# Ambulance ambiences and siren harmonisations: Applied acoustics research and sound/music design in emergency ambulance vehicles

Robin Mcginley, Atienza Badel Ricardo

► To cite this version:

Robin Mcginley, Atienza Badel Ricardo. Ambulance ambiences and siren harmonisations: Applied acoustics research and sound/music design in emergency ambulance vehicles. 5th International Congress on Ambiances. Sensory Explorations, Ambiances in a Changing World, Mohammed Boubezari, Universidade Lusófona, Lisbon; Cristiane Rose Duarte, Universidade Federal do Rio de Janeiro; Ethel Pinheiro, Universidade Federal do Rio de Janeiro; International Ambiances Network, Oct 2024, Lisbonne, Portugal. *hal-05323489*

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L03

AMBULANCE AMBIENCES AND SIREN HARMONISATIONS: APPLIED ACOUSTICS RESEARCH AND SOUND/MUSIC DESIGN IN EMERGENCY AMBULANCE VEHICLES

AMBIENTES DE AMBULÂNCIA E HARMONIZAÇÕES DE SIRENES: PESQUISA DE ACÚSTICA APLICADA E PROJETO DE SOM/MÚSICA EM VEÍCULOS DE AMBULÂNCIA DE EMERGÊNCIA

Robin McGinley

Chair of Programme and Course Leader, International MA in Curating Art
Stockholm University, Sweden
robin.mcginley@arthistory.su.se

Ricardo Atienza

Associate Professor in Sound in Art and Media
Aalto University School of Arts, Design and Architecture. Helsinki, Finland
richardatienzab@gmail.com
## ABSTRACT

This paper offers an overview of the process and preliminary results of a collaborative research project, commissioned by Stockholm Regional Council Culture Department and AISAB, the largest provider of ambulance care services in Stockholm, Sweden. The project aimed to explore, in practical terms, how artistic and design methods could transform and improve the experience of ambulance interiors. To this aim, different artistic and design disciplines were convoked, notably sound art and symphonic orchestral music, material artistic practice and architectural lighting design. Focusing here on the music and sound design aspects, the resultant installation hardware and sound materials were subsequently deployed and tested within an operational ambulance space, with initial feedback from paramedics and patients utilised to begin to ascertain the effectiveness of the project's contribution to creating a more pleasant and engaging soundscape and acoustic experience within this singular, fast-paced and dynamic healthcare environment.

**KEYWORDS:** Sound art & design. Healthcare environments. Interior experience of ambulances. Sound attention masking. Co-design workshops.

## RESUMO

Este artigo oferece uma visão geral do processo e dos resultados preliminares de um projeto de pesquisa colaborativa, encomendado pelo Departamento de Cultura do Conselho Regional de Estocolmo e pela AISAB, o maior fornecedor de serviços de ambulância em Estocolmo, Suécia. O projeto teve como objetivo explorar, em termos práticos, como os métodos artísticos e de design poderiam transformar e melhorar a experiência dos interiores de ambulâncias. Para tal, foram convocadas diferentes disciplinas artísticas e de design, nomeadamente a arte sonora e a música orquestral sinfónica, a prática artística material e o desenho de iluminação arquitetónica. Focando aqui nos aspectos de música e design de som, o hardware de instalação e os materiais sonoros resultantes foram posteriormente implantados e testados dentro de um espaço operacional de ambulância, com feedback inicial de paramédicos e pacientes utilizados para começar a verificar a eficácia da contribuição do projeto para a criação de um ambiente mais uma paisagem sonora e uma experiência acústica agradáveis e envolventes neste ambiente de saúde singular, acelerado e dinâmico.

**PALAVRAS-CHAVE:** Arte sonora e design. Ambientes de saúde. Experiência interior de ambulâncias. Mascaramento de atenção sonora. Workshops de co-design.

