In Situ Acoustic Analysis of Two Twentieth-Century Heritage Carillons
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Orr Herit Sci (2021) 9:16 https://doi.org/10.1186/s40494-021-00482-8 RESEARCH ARTICLE Open Access In situ acoustic analysis of two twentieth‑century heritage carillons Scott Allan Orr* Abstract Carillons are a diverse and global form of musical and civic heritage: musical instruments comprised of a series of 23 or more bells, typically hung in a tower-like structure, tuned chromatically and played from a touch-sensitive manual and pedal console using an elaborate mechanical action. Carillon bells have a distinct series of musical overtones which should be accurately tuned to one another and with other bells they sound alongside. Although these over- tones have been previously studied ex situ, this study assesses the acoustic characteristics of two early-twentieth century carillons in Toronto, Canada as a combination of structure, bells, and mechanical action. Thus, the instrument and its context are considered holistically, more accurately refecting the musical sensitivity of a carillonist. Spectral analysis of audio samples of each bell at diferent musical dynamic levels enabled the analysis of the acoustic qualities of the bells and the mechanical action of the instruments. The tuning of bells in the instruments varied; most impor- tantly, there was a signifcant diference between the audial intensity of the bell tones produced by the instruments, demonstrating the importance of the mechanical action as part of the ‘carillon system’. This was represented with a resistive power-law model, that represents the sensitivity of intensity to carillonist musical dynamic level. A discussion of the implications for artistic and heritage practice follows. Understanding the in situ physical acoustics of the carillon as a holistic instrument in its context informs performers, arrangers, and composers of how they can best embrace the instrument’s unique qualities to improve artistic pursuits and support the appreciation of carillons as heritage instruments and function as civic voices. Keywords: Musical heritage, Bells, Bell tuning, Historic instruments Introduction Many carillons are important heritage landmarks and A carillon (derived from the French; Dutch: beiaard; are an integral part of local community identity and German: glokenspiel) is “a series of at least 23 tuned culture. In the Low Countries where the instrument bells, played from a keyboard that allows expressiveness originated, 56 belfries of Belgium and France have been through variation in touch” [1] that may be transposed. collectively inscribed as a World Heritage Site since 1999 A standard carillon generally includes four chromatic (expanded in 2005) [2]. Teir outstanding universal value octaves (about 49 bells), which vary in weight from many is derived from their representation of the winning of tonnes to a few kilograms. Te bells are operated from a civic liberties and testimony to a range of architectural console comprised of a series of wooden keys (‘batons’), styles prevalent from the eleventh to seventeenth cen- arranged over two rows in a typical keyboard confgu- turies. Te instruments and their towers have become ration, and a pedalboard that doubles up the control of a strong component of regional cultural identity. More some of the largest bells (typically one and half to two recently, under the Convention for the Safeguarding octaves). of the Intangible Cultural Heritage [3] there has been a programme to safeguard the carillon culture that exists *Correspondence: [email protected] in seventy-six cities and villages of Belgium and in thirty Institute for Sustainable Heritage, University College London, 14 Upper countries worldwide [4]. In the twenty-frst century, Woburn Pl, London WC1H 0NN, UK © The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. 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Orr Herit Sci (2021) 9:16 Page 2 of 15 carillons have become strong voices for fostering equal- Gerken provides excellent examples of thinning out ity, diversity, and inclusion in communities [5]. texture while retaining harmonic structure [18] for While the structures in which the instruments are arrangement and transcription purposes. On the whole, housed present complex challenges to heritage manage- these guides are based on experiential practice of play- ment, additional challenges are posed by the nature of ing the carillon and composing and arranging music for carillons as mechanical instruments. Although no robust the instrument. study has been undertaken, formal and informal protec- Tis lack of literature is—in part—due to a lack of sci- tion is generally given to the bells within the instrument. entifc documentation on in situ acoustics of carillon Due to this, many carillons dating from the seventeenth bells. Te authoritative texts on carillon bell acoustics to twentieth centuries are still comprised of several of were undertaken in isolated conditions and utilise stand- the bells originally installed in the instruments. Over the ardised mechanical strikes to initiate sound [19–21]. Tis course of the twentieth century several technical inno- is strikingly diferent to the informed touch of the experi- vations improved the control a carillonist had over the enced carillonist, who adapts the input force depending musical capabilities of the instruments. Tese were pri- on the response from the weight of a clapper to produce marily improvements in the mechanical action and fab- a balanced sound landscape. Tus, the perceivable acous- rication techniques for bells that expanded the typical tic character of bells in the instrument is diferent in situ range of the instruments compared to their historical than in controlled experimental conditions. One excep- precedents during earlier centuries. Due to this, mechan- tion is [22], who characterise modal frequency, exponen- ical actions of carillon instruments have frequently been tial decay rate, and initial complex amplitude from audio upgraded and replaced with little care of their potential samples taken in situ; it is notable that the decay rates are heritage value. Research on preserving original integrity analysed in the context of the non-neglible ambient noise and material of carillons is typically limited to the bells of the campus environment. However, these samples do themselves [6]. Tus, material value is ascribed to only not represent the dynamic musical input of a carillonist. part of the instrument. Instead, emphasis is placed on Although bellfounding has incorporated technolo- the intangible heritage value and role of the carillon as gies as they have become available (such as 3D scan- an instrument with a civic voice, which necessitates the ning [23]), it still incorporates elements of a traditional technical improvements of the instrument to enable a craft. Each carillon bell cast—especially those fabricated modern standard of artistic performance. While the pres- prior to electronic frequency analysers—possesses a ervation of material authenticity has been discussed in unique sound colour based on the balance of the frequen- depth by restorers of other instruments (e.g. organs [7]), cies produced and their relative intensities. In contrast to and many challenges have been identifed for heritage the landmark work published by Lehr in 1951 [24] that instruments more broadly [8], discussion about the con- focuses on seventeenth-century instruments, this study servation and restoration of heritage carillons has been analyses twentieth-century instruments founded with very limited. modern techniques. Notably, these instruments were Composing and arranging musical compositions for tuned with a mechanical lathe but without electronic the carillon is complicated by: analysis. Tis study investigates the physical attributes of two • a lack of damping mechanisms, heritage carillons in Toronto, Canada, and subsequently • extended, but varied sound decay periods, applies spectral analysis to analyse the in situ frequency • the complex, prominent overtones associated with and sound intensity of the fve primary overtones at dif- each bell. ferent musical dynamic levels. Testing the acoustic char- acteristics of the bells in situ means that the transmission Many introductory guides have been published to system (the mechanical action) is considered as an inte- encourage and aid composers interested in the instru- gral component of the instrument, which can greatly ment [9–12] and more recently [13], although these impact its musical capabilities. Tis study identifes focus on the physical limitations of the player and the characteristics that