Very pleased to have been instrumental in organising and hosting this forthcoming event representing JAMES regional gang and the Audio Engineering Society of Scotland's joint Scotland conference.
Wemyss Bay Caves Auralization Project
OTSF 3rd International Archaeoacoustics Conference Proposal
Nicholas Green MSc
Perth College, University of the Highlands and Islands
Wemyss caves found on the North shore of the Firth of the river Forth, Scotland represent the most Southerly boundary of ‘Pictland’ or ‘Pictavia’ and features the largest concentration of class 1, early Pictish/Bronze Age cave carvings known. The complex of caves, created by tidal action between 8,000 and 5,000 years ago has been a site in use for centuries and were probably inhabited by cave dwelling Bronze Age people of Scotland.
The University of St Andrews archaeology department commissioned a recent 3-D Laser mapping project of the site (http://www.4dwemysscaves.org/) and in early 2016 discussions around auralization and an archaeoacoutic study were suggested as a means of helping to complete a fuller story of this significant site. The project, although still in its editing and preparation stages was carried out in November of 2016.
The fieldwork proved challenging from an auditory analysis perspective due to some of the caves proximity to the shoreline and the tidal noise that accompanies and in many ways defines the auditory characteristic of the site. However using a complimentary series of field recording analysis techniques some very useful and representative recordings were made. All of the caves, four that are of use in this study were sampled from multiple source points using both full range sine sweep techniques and a more ‘guerrilla’ technique, that of bursting a balloon and recording the result on a mobile recording device. This later technique whilst being more limited in its frequency range does yield instant impressions of the acoustic signature of each cave.
It is proposed that an overview of the auralization project of this significant site be presented at the forthcoming Archaeoacoutics III conference. Drawing conclusions of how our earlier ancestors learned about acoustics in their environment and this might have been applied to later Medieval architecture.
So far the content added to this journal is all from archives, field and research notes. Some of it coherent some not so and usually a process of filtering thoughts and seeing what sticks.
To date my research has mainly centred around the methodology of recording both hi-fi and lo-fi impulse responses taken from historic locations, mostly around Scotland. Boasting some fantastic castles, abbeys and cathedrals from the medieval period the continued challenge is to find ever more interesting sites in which to record and older sites from pre-antiquity. The Picts become an inviting challenge, spanning as they did the pre-Christian, Bronze Age eras, through the Roman occupation and subsequent documenting and still the best documentary evidence for our Scottish ancestors, to their integration in Christianity and influence right into the Medieval period. They do present a challenge from the point of view that there is very little architecture that they left behind in which to analyse the acoustic spaces they used and inhabited.
Earlier Scottish archaeology and the neolithic people of Scotland also present some architectural challenges, however they have left their mark and most strikingly on the Orkney Isles. Colleagues from the University of York recorded the acoustic characteristics of Maes Howe the famed neolithic dwelling on Orkney, however recent archaeological digs taking place now at the Ness of Brodgar present some real opportunities. Although little more than layers of stone foundations representing a multi-use site on the same space over millenia, acoustic models can be 'digitally built' representing the sound of the spaces as imagined by artistic renderings of sites architecture.
The site also has evidence of the ritualistic, mass slaughter of cattle and feasting and pilgrimage taking place, as a sound designer this presents a creative challenge and could even evolve into a filed of archaeoacoustics little explored to date: the design of soundscapes as our ancestors may have experienced their environment.
This is a future project I hope to undertake collaborating with others within and out the wider UHI network.
Re-imagining Space Field Recording #3 - Perth City Hall
Having exchanged several emails PKDC gave permission to access the old Perth City Hall. Having stood empty for nearly 8 years, as the cities premier concert hall and civic heart for a hundred years it seemed an obvious choice to take IR recordings to de-convolve into reverbs. Having arranged to meet Jonathan from the city council he gave me access through the side door to the hall and left me to get on with the fieldwork, leaving instruction the pull the door locked when finished.
Being in such a large building having been built for large crowds and as the civic centre to the city, it felt eerie being left alone. My research collaborator Paul was not available at the time of this site visit. I also have a personal connection to the hall having graduated here as an undergrad student many years previous!