# 1. INTRODUCTION AND OVERVIEW
OF THE RESEARCH FIELD

The pilot project 'Art in Ambulance Healthcare' (konst i ambulanssjukvården) was initiated in 2022, as a collaboration between the Cultural Department at Stockholm Regional Council (Region Stockholms kulturförvaltning) and AISAB
(Ambulanssjukvården i Storstockholm AB), a subsidiary company of the regional council, which provides ambulance care services throughout the Greater Stockholm area. Amongst its many remits and assignments, the council's cultural department, through its section for public art, and its affiliated competence development centre for art and health, is responsible for contemporary art within health care environments, including hospitals

and other health care locations throughout the region (which the council itself directly manages). This includes the administration and deployment of a large public art collection throughout its various healthcare facilities, together with the commissioning of new artworks and project initiatives designed to be presented and implemented across a range of healthcare contexts.

The current project developed within this institutional framework, and led to the commissioning of a process of experimentation, participatory workshops and activities to investigate the possibilities of installing applied ideas from sound design and music, as a means towards conceiving the ambulance interior as a space proper to the presentation of contemporary art, but also how such an initiative might contribute to the experiential improvement of these challenging environments for paramedic crews and patients. The wider project also included objects and visual elements created by artist Pia Sandström, together with a new and enhanced interior lighting design by Rodrigo Muro and Foteini Kyriakidou, from the Architectural Lighting Design Division of the School of Architecture and the Built Environment at The Royal Institute of Technology (Kungliga Tekniska Högskolan - KTH) (Pilotprojekt i ambulans, 2024). However, the current paper will focus exclusively on the process and preliminary outcomes of the sonic dimensions of the project.

## 1.1 Overview of the Research Field

The attendant research field relating to creative and artistic interventions within ambulance environments is sporadic and intermittent. Therefore, this paper will contextualise the current project by offering an outline highlighting interventionist strategies within ambulance environments and clinical practices, originating from a range of governmental, municipal and academic research contexts, as well as initiatives developed by ambulance crews themselves. One of the first examples that caught the attention of the project team early on, was a news item from India, which was syndicated internationally, and involved a suggestion from Nitin Gadkari, Minister of Transport and Roadways, that the customary sound of the ambulance siren should be replaced, throughout the country, by the more pleasant and amiable sounds of instruments from traditional Indian classical music, specifically playing a piece of music that is well-known to the general populace, and associated with the state public radio broadcaster All India Radio (AIR), also known as Akashwani (Pentreath, 2021; Pti, 2021). Despite extensive coverage, it is unclear whether the proposed change was ever implemented within live ambulances. Nonetheless, such a proposal underlines the potential for questioning the widespread public use of ambulance siren
sounds, and that such creative changes and interventions are at least conceivable, even at municipal and national levels. Innovation within ambulance vehicle interior design can also derive from academic research contexts, such as The Royal College of Art's collaborative project with the NHS and others from 2011, to improve the layout, ergonomics and clinical efficiency of the space in terms of the treatment area, crew working conditions and patient experience (Hamlyn et al., 2011). A further example, from the Swedish context, involved Jonas Ahnmé and students from the department of industrial design at Konstfack University of Arts, Crafts and Design in Stockholm who, in 2015, completed a project in collaboration with the National Association of Ambulance Personnel (Riksföreningen för Ambulansjuksöterskor) to develop alternative prototypes and design proposals for the functioning and work environment of future ambulances (Forslind, 2014). As we also found out from the current research process, through engagement with the Swedish company Eurolans, who are the main supplier of modification and emergency vehicles in the Nordic region, the design specifications for ambulances are generally developed in consultation with ambulance healthcare providers, with a high level of differentiation regionally, also according to prevailing statutory requirements and regulations. The above examples thus demonstrating the potential for creative and design-led engagement within such processes.

Regarding the deployment of visual arts within ambulances, such initiatives can also come from ambulance crews themselves, as evidenced by an example reported in mainstream media by the Canadian Broadcasting Corporation, of an ambulance crew in Quebec who piloted a project of installing reproduction artworks or photographs onto the ceilings of ambulance interiors, as a means towards stress relief and visual diversion for patients during transit ("Quebec Paramedics Want to Install Art to Ease Ambulance Stress," 2022). Although slightly ad-hoc in arrangement, and anecdotal as a news item, there is nonetheless a useful suggestion here, as well as a highlighting of the need for enhancement of the visual sphere for patients and crews alike. Similarly, in terms of the auditory dimension, Jānis Indulis Dundurs and Inka Janna Janssen (2020) have investigated the potential adverse health effects for paramedics of constant exposure to high sound pressure levels throughout their shifts, due to siren usage and differing vehicle speeds, whereas Katie L. Myers (2013) demonstrates that one approach, deriving from applied music therapy, for improvement of the ambulance interior soundscape, especially from the patient perspective, is through the application of patient-selected genres and pieces of music, thereby enhancing patient well-being and overall experience of ambulance transport.

