Carillon Bells Research Articles

Carillons in the Soundscape of Gdańsk1

From 1561, the chiming of the Main Town Hall automatic carillon bells became a permanent component of the City of Gdańsk soundscape, to which, from 1575, were added the chimes of the St Catherine’s Church tower ‘striking device’ in the Old Town. The first automatic carillon comprised fourteen bells, whereas the other ‘device’ probably had several. It was not until 1738 that St Catherine’s Church acquired a large carillon with a keyboard as well as a mechanism for automatic playing. This article investigates the possible reasons why carillons were built for the Main Town Hall and St Catherine’s Church in Gdańsk, describes the bells and the mechanisms for automatic playing of both instruments and considers the repertoire by which their chiming filled the City of Gdańsk soundscape over the centuries.

In situ acoustic analysis of two twentieth-century heritage carillons

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 overtones 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 reflecting the musical sensitivity of a carillonist. Spectral analysis of audio samples of each bell at different 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 importantly, there was a significant difference 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.

Objective estimation of the tuning features of historical carillons

The carillons of the Mafra National Palace are undergoing a restoration project. Together, the pair of carillons represent the largest surviving 18th century carillons in Europe. To guarantee the historical significance of these outstanding musical instruments, a detailed diagnosis of their current physical tuning state was achieved and results were analyzed with respect to historical, acoustical and musical concerns. In a first stage, we developed a suitable polyreference modal identification technique to infer the tuning status of bells from their modal parameters and we then systematically performed in-field modal testing experiments on a selection of historical bells of the Mafra carillons. For each carillon bell, tuning charts displaying the internal frequency relationships between its most important partials were obtained, as well as the mode shapes, decay times and beating frequencies between modal-doublets for every single musical partial of the bell. In a second part, since carillon bells also must be tuned very accurately one relative to the others in order to play in tune, the important topic of estimating the reference pitch and musical temperament of carillons was addressed by devising optimization techniques, here tentatively based on the actual modal frequencies of the bells. After presenting the modal identification procedure and optimal strategies developed for this work, the feasibility and interests of this instrumental approach are finally illustrated for the two carillons of Mafra.

Acoustics of Western and Eastern bells, old and new

The modes of vibration and sound radiation from tuned church bells, carillon bells, handbells, ancient Chinese two-tone bells, and temple bells will be compared. Most bells have a circular cross section, but many ancient Chinese bells do not, and thus they have two different strike notes, depending upon where they are struck. The musical interval between these two strike notes is often near a minor third or a major third.

A carillon bell laboratory in an introductory physics of music class

The Physics of Music is a lecture and laboratory class which satisfies a quantitative physical science requirement. It is open to students of all majors. Students taking the class may or may not have musical backgrounds, and generally are not majors in the physical sciences. In this laboratory exercise, students record sounds of the bells of the Harris Carillon in the tower of WFU’s Wait Chapel. Using Audacity and other software, students generate frequency spectra of different bells. The prominent presence of minor thirds in the spectrum makes for a useful comparison between spectra of bells and typical concert instruments. In this lab, students identify spectral features of individual bells, find similarities and differences between different bell spectra, and observe the decay of spectral features over time. In this talk, I will describe some of the activities performed by the students in the lab and comment on some of the challenges of performing this laboratory exercise with students of varied musical and scientific backgrounds.

Traditional and operational modal testing of masonry vaults

This paper discusses the practical and technical differences between the usual form of experimental modal analysis (EMA) and operational modal analysis (OMA), as applied to Gothic-style masonry vaulted structures. In situ vibration measurements were collected from the masonry fan vaults of the National Cathedral in Washington, DC, USA. Instrumented impact hammer excitation was used during the experimental traditional modal analysis (TMA) tests, while excitation by peal bells, carillon bells, organ, an orchestra and chorus, and ambient noise were exploited for OMA. The acoustic inputs of the first four excitation types were measured using a microphone and were found to approximate a uniform acoustic excitation across the frequency bandwidth of interest during the carillon and the orchestra and chorus excitations. For both TMA and OMA, system identification was completed by the least-squares complex exponential method. The natural frequencies were found to be consistent for all excitation sources and modal test techniques. Certain natural frequencies found by TMA, however, were omitted from the sequence of frequencies as determined in the OMA. This paper illustrates that OMA is a suitable alternative to global vibration analysis of a masonry building, especially when there are concerns about the use of a hammer or shaker for this purpose.

