station to the museums.

I recently returned to Imperial and went to the Alumni reception who served excellent coffee, gratis. It’s a world away from the machine coffee and plastic cups and ‘coffee whitener’ that fuelled my studies in the Physics department many years ago. The entrance to the College from Exhibition Road is now an enclosed space with lots of glass and hard surfaces, it has an interesting acoustic of its own – I recorded this space from next to the statue of Queen Mary

Footfall Foley wizards will hear the tapping aren’t high heels which most people would associate with the percussive sound but Blakeys on a man’s shoes.

South Kensington has three lovely Victorian museums. Massive galleried spaces over several floors and often a curved vaulting ceiling. These are just made for binaural stereo!

I went to the Science Museum in Exhibition Road, part of a cluster of Victorian Museum buildings. The others are the Victoria and Albert and the Natural History Museum. The latter has an amazing curved atrium and a fine acoustic space.

In the Science Museum on the ground floor near the space exhibition

the next recording is from the Energy exhibition on the second floor, looking over the massive open space to the steam engines on the ground floor

the sharp snap at 00:32 is an art exhibit marked do not touch, which of course everyone touches, resulting in a spark and a slight shock to the curious.

I enjoyed the visit and the incidental soundscapes. It is also good that Britain ended its dalliance with charging for museum entry.

Echoes of South Kensington Station

South Kensington Tube station is the gateway to some of London’s famous museums – the Natural History museum, the Victoria and Albert and the Science Museum. To save people getting wet or wrangling the traffic along Exhibition Road, there is a long pedestrian walkway from the station to the museums.

It has a fabulous acoustic, one that’s enjoyed by small children, buskers and field recordists alike! I went to university at Imperial College and used this tunnel often. Even now, the soundmark takes me back to student times…

Here’s the sound of a busker using the acoustic well, and some kids enjoying the tunnel later on

Robins at Alderman Canal

There is a little nature reserve by the canal near the football ground, an oasis of calm. The water is sluggish with green on top apart from where the water seems to well up from the river bed in these gently roiling clear pools. I don’t think the water makes any sound here, there is some background traffic noise which would mask it.

The nature reserve was improved by the Access to Nature project in 2012. It’s easy to be cynical about some of these projects but this one seems to have worked really well, and there was a lot more birdsong in this part of path by the canal than in the unimproved bits.

Flock of young Jackdaws begging food, Whitchurch, Hampshire

Flock of Jackdaws with young in trees by playing fields and trees by the River Test in Whitchurch. The calls of the young from all around come out in this binaural recording.

Goods Train from Felixstowe, Ipswich St Mary’s

I have some time to do more recording now. Okay, so it’s not hyper-original recording trains but I liked the screech of the wheel flanges as it rounds a fairly gentle bend. I was at the same level as the track across a dip due to the lie of the land

Also a chance to see how this Audioboo thing works… which seems to be pretty well 2018 update – they decided to start charging $9.99 a month. You must be kidding, guys, I may as well pay WordPress £33 a year to be able to get audio facility. There’s no low-end offering.