Page 32 - Winter2018

Archaeoacoustics
evidence. Lubman recounts the study (Personal Communi- cation, 2018):
“The unusual sound at the shrine of St. Werburgh, at Chester Cathedral (see chestercathedral.com) in western England, was brought to my attention in 2000 by the English architect Peter Howell and the architectural historian Julia Ionides of the Dog Rose Trust, a registered English charity. Peter and I visited the Shrine at Chester in July 2003. The shrine had been constructed, moved, rebuilt, damaged, and repaired, with these architectural changes traceable historically. I con- ducted an acoustical experiment to test functional questions about the role of sound in the petitioning process, the prayer requests a shrine visitor makes to the religious figure(s) rep- resented in the shrine. The shrine is constructed with six re- cesses that can receive the head of a kneeling petitioner. In pre-Reformation times, prayers were spoken while petitioners knelt at the shrine with their heads in its recesses (Figure 2, right). What did a petitioner hear? Did the shrine’s acoustical architecture enhance the petitioner’s experience? My acousti- cal experiment at the shrine sought to find the difference in speech quality and spectrum levels heard with one’s head in the shrine versus one’s head outside the shrine. I used head- worn binaural microphones to create a high-quality digital recording made with the talker’s (my own) head first inside (see Multimedia File 1 at acousticstoday.org/lubman-multi- media) and then outside the shrine recess (see Multimedia File 2 at acousticstoday.org/lubman-multimedia), with the same vocal effort maintained in both recordings. I then pro- duced a graph of the apparent gain with the head inside the shrine (Figure 2, left), across third-octave bands in the hear- ing range, comparing the signal from both ears, that tracks how speech levels are greatly enhanced over the range of
Figure 2. David Lubman recorded binaural speech and calculated the appar- ent gain (left) produced by introducing one’s head (as if to recite prayers) into the recesses of the St. Werburgh Shrine (right) at Chester Cathedral in 2003. Figure courtesy of David Lubman.
human hearing when one’s head is located inside a shrine recess. From an interpretative perspective, recess acoustics elevate the petitioning event to “theater!” Within the shrine recesses, petitioners would hear their own voices reinforced, and they would thus be prompted to reduce voice level (in psychoacoustics, this is known as the Lombard effect). Inside the recesses, petitioners would be less aware of other sounds in the cathedral. The petitioners’ voices are reverberated, creating a mysterious-sounding “reverberant halo,” an effect that might seem like talking to another world. In this physi- cal and religious context, the auditory percept of proximity may be interpreted as spiritual intimacy. My reconstructive experiment in re-creating petitioners’ aural experience is a way of re-creating history, demonstrating how sensory ex- perience is another way of knowing.”
Lubman’s study of the Shrine of St. Werburgh provides an empirical complement to historical archaeology, which draws heavily on written texts for experiential accounts. Lubman’s experimental reconstruction produced a recorded demon- stration, backed by acoustical metrics, for the architectural transformation of speech within the shrine recesses. Via ar- chaeoacoustics, the effects that were once only possible to ex- perience in person, in situ, can be demonstrated off-site via Lubman’s audio recordings (see links above).The quantitative data from the archaeoacoustical experiment detail the amount of vocal enhancement specific to the experimenter, yet analy- sis of its frequency dependency enables the estimation of the shrine’s acoustical effects for other talkers, thus making the research extensible to archaeological estimations. Archaeo- acoustical scenarios that could be modeled using Lubman’s data include charting the difference in acoustical feedback for people with different vocal ranges and characterizing a range
30 | Acoustics Today | Winter 2018