The main and lesser hall had a feeling of having just been vacated and minor work by labourers a few years earlier and the odd pile of pigeon dung here and there the only evidence of living beings having been there at all. There were odd bits and pieces of debris laying around, partially removed fixtures and an accumulation of dust over everything.
Entering the Lesser Hall at the back of the main hall I was immediately impressed by how well preserved the 1911 Edwardian, blue cake icing decor was and immediately struck by the fabulous long, linear reverb. I spent a while enjoying having the space to myself, uninhibited I recorded the IR balloon pops and indulged in some gregorian style vocalisations. Plenty of photographs, some video and stereoscopic photographic records were taken. As with other rectangular buildings I have sampled I positioned myself in front of the small stage (cordoned off by building engineers) to pop the balloon, with the recording equipment positioned approximately one third into the hall from the rear wall. Despite being a large rectangular shaped room, the reverberant quality of the room has a really nice, smooth quality with little audible build up of resonant frequencies.
Moving into the main hall, an even larger, multi-tiered, balconied room with a large stage at one end the ceiling in the main hall is curved. The stage still has it's tiered seating at the sides and the pipe organ elevated area at the rear, the organ having been removed for a new home in Australia. Having a lot more large feature fittings, the main hall seemed to have little reverb despite it's size. However upon recording the first impulse responses the room revealed a really interesting, if not wholly pleasant reverb with a pronounced flutter echo. Due to the fittings the rooms reverb is much shorter than the lesser hall having more surface area at odd angles to break up and diffuse the reverb tail. The flutter echo is the result of any sound building up under the balcony and bouncing around in the space contained around the edges of the room.
IR recordings were taken from a third into the room from the rear wall for the recording equipment and a third in from the front of the stage. Second recordings were taken with the recording equipment in the same position and the IR balloon pop on the stage, the stage having some 6 feet elevation above the floor. It's worth pointing out that the only remaining seats are in the balcony. A final recording was taken, this time with the recording equipment positioned in the centre of the rear balcony, the IR position from the stage. Again much metadata was taken in the main hall. I completed the field recording trip having a good wonder around the building. It is hoped that a further site visit can be set up and that Paul and I may have the opportunity to take further readings and data gathering.
Whilst not a building of ancient historic significance the fact that the building may never be used for it's original purpose or be demolished in the future this is a significant field study with relevance in the fields of archaeoacoustics, digital heritage and acoustic ecology.
Many thanks to PKDC and particularly Jonathan James.
Perth Archaeology Month, Presentation and performance, Perth Museum
Introductions and abstract.
Introduce archaeoacoustics, background, multi-disciplinary aspect.
OTSF conference, Malta and Turkey.
Introduce field work with examples.
Explain the principles of IR and convolution.
DIY context, the Gerilla Impulse using available portable equipment.
Introduce audio examples.
Schedule: 4th June, 10 - 5
10 - 2 presentation rehearsal and tech set up
2 - 5 musicians
Laptop with all IRs loaded
Visuals for performance
Guitar and stand
5 mic's & DI, mic stands, cables, interface cables laptop and to go into museum system
Mac thunderbolt to VGA adaptor
Paul guitar - Kinoull Aisle
Syann vocal - Lesser Hall
Aileen and Ronnie vocal & percussion - Scone Chapel & City Hall
Pete - Errol Brickworks
Ensemble - blend of reverbs
8/4/2015, Errol, Carse of Gowrie
Meet Paul in the square in Errol at 2pm our mission today to record the acoustic signature of the kilns at Errol Brickworks, now a Mackies Potato crisp factory. The kilns stand as a monument to the prior industry, having only previously seen archive photographs of the kilns I had high expectations for the acoustic quality to be found within.
Paul had organised our visit with the owner, upon arriving the kilns were obvious, 2 side by side, squat dome shaped structures as wide as they are high. The internal diameter after analysis was found to be 5.5m by 6.5 m in height at the highest point of the dome and floor proving to be several feet lower than the ground outside. We were able to access only one of the kilns on the day of our arrival, this kiln having no door the other locked. A repeat visit would be worth while to measure the other kiln for comparison purposes.
Paul brought along his guitar, so along with the sine sweep and balloon burst impulse response (IR) recordings Paul performed a live improv inspired by the space and the moment, having at one point to respond to the sound of air brakes and the not too distant sound of a lorry leaving the factory 500m's away!
