St Andrew’s Cathedral

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Binaural

Location 1: St Andrew’s Cathedral, Sydney
Time: 6.45pm, Thursday 25th May 2017

The cathedral is a one of the prominent gothic buildings in Sydney and was designed by the famous Victorian architect Edmund Blacket. The walls are constructed of Sydney stone whilst the ceiling is predominantly comprised of stained and painted timber. The highly decorative flooring has been finished with light brown tessellated tile with sections of raised timber underneath the pews within the main part of the nave. The interior is filled with a selection of large and small decorative and symbolic furnishings; statues, plaques and fine wooden fixtures provide not only an aesthetic beauty but also serve to create diffuse surfaces throughout.

St Andrews Main

Figure 1. From the centre of the nave looking toward the pulpit which is located in front of a large glass window. To the right is the cathedral organ, to the left is wooden seating that extends to a stone wall.

Acoustically speaking, the space was judged to be surprisingly noisy. Upon arrival the first thing noticed was the HVAC system which was outputting a steady mid range frequency tone that could be heard above regular conversation. The church was mostly void of worshippers, however due to a service finishing 10-minutes prior, a number of people could be heard talking and exiting through a small chapel to the rear of the main floor space.

The church’s proximity to George St, a major traffic thoroughfare which also happened to have road work activity, meant that despite the nave being closed off via large wooden exterior and glass interior doors, external traffic noise could be heard whilst recording. A 5-minute background noise recording demonstrates the continuous level across octave bands 63Hz to 16kHz.

St Andrew Leq

Figure 2. Measured Leq results show a build up of mid to low frequency energy. This was due mainly to the exterior traffic rumble and HVAC system noise combined with a large non-acoustically isolated interior.

Sine sweep impulse responses were recorded at three different locations, the front, middle and rear of the church with a balloon pop response recorded in the middle of the nave. Figure 3 shows the reverberation time in the range of 1.6 to 2 seconds. Figure 4 demonstrates the frequency spectrum as a function of level.

St Andrews IRs

Screen Shot 2017-06-02 at 9.54.12 pm

Figure 3. Impulse response measurements showing the reverberation time across three separate locations. As expected RT60 is quite long due to the space size and construction.

St Andrews Frequency

Figure 4. Frequency response across three separate locations. An extended response in the low frequencies with a somewhat smooth low to mid range will support the organ program material along with choral material.

The binaural recordings were captured as a succession of 3-minute recordings from the rear, middle and front of the church. Throughout each recording external and interior sound sources could be heard and these ‘spice up’ the overall ambient recording in a way that maintains interest by introducing focal points. Left to right transitions can be heard as a church member walks through the scene or as a motorbike accelerates away in the distance. The effect of proximity is very interesting, not only can sound sources be localized within the left and right field but also at a certain distance away from the recording position. Upon extended listening a feeling of hypnosis begins, possibly due to the effect of concentrated listening to a space with it’s own soundscape that is also part of a larger exterior cityscape that can be heard in the background.

Scene 1 – Rear of the cathedral looking to the altar

Scene 2 – Middle of the cathedral looking to the altar

Scene 3 – Front of the cathedral looking toward the rear

DOWNLOAD ALL SCENES AND IMPULSE RESPONSES

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