The design of bells with harmonic overtones.

Musical bells have had limited application due to the presence of inharmonic partials in the lower part of their acoustic spectra. A series of bells has been designed that contains up to seven partial frequencies in the harmonic series beginning at the fundamental frequency. This was achieved by choosing geometries for finite-element analysis models in which as many purely circumferential bending modes as possible occurred at frequencies below any mode with an axial ring node. The bell models were then fine tuned using gradient projection method shape optimization and the resulting profiles were cast in silicon bronze. A range of bell geometries and timbres is analyzed using psycho-acoustic models and is discussed in relation to European carillon bells.

Assessing tuning and damping of historical carillon bells and their changes through restoration

The 46 bells of the historical carillon in Perpignan have been restored: taking them down, sanding their oxide layer, and resuspending them. Sound and vibration recordings were made at each stage of the restoration process. The modal frequencies and decay rates have been estimated by means of the matrix pencil algorithm, a parametric signal processing method, with a variance of ≈ 0.1% for the frequencies and a few percents for the damping rates. Tuning is accurate in general, except for the highest notes. The quality factors of the vibration go through a broad minimum in the 2 kHz region. Measurements reveal minute but consistent frequency changes of the order of a few cents. On average, the bells ring 15% longer since the restoration. The measurements also show that the damping rates were more consistent along the range of the instrument after restoration.

ON THE DEBOSSING, ANNEALING AND MOUNTING OF BELLS

Changes in the frequencies of the musical partials of various types of bells following debossing dismounting/mounting and annealing/quench annealing are reported. Debossing, dismounting and quench annealing lead to frequency drops, while mounting gives rises. Annealing can lead to frequency increases or decreases depending upon the maximum temperature employed and the initial residual stress. Qualitative explanations of these phenomena are given in terms of changes in crown stiffness, internal stress and alloy phase structure. These are supported by the results of X-ray diffraction measurements. Although the effects are all small they can be large enough to be detected by a reasonably musical car. This, together with the fact that the effects cannot be controlled, gives a plausible explanation of why modern bellfounders use vertical lathes for tuning, even with small carillon bells, and do not anneal bells when trying to control warble.

Acoustics of Eastern and Western bells, old and new

Bells have been a part of nearly every culture in history. The acoustical properties of many different types of bells are compared, including church bells, carillon bells, handbells, ancient Chinese two-tone bells, and temple bells from several countries. Special attention is paid to modes of vibration and sound radiation.

On the tuning of church and carillon bells

The whole area of the tuning of church and carillon bells is reviewed in an historical context. Experimental results on the tuning of a small carillon bell are reported and compared with the results of van Heuven for the ‘average Hemony bell’. Surprisingly, in view of the very different geometries of the bells, there is excellent agreement. This fact, coupled with unexpected nodal patterns for some of the carillon bell's modes, seems to shed some light on the classification of church bell modes.

Scaling of bells

The fundamental frequency of a bell has roughly the same dependence on thickness and diameter as flexural vibrations in a circular plate, and thus in designing a bell chime or ensemble of bells, it would be possible, in principle, to scale all dimensions proportional to 1/f. Tonal considerations often dictate otherwise, however, and in practice different scaling laws are found in ensembles of large and small carillon bells, church bells, handbells, and ancient Chinese bells that have been studied.

Modal analysis of a Korean bell.

Large temple bells have been cast in Korea for more than 1200 yr. Most Korean bells have a circular area, called a dangjwa, which provides a convenient striking point, and a sound pipe, called a eumtong, at the top. The asymmetry due to the dangjwa and the ornamentation gives rise to mode doublets and results in a slow beating, which is carefully controlled and considered to be an important characteristic of Korean bell sound. The vibrational modes of a small Korean bell have been studied, using holographic interferometry and modal analysis with impact excitation. The vibrational modes are somewhat different from those of carillon bells, tuned church bells, and handbells previously studied [see N. H. Fletcher and T. D. Rossing, ThePhysicsofMusicalInstruments (Springer-Verlag, New York, 1991), Chap. 21]. No (m,l*) modes are observed. Mode doublet splittings range from 1% to 9%. The fundamental (2,0) mode decays much more slowly than the higher modes of vibration, and thus determines the pitch of the bell. [A.P.’s visit was supported by a grant from Ecole Nationale Superieure des Telecommunications.] a)Student intern from Ecole Nationale Superieure des Telecommunications, Paris.