## 2. PRELIMINARY WORKSHOPS

The project's first workshop took place in September 2022, with the participation of representatives of paramedics and ambulance crews from AISAB. The aim of the workshop was essentially twofold, and entailed not only introducing the idea and potentials of artistic intervention into the interior ambulance environment, but also
opening up an initial space for discussion, encouraging participants to speculate
on where within the ambulance interior it might be possible to intervene creatively
and artistically, whilst also taking into consideration how such interventions might
function as improvements, regarding environmental and experiential conditions, for
patients, as well as for ambulance crews themselves.

This was achieved by initially sharing with workshop participants a number of
examples of creative/artistic and design projects and initiatives, together with recent
examples drawn from the attendant research literature (some of which are outlined
in section 1.1). These discussion examples assisted with situating the possibility of
artistic/creative intervention, whilst also emphasising that such ideas and initiatives
have already been subjected to quite a high level of discussion, critique and activity
internationally. The fact that the examples were all derived from the immediate
ambulance context provided a 'something to hold on to' factor, also grounding the
discussion in concrete cases, and encouraging further elaboration and consultation,
geared towards and assimilated to the local context in Stockholm.

Following this segment, the workshop continued with a discursive presentation slide, which brought together a number of factors and parameters for consideration in terms of interventional possibility:

<figure><img src="image_2.png" /><figcaption>Figure 1a. Excerpt from the workshop presentation, detailing the discursive slide on environmental and sensorial factors and parameters.</figcaption></figure>

<figure><img src="image_3.png" /><figcaption>Figure 1b. External view of the ambulance in which the prototypes were installed and tested.</figcaption></figure>

This was followed up with a workshop component involving visiting a couple of
ambulance vehicles in the garage with participants and, in an informal and freeform
way, transferring and rapidly applying discursive ideas to the ambulance interior
itself, in situ. This was followed by a summative plenary discussion.
# 3. DESIGN AND DEVELOPMENT OF THE ADDED SOUND ENVIRONMENT

## 3.1 Recordings and analysis

In order to experience first-hand the ambiences surrounding paramedic staff and transferred patients, we were invited to join the team for a full shift. During this journey we made a number of ambisonic (3-dimensional) recordings of the ambulance sonic environments in motion, at different speeds, corresponding to different types of roads and levels of urgency involved.

<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /><figcaption>Figure 2a. Average frequency distribution of the sonic environment inside the ambulance for four different speeds. In horizontal frequency range in Hertz (logarithmic scale), in vertical relative decibels.</figcaption></figure>

<caption>Figure 2b. Interior view of the ambulance cabin.</caption>

This was followed by an acoustic analysis of the resulting sequences focused on spectral distribution, rhythmical patterns, etc. The results show a heavy saturation of the low frequency spectrum, in agreement with the noticeable vibration experienced inside the cabin, and a pronounced progressive decay as we ascend in the frequency domain to finally reach a rather silent medium-high and high frequency band (see figure 2). We can see in this analysis the result of the acoustic treatment applied around the cabin of the ambulance, an unbalanced insulation highly efficient in the upper frequency range while mostly unable to absorb the vibration of the vehicle in motion, potentially even amplifying it. As a result of irregularities of the road surfaces, vibration emerges discontinuously along the timeline of a journey, and constitutes a distinct and characteristic layer of the ambulance sonic environment that we will treat specifically.

## 3.2 First Prototype

Based on the previous acoustic results and workshops, we designed a first prototype of an added sonic environment to be experienced, altered and evaluated by crew members in situ. In material terms, it consisted of a basic setup easy to install and remove from the ambulance afterwards: a tablet with a graphical user interface, connected via Bluetooth to two portable speakers attached to the ceiling of the cabin. This first version of the GUI allowed testers to mix three different sounds including independent gain controls for each, and to modify through a bidimensional pad two parameters in the resulting mix: the dominant frequency range (through a bandpass filter, X-axis of the pad) and the level of grain of the resulting texture (through a reverberation effect, Y-axis).
Crew members were invited to test this sonic environment and graphical user interface during a trip in the ambulance, and to provide feedback on it. Six people took part in this first evaluation and their comments and suggestions were integrated into the second prototype. We will not focus in this paper on the specific results and sound materials of this first phase but, as a summary, we could observe a positive reception of the general concept and environment, including a number of suggestions for improvement of the GUI (added functions and flexibility) and of sound control (advocating for a more flexible sound design of each independent sound material in the mix, for example).

