I would like to begin by inviting you to listen to the composition Border Amplitudes to engage with the crossings of four different (internationally recognized) borders. I recommend listening with your eyes closed, using high-fidelity speakers or headphones (this is a stereo mix). Additionally, please write down any sound you associate with (the crossing of) an international border.

 

 

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I often make this invitation in the form of an assignment in the seminars I teach on research methods and borders. I ask students to identify five to seven potentially indexical sounds of borders and the crossings thereof and elaborate on them. Borderlands are idiosyncratic spaces with ‘sensorial organizations’ of their own (see Ong 1991) and sound offers varied sensory and cognitive pathways to exploring them. The goal of this listening session is to spark a collective reflection upon certain features of borders, how people sound and are sounded by borders, how borders sound and what that reveals about them, about sound, as well as about who is listening. Borders are fields of sonic relations.

From a collection of loose clips resembling border vignettes, the piece has evolved into the current multilayered continuous composition through several exchanges with students and colleagues who engaged with previous edits.¹ As I played Border Amplitudes (or one of its diverse versions), I encountered startling descriptions of its content. This has significantly pushed me to continue experimenting with the composition. There is a transcendent quality of sound, Jonathan Sterne (2005) suggests, that challenges and produces individuals’ perceptions of the world. And as sound ‘settles on precise meanings or impressions, it metamorphoses into [other] sounds, images, odors, textures, colors’ (see Le Breton 2006:2).

A student from Pakistan viscerally described the sound of heavy guns being loaded as if in preparation to fire. A Portuguese student insisted the whole track had been recorded in airports, providing a vivid description of people boarding, identifying loud aircraft engines and in-flight white noise. A student from Brazil was certain she felt someone being body-searched. Another student from Colombia mentioned that at least one of the crossings was done on foot, something common in the context of South America. These and other accounts do not echo what was de facto recorded — at least, as far as I could tell from traversing, recording, and later listening over and over again to those borders.² Instead, such descriptions reveal the broad range of sensory perceptions and how we assign and derive meaning from sounds based on our unique experiences and diverse sociocultural backgrounds, how we recognize sounds as emanating from potential sources, or how they evoke an affective response even when the exact source of the sounds remains unidentified.³ As Helmreich suggests, often ’what people hear [and listen to]⁴ is related to how they think’ (2015:xx), in this case, about borders.

Through the conceptualization of amplitude(s), which I will sketch below, I aim to encompass these varied perceptions and experiences of borders—how they reach, touch, and affect us in different ways.  The sonic experience of borders defines these spaces, influencing how we engage with their physical and symbolic dimensions. I then provide the context and inspiration behind Border Amplitudes and conclude by exploring some of its audio and visual dimensions.

 

Amplitudes

Border Amplitudes engages with the ‘sonic bodies’ (cf. Min 2020) of the borders between Portugal and Spain; Spain and Morocco across the Strait of Gibraltar; Morocco and Mauritania with the Guerguerat Strip in between, which is partly controlled by the Front Polisario, in the occupied Western Sahara; and finally, Mauritania and Senegal across the river Senegal. Conceiving the border as a ‘sonic body’ implies thinking the (crossing) of a border not necessarily as (crossing) a mere demarcation, but as (traversing) a field of sonic relations. The crossings of these borders were experienced and listened to ‘nearby’⁵ Mbaye Sow, a Senegalese-Portuguese routier. Routier is the term used by African migrant men who regularly drive vehicles from Europe to West Africa to describe themselves (see next section). Despite being at the core of the piece, the conceptualisation of amplitude, as well as the audio and visual components of the piece, are sometimes tangential to routiers’ worlds. As the title implies, Border Amplitudes explores and experiments with the conceptual potential of amplitude not only to reflect upon and have a grasp of this specific set of borders but also to come closer to the wider empirical perception and knowing of borders more broadly.

In acoustics, sound is defined as transmitted back-and-forth mechanical vibrations that propagate through mediums such as water or air (see Berg 2024). The number of vibrations or cycles per second of a sound wave is defined as frequency (Hz), which determines (the perception) of pitch. Higher frequencies correspond to higher-pitched sounds, while lower frequencies correspond to lower-pitched sounds. Human hearing ranges between 20 Hz and 20 kHz but within this range all these frequencies are not perceived as being equally loud. To a great extent, the frequency response of our auditory system depends on amplitude. Amplitude stands for the pressure of sound waves, and plays the key role in loudness perception. The greater the pressure, the louder the volume, and the higher the decibels (dB). Dynamic range stands for the ratio between the lowest and highest recorded amplitudes.⁶ The diagrammatic representation of the sound wave (fig.1) helps illustrate and grasp some of these terms.

 

 

Increasing a wave’s amplitude will make it seem louder to the human ear. However, doubling the amplitude will not double the volume. Although amplitude and loudness are correlated, they are not the same. Amplitude cannot be accurately grasped without the aid of appropriate devices; thus, its perception, in the form of loudness, remains subjective and unique to each listener.