Warble in carillon bells: An investigation using neutron diffraction

It is speculated that warble in carillon bells can be caused by mode splitting as a result of internal strains produced by non-uniform cooling during casting. The neutron diffraction technique makes possible the measurement of internal strain and is here applied to a 6 1 2 in (166 mm) carillon bell with a pronounced 3 Hz warble. Internal strain variations with a 180° periodicity about the bell circumference were detected. From symmetry considerations this periodicity requires that all partials (other than m = 0) should have their doublets split. Measurements of the bell partials confirmed this splitting. The metallographic phases present in the bell metal were also determined and found to agree with expectations.

Tuning of bells by a linear programming method

A carillon bell is tuned by the removal of metal from the inner surface of the bell. Van Heuven [Acoustical Measurements on Church‐Bells and Carillons (De Gebroeders van Cleef, ’s‐Gravenhage, The Netherlands, 1949), Chap. IV] determined a set of tuning curves and derived a set of equations that relate the amount of metal removed to the relative alterations in the partial frequencies. This paper uses these equations as constraints in the formulation of the tuning problem as a linear program. An example illustrates the procedure.

Acoustics of Eastern and Western bells, old and new.

Bells have many modes of vibration whose modal shapes are characterized by the numbers of nodal meridians and nodal circles. In Western church bells and carillon bells, the bell is shaped so that the lowest mode frequencies are harmonically related. The subjective strike note is determined by three strong partial tones with frequencies nearly in the ratios 2: 3: 4. The pitch of a handbell, on the other hand, is determined by the frequency of the fundamental tone. In ancient Chinese bells, the vibrational modes occur in pairs, and two different tones result from striking at the sui and gu strike points. A new type of carillon bell has been developed in which the traditional minor third partial is replaced by a major third partial, thus changing the timbre of the bell.

Acoustics of Eastern and Western bells, old and new

Bells have belonged to nearly every culture in history. The oldest surviving bells from the Near East and China are thought to be over 3000 years old. Many ancient Chinese bells, by virtue of their oval shape, have two distinctly different strike notes, separated in pitch by about a major or minor third. Bells developed as Western musical instruments in the 15th and 16th centuries when bell founders learned how to tune their partials harmonically. The acoustical behavior of Western church bells, carillon bells, and handbells are compared to those of ancient Oriental bells. Recently carillon bells with a major third replacing the traditional minor third partial have been developed [A. Lehr, Music Percept. 4, 267 (1987)].

Vibrational modes of Chinese two-tone bells

The vibrational modes of a modern copy of an ancient Chou dynasty bell have been studied by means of holographic interferometry and by scanning the sound field near the bell. The modes are compared to those observed in church bells, carillon bells, and handbells, as well as other ancient Chinese bells. Modes tend to occur in pairs, one with a node at the xian or spine, and one with an antinode there; the frequencies of the two doublet members differ by about 3% to 10%. Bells of this type emit two distinctly different notes, depending upon where they are struck.

A comparative study of the normal modes of various modern bells

Finite element calculations of the normal modes of church, carillon, hand and fire-alarm bells have been made. Some of the results are presented and comparisons made which shed new light on mode classification.

III. From Theory to Practice

Modern digital computation techniques have made it possible to compute a base profile for a bell so that it will have some particular, predetermined eigenfrequencies. Practice has shown that with a combination of these modern techniques and the traditional skills of an experienced bell founder, a carillon bell can be made that contains an unconventional "major-third" partial and is in other respects at least as well-tuned as traditional carillon bells of high quality. An experimental movable carillon with 47 major-third bells was built and was found to be aurally quite distinguishable from a conventional carillon of comparable size. Criticizm on this new instrument comes mostly from professional carillonneurs, whereas other musicians or nonmusicians react generally in a positive way.