## 3.3 Second Prototype. Physical Setup and GUI

Based on the feedback and observations collected with the first prototype, a number of significant modifications were brought into prototype 2.

First, concerning the physical setup, a specific line-array speaker was designed and built that could be integrated seamlessly in the limited volume of the cabin, while responding efficiently to the sonic spatial requirements of the added soundscape (figure 3).

<figure><img src="image_6.png" /><figcaption>Figure 4. Graphical User Interface.</figcaption></figure>

Regarding the graphical user interface (GUI, figure 4), it incorporated a number of new features and further flexibility in terms of sound design control. Users are invited to create a background added sonic environment (Layer A) by choosing among four different sonic textures, mixing them freely (independent gain control) and fine-tuning each one of them independently in terms of frequency range and grain (as described for prototype 1). Once the mix is ready, a button (in red "My mix") allows them to store their preferred sound blend, data that is collected and will be later analysed. The system can be operated manually or in automatic mode, to free ambulance crew when needed.

This GUI also offered a gain control on two extra sound layers that will be described below, Layer B, ("Bump"), a reactive layer to the vibration impacts caused by road irregularities, and Layer C, orchestral textures responding to the different siren modes of the ambulance (see section 4).
This interface was created with the graphic programming environment *PureData* (Pd) and the native Pd GUI rendering *MobMuPlat*.

## 3.4 Second Prototype. Description of the added sound environment.

The added sonic environment is composed of three distinct sound layers, responding to three different sonic issues and materials:

**Layer A:** a discontinuous layer automatically reacting to vibration, to the low frequency transients due to bumps and discontinuities in road surfaces. A motion detection sensor (embedded in the tablet) randomly triggers over a certain threshold one of the recorded bells of a wind chime displaying a modal scale. The attacks of the bells have been removed in order to blend perceptually the low frequency transient with the bell sound, operating here as a lasting resonance of the main impacts, colouring and rebalancing it in spectral terms. This added resonance intends to produce an occasional and low-density layer, and its gain can be controlled by the ambulance staff or even totally silenced.

**Layer B:** Based on information or attention masking theories (Nilsson et al., 2010; Atienza & Billström, 2012; Eriksson, 2017), its aim is to divert the attention from the background noise and general acoustic environment of the ambulance dominated by motor sounds, vibration, sound signals from medical equipment and characterised by a dry and inert acoustic response (plastic interior surfaces for hygienic reasons). *Attention masking*, as opposed to traditional *energy masking*, intends not to hide but to divert the attention from a disturbing sound source through minimal added sound interventions at low gain.

Four sonic textures are proposed for the users to choose among, blend and transform. They are each of a different sonic nature and present as well different textural characteristics. This broad selection of materials aims at providing a wide palette of possibilities for the users to explore, and for the design process itself to understand which textures might be most appreciated and operational in collaboration with users:

* **A:** *Material* sound produced by sleigh bells in a continuous gentle movement, plus an electroacoustic treatment for obtaining a dense texture formed by parallel ascending and descending *slow glissandi* (see figure 5a).

* **B:** *Natural* soundscapes from water (river, sea), wind, fire, etc., blend together to create a complex and unstable texture which, in perceptual terms, continuously shifts and changes *identity*.

* **C:** *Instrumental* texture (cello) composed of several waves of a similar continuous bow action, playing a single -different- tone each, and at slightly different tempi. It results in a continuous texture, whose properties display a constant but very gradual mutation, almost imperceptible when not paying attention to it.
* D, Synthetic sound based on a Karplus-Strong algorithm providing a point-based, transient texture that follows a harmonic series scale and a variable rhythmical pattern (see figure 5b).