I must acknowledge that the thinking about borders in terms of amplitude(s) was significantly influenced by the visual representations displayed by recording devices and audio editing tools. Instruments as such configure what Helmreich calls ‘theory-laden’ devices, in that they play a central role in conceptualising what they make possible to capture (Helmreich 2016: 477). Indeed, the visual representation of a sound wave appears as a border template (see Fig.1): a more or less abstract and fixed demarcation (axis of time), that is, a borderline, which is criss-crossed by oscillating relations and exchanges that are perceived and experienced differently. Waveforms capture the ‘moving body of the border’ (cf. Min 2020: 232). Thinking in terms of amplitude helps capturing the ‘volumetry’ of borders (cf. Billé 2020), with the representation of amplitude visually evoking the (sonic) reach of borders. Amplitude recalls how borders touch us, involve us, sometimes from afar, hinting at the thickness or thinness of the crossing experience. Thinking about borders through amplitude blurs the (sometimes) hardline demarcation between both sides, revealing how they are entangled and in dialogue with each other.

The density and temperature of the medium through which sound is propagated, as well as the material properties of objects and surfaces encountered by sound waves are among the several factors that influence how sound travels, is received, perceived, and therefore also graphically represented. Additionally, ‘waveform audio’ is frequently used to refer to the actual recorded sound, rather than its graphical depiction.⁷ When Tara Rodgers (2011) posits that (the representation of) sound waves are sounds’ ‘biographical tracing’, it is not a mere metaphor. Waveforms do reflect the collective relationships and the social and material structures that underpin them.

With Border Amplitudes, I conceptually stretch the idea of sonic amplitude to emphasise the phenomenological dimension of borders, their heterogeneity and varied intensity, how borders are enacted, perceived and experienced through sounding and listening. With amplitudes, I recognise the importance of (the perception of) loudness and quietness, as well as what is within and beyond human hearing range (20 Hz to 20 kHz), and therefore also what can be inferred and reimagined through ‘low-frequency vibration’ (cf. Friedner and Helmreich 2012). It is known that the act of listening extends beyond the ear, often involving and invoking other senses (vision, touch, thermoception, proprioception) and this way of conceiving amplitude potentially helps expand and acknowledge the sensorial palette.

This approach draws inspiration from Steven Feld’s ‘acoustemology’ (a portmanteau combining acoustics and epistemology), to interrogate ‘what is knowable, and how it becomes known, through sounding and listening’ (2015:12). As Feld recognises however, acoustemology is about ‘knowing-in-action’, and thus inevitably ‘experiential, contextual, fallible, changeable, contingent’ (Feld 2015: 14). I do not pretend to portray these borders as ‘they are’ but rather ‘fathom how they might be alongside (some of) those who [traverse] and compose them’ (Littlejohn 2021:37; see also Helmreich 2015:185). Referring to amplitudes in the plural is thus a way of recognising the incompleteness of the composition and coalescing — subverting even — the perception of frequency into the perception of amplitude (see also the last section where I detail the visual craft of the piece). It is a way of recognising the subjectiveness of who and what was recorded, who was recording, those who now engage with it, and the ‘semiotically and technologically specific articulations’ put forth by recording devices, audio editing tools and listening gear (cf. Helmreich 2016).

I will now turn to the routier activity and introduce Mbaye Sow, who first drew my attention to the role of sound in the context of borders.

 

Routiers

As introduced above, routier is the self-designation of migrant men of African origin who regularly drive overloaded, decades-old vehicles from Europe to West Africa. This is a lonesome and perilous activity that requires a great degree of knowledge and skill — sonic skills included. The rundown cars and the diverse items routiers transport, mostly second-hand objects, some of which are in need of repair, are eventually sold and bartered. As they move south, vehicles and objects go through a ‘transformational trajectory’, with their relative value gradually increasing (Neto & Falcão, 2022). Routiers are also often asked to deliver money remittances and other personal items. Roads, mobile phones, and borders are integral parts of the routiers’ infrastructure. And so are ‘people’ (cf. Simone 2004): the police and the military, various middlemen (transitaires), mechanics, other routiers, migrants heading north and south, diverse clients along the way, and the car buyers. However, routiers never really get to see some of the people that compose this infrastructure. Influenced by Senegalese cultural practices of discretion and protection, many of these people remain only a voice. A glimpse into the routier universe and the circular movements of people, ideas, and objects through the cinematographic account of Mbaye Sow’s life is captured in the documentary film YOON (Neto & Falcão, 2021).

Mbaye Sow worked as a routier for over a decade until Covid-19 dictated the closure of land borders in early 2020. Arriving in Portugal in the late 1980s, he initially worked in construction, then as a petty merchant of African handcrafts. The routier métier eventually became more appealing, offering him relative freedom and the chance to accompany the growth of his children in Senegal. Mbaye himself embodies the border (Mbembe 2019). A border that spans the four thousand kilometres that separate Portugal and Senegal and articulates the two places he calls home. Mbaye is an African immigrant in Portugal and an European emigrant in Senegal. While on the road, he juggles with both European and African identities (and passports).