The kiln when entered for the first time was acoustically disappointing, appearing to have very little natural reverberation decay. The space proved more interesting after walking around and listening for a while, at one point I had clambered over the rubble strewn floor (mostly bricks and brick dust) further towards the opposite wall from the entrance. The sound of Paul's footsteps near the entrance approached the quality of the whispering gallery in the dome of St Paul's cathedral in London, albeit on a small physical scale, a distinct delay in what I was seeing and then the sound I heard being transmitted in stereo behind me along the inside edge of the wall. In analysis of the IR this manifested itself as a short but very pronounced pre-delay, the total reverb decay time in the kiln is approximately 0.87 seconds.
Post script: on the way home from the Errol Brickworks field recording session, I opportunistically stopped at the roadside just outside Abernyte, vaulted a fence and Meade my way to a disused grain silo spotted on the way to Errol. Having swiftly obtained an IR recording using a balloon I had 2 Field recorded IR's in the bag in one day. The grain silo, 20m's tall, cylindrical and made of concrete exhibited a reverberation decay time of 8.5 seconds long?
Kinoull Aisle, field recording 1/4/15
After picking up the keys and some vital site information from David and Andrew at the Heritage trust offices in Perth, Paul and I made our way to Kinoull Aisle to conduct some field recordings. Kinoull Aisle has had a church on the site since the mid 14th century. The Aisle contains a large carved stone monument to the 1st Earl of Kinoull and measures approximately 4.5m by 5.5m with an approximate height of 6.5m. Upon entering the Aisle Paul and I immediately assessed the quality of the reverb, the height helping to create a rich but smooth reverb. A lot of the potential problem resonant frequencies were diffused quite effectively by the recessed shuttered windows and door and the monument itself.
The purpose of our field recording trip was to record a historic location's reverb in Perth to be used in a presentation and performance in June 2015 Perth Archaeology Festival. The opportunity to record at Kinoull Aisle would afford Paul the chance to further research the methods of DIY ethics and practice and my own field of research, archaeoacoustics and the collecting of the reverberant chacteristics in a series of digital data including audio recording.
As part of our field work analysis I had suggested to Paul that he bring his guitar which, recorded live on location would make a good comparison with the digitally processed reverbs gathered on site. My intention was to try recording Hi Fi quality reverb files using reference class equipment whilst also gathering Lo Fi recordings with 2 different portable recorders. Metadata in the form of visual spectrograms and numerical decay time over frequency tables were also taken, these achieved thanks to an iPad mini and 2 freely available apps. In keeping with this DIY ethic the Lo Fi recordings could have also been achieved utilising mobile technology and easily available mobile phone or tablet microphones.
Photographic recordings from the site are also an essential element of the practice of recording impulse responses these help contextualise the recording environment. Many photographs were taken on site both inside and out of the Aisle, along with video footage.
The Lo Fi portable recorders of choice were a Marantz PM661 and an Alesis Palmtrack, unfortunately upon uploading files from the Palmtrack later the same day they proved to be corrupt, a new HD card formatting error. In order to successfully capture the reverb characteristic of a space eventually an impulse response recording is required. This is essentially a short loud burst of broadband sound introduced into the space, clapping your heads is effective if limited containing very little low and high frequencies to be useful. A sound of a controlled explosion is what is ideally required, a balloon being burst or similarly a starters pistol being fired, both providing a useful amount of broadband energy. Due to the public nature of many of the historic sites sampled to date the starters pistol method was ruled out for obvious ethical issues. Successful recordings of the balloon burst were made with the Marantz recorder.
The Marantz was also left running in order to capture Paul's live improv playing acoustic guitar. Inspired by the environment Paul improvised an on the spot performance for 8 minutes or so.
Summary of equipment used:
For sine sweep recording - Apple MacBook running Impulse Utility software, MM1 reference microphone, Bose Soundlink mini loudspeaker unit, Presonus USB interface.
Impulse response recording - balloon burst, Alesis Palmtrack and Marantz PMD661 portable audio recorders.
Post production - Apple's Logic Pro Space Designer convolution reverb software.
All audio recorded and processed at 48KHz 24bit.
The rambling thoughts and musings of an audio engineer/sound designer turned archaeoacoustician