As mentioned previously, these textures described here are the raw materials that will be later moulded by ambulance crew members through the provided GUI (Sound tuning pad, see figure 4, GUI). Consequently, their frequency ranges will be limited through a band-pass filter, and an impulse-response reverberation effect will allow the manipulation of their grain depth and resulting spatial experience.

**Layer C:** Orchestral layer reacting to the three different siren modes (see section 4).

<figure><img src="image_7.png" /><figcaption>Figure 5. Spectrogram of sonic textures A (material sound, left image) & D (synthetic sounds, right image). 30 seconds sequences. Note the dominant high frequency range in both cases, benefiting from almost no competition from the background sound of the ambulance in motion, as shown in figure 2.</figcaption></figure>

## 4. SIREN HARMONISATIONS: COMPOSITIONAL APPROACHES AND RECORDING THE ORCHESTRA

As indicated above in section 1.1, the abrasive sound of the ambulance siren is apt to generate debate and consternation within urban experience. Therefore, in developing a project generating auditory experiences within ambulance interiors it was felt, by extension, to also address the interior experience of the ambulance siren, when sounding. To this end, a series of orchestral harmonisations of the siren were created, based around the pitched and harmonic relationships inherent to the siren sound, with the aim to place this within a musical context and foundation - softening and smoothing out its impact, when heard within the vehicle. Similar to the other sonic and acoustic environmental elements described above, these harmonisations form a selectable mode within the interactive sound installation system.

Three distinct sounding modes are currently utilised by the sirens mounted on AISAB's ambulance vehicles. Driver activated and controlled, a main siren sound which alternates between a fairly familiar two-tone electronic oscillation, which is intercut at intervals with a contrasting signal involving a frequency sweep in upward motion. To attract further attention in specific instances and situations, the driver can also choose to trigger discreet klaxon blasts, which interpose and override the other sounding modalities.
Four different harmonisations were composed and orchestrated for full symphony
orchestra, each one manifesting as a short orchestral fragment, deriving from the
sounding states outlined. As the commissioner for the project, Stockholm Regional
Council, is also the principal funding partner of The Royal Stockholm Philharmonic
Orchestra, it was arranged for the orchestra to record this material at Stockholm
Concert Hall (Konserthuset) in October 2023. The symbolic value of having one of
the most prominent orchestras in the country record these vignettes, which were then
installed into a working ambulance, certainly adding a further dimension to the process.

The four orchestral harmonisations included 17 *Klaxon Harmonies*, a series of
harmonic combinations, which correspond to the sound of the driver-operated
klaxon sound. Performed and recorded successively, as a series of orchestral hits,
when inside the ambulance, these chords mask the blast of the sounding klaxon,
with each chord triggered, in a non-linear fashion, by the manual use of the horn.
Another harmonisation, entitled *Polyrhythmia* is a piece based on a natural harmonic
series, embedding the two tones of the main siren sound. A series of rhythmical cells
have also been derived from the 120 BPM of the siren pulse. Each instrument plays a
number of passages, composed of a repeated cell and a different rhythmical pattern,
which both emerge and fade out smoothly, in an undulating motion.

<figure><img src="image_8.png" /><figcaption>Figure 5: The Royal Stockholm Philharmonic Orchestra, recording the Ambulance Siren Orchestral Harmonisations, Stockholm Concert Hall (Konserthuset), October 2023.</figcaption></figure>

A further treatment of the main siren sound was **Main Siren - Slow (4x5)**, a series of diatonic chords suggested by the harmonic orientation of the signal. These chord sequences are deployed through a series of intersecting loops, of uneven lengths, and scored for five semi-independent instrumental groups, intersecting instrumental families. The piece is characterised by long, held notes and foregrounds a kind of harmonic stasis throughout. This obscures the incessant oscillation of the siren sound, whilst offering it a slow-moving harmonic grounding. A final example, **Infinite Canon**,
is based upon, and utilises, the eight-bar fragment which comprises J.S. Bach's **Canon 5 a 2 per Tonos** from *Das Musikalische Opfer, BWV 1079 (1747)*. Bach inscribes this fragment, "Ascendenteque Modulatione ascendat Gloria Regis". Thus accordingly, the piece embodies a musical process whereby the canonic material is successively heard throughout the full range of the orchestra, from lowest to highest instruments, with each successive repetition modulating upwards. Bach's instruction gives rise to a psychoacoustic sensation of the canon infinitely rising in pitch, akin to such contemporary electroacoustic phenomena as Shepherd tones, or the infinite loops of M.C. Escher lithographs. Synchronised with the frequency sweep siren sound, and thereby providing a spectral accompaniment in perpetual motion.

## 5. CONCLUSION

The setup described above (prototype 2) has been permanently installed in one of AISAB's vehicles since December 2023 and is being tested in real situations. Information on preferences and usage is being collected and will be the object of future analysis and further improvements. However, the feedback collected during this prototyping process already provides us with a number of relevant elements in terms of design of the GUI and sound preferences.

As a general reflection, we commenced this collaboration with relatively sceptical expectations from crew members regarding a potential positive impact of added sound within their daily working environment. Being confronted by a saturated and stressful environment, the perspective of new added elements was a reasonable cause for concern. This perspective evolved throughout the co design process in which they could provide feedback on sound materials, and gained control of sound parameters, and the use of the entire added sound system: paramedics are free to decide if and how to use these added sound layers, which is an essential component within such environments, for their potential acceptance.

Regarding the GUI, crew requests point in two apparently contradictory directions: on one hand an intuitive and simple interface in terms of use, not requiring any specific knowledge or focus as they are already confronted by a highly technical and complex environment, whilst on the other a flexibility and a high level of control of sound parameters to accurately adjust sound components to their taste. As a result, in addition to the improvements introduced in prototype 2, a discussion has also been engaged on automatic modes, for quick and simple use, as well as co-designed presets prepared in advance for a number of specific situations and to be later triggered when required.

Useful feedback has also been collected during the process regarding the characteristics of the sound materials themselves: a preference for continuous sound textures that could more easily blend within the background environment of the ambulance, with limited transients or marked rhythmical patterns (pulse), operating at low gain and avoiding extreme frequency ranges that could be excessively present in perceptual
terms. Gain has proved to be a relevant parameter on which almost all users agree, placing it within a narrow range, just above perceptual presence, but not any further.

These observations and the feedback collected from prototype 2 will be evaluated and implemented in a final permanent installation to be implemented during 2024-2025.

## 7. BIBLIOGRAPHY

Atienza, R., & Billström, N. (2012). Fighting “noise”= adding “noise”? Active improvement of high-speed train sonic ambiances. Ambiances in action. International Congress on Ambiances, Montreal 2012

Quebec paramedics want to install art to ease ambulance stress. (2022, January 16). CBC News. https://www.cbc.ca/news/canada/montreal/artbulance-pilot-project-1.6315254

Dundurs, Janis Indulis and Janssen, Inka Janna. (2020). Influence of Noise in Ambulance Vehicles on Emergency Personnel. Noise and Environment, IntechOpen. https://doi.org/10.5772/intechopen.87872

Eriksson, M., Atienza, R., & Pareto, L. (2017). The Sound Bubble: A context-sensitive space in the space. Organised Sound, 22 (1), 130-139. https://doi.org/10.1017/S1355771816000418

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Myers, Katie L. (2018). The Use of Patient-Preferred Music to Improve Patient Experience during Interfacility Ambulance Transport (MMus dissertation) Florida State University

Nilsson, M. E. et al. (2010). Auditory masking of wanted and unwanted sounds in a city park. Noise Control Engineering Journal, 58(5), 524-531.

Pentreath, R. (2021, September 20). India to replace ambulance sirens with traditional flute and tabla music. Classic FM. https://www.classicfm.com/music-news/india-ambulance-sirens-replaced-flute-tabla-instruments/

Pti. (2021, October 5). Indian musical instrument sounds for vehicle horns soon: Nitin Gadkari. The Times of India. https://timesofindia.indiatimes.com/auto/news/indian-musical-instrument-sounds-for-vehicle-horns-soon-nitin-gadkari/articleshow/86773005.cms

Pilotprojekt i ambulans. (2024). Region Stockholm. https://www.regionstockholm.se/halsa_sjukvard/halsa/kulturochhalsa/kompetenscentrum-for-kultur-och-halsa/innovation-och-forskningsprojekt/pilotprojekt-i-ambulans/