Beyond fieldwork in Portugal and Senegal, I have travelled twice with Mbaye Sow in different Peugeot 504s from Reboleira, Lisbon’s outskirts, to Pikine, the sprawling (in)formal city east of Dakar. This journey takes about ten days of nearly uninterrupted driving, assuming no other-than-expected surprises, breakdowns, accidents, or hassles. Observations and conversations about the significance of sound for routiers first emerged during these long journeys.

On the first trip with Mbaye, when asked why he did not drown out the monotony and loneliness of the road with some music, he responded that ‘one needs to listen’. Constant auditory awareness is essential. Every sound, every creak, every nuance of the routiers’ infrastructure is potentially meaningful. Mbaye perceived and conceptualised the sounds I was hearing and not hearing in a distinct way from me.

To be a routier involves ‘skilled listening’, a way of knowing that is contingent on the acoustic fields these men encounter (Carlyle & Angus 2013; see also Feld 2015). Verbal information, often carrying road updates and warnings, comes through phone calls and WhatsApp audio messages from friends, acquaintances, and (un)known fellow routiers. The tone and content of this exchange must be carefully considered and dissected. At the same time, the worn-out vehicles in which routiers travel require constant mechanical monitoring; listening to the vehicle helps foresee potential failures and/or manage them. Situated aurality is a multi-faceted necessity. More intriguing, it serves as an indispensable means for navigating the intricacies of border crossings.

A sort of border acoustic literacy is paramount to successfully cross the border. Each border, each checkpoint posits challenges and uncertainties. Mbaye’s sonic skills helped him grasp the amplitudes of each border, that is, how intricate and tense the crossing could be: brace for dog sniffing, prepare for search, vehicle scanning, bribing and questioning, pick up on important conversations, and capture whichever echoes from the other side of the border. Sound ‘(echo)located’ Mbaye in relation to the border and provided a ‘sensory portal’ to the other side (Min 2020:233). Such auditory vigilance informed him of circumstances and prepared him for potential contingencies, deviations from the plan, and allowed him to stay ahead of unexpected hurdles. For Mbaye, for routiers, amplitudes gauged borders. Amplitude reached us and embraced us differently. These diverse experiences and perceptions influenced the exploratory recordings at the composition Border Amplitudes, whose content I now address.

 

Listening to (and seeing) Border Amplitudes

The following section engages with some of the sounds that can be heard throughout the piece. Structured around the four border blocks, and concluding with a note on the visual dimension, it aims to anchor and explore the conceptual potential of border amplitudes.

In the first minute and a half, we traverse from Portugal to Spain, crossing the Ficalho—Rosal de la Frontera border. This crossing is subtly acknowledged by the change in asphalt quality along the road connecting the two countries. It is almost imperceptible. Arguably, there is no causality between greater or lesser (sonic) amplitude and the complexity or straightforwardness of a border crossing. Nevertheless, to think in terms of border amplitudes prompts us to acknowledge the thinness and easiness of this border.

Between roughly minute 1:30 and 4:00, we hear the crossing from Spain into Morocco, across the Strait of Gibraltar by ferry. We become acquainted with a cacophonous background of human whisperers (mostly in Arabic) and the ferry’s informational loudspeakers (in French, English and Spanish). Passengers are asked about their final destination. More important than the answer is the confident tone. (Throughout the piece, diverse languages are heard without subtitles, encouraging the listener to focus on the tonal quality of the voice and how vocalizations convey meaning.) We discern the rhythmic and performative ritual of leafing through passports. The way documents and passports sound can be an indicator of their authenticity — or the lack of it. For the skilled ear, a simple tap against a surface can reveal the consistency and quality of their materiality (cf. Plájas 2024:82). Sounding people and documents amplifies borders.

The sound of stamping marks the entrance in Morocco. Sometimes this occurs while the ferry is still anchored in the Spanish Port of Algeciras, that is, long before traversing the official borderline. Such sounds make the border fuzzier, revealing that more than a line to be crossed, the border is (also) a zone of sonic relations.

Along the straight, the hum and buzz of mobile phones disrupts the airwaves, their radio frequencies interfering with other (recording) devices in a seemingly aimless quest for network connectivity — in which side of the border are we? The sound of network searching is a sort of auditory icon that can be heard throughout the piece. Phone network echolocates us in relation to borders, reminding us of their reach.

From minute 4 to minute 8.30 we prepare to leave the Moroccan Occupied Western Sahara, into Guerguerat Strip and then Mauritania. Inconspicuous radio-frequency waves emanate from huge vehicle scanners. These are denounced by a discrete intermittent high pitch noise. German Shepherds bark in the distance as they sniff people and cargo. These sounds account for how borders ‘touch’ travellers, making state violence haptically evident (cf. Woodward and Bruzzone, 2015). The sounds of German Shepherd’s and vehicle scanners further evince the ‘sedimentation of historical and social forces’ (Kane 2014:68), from the very territorial demarcations to how borders sound — and are sounded. In recent years, western technology and training programmes have supported West African countries’ police and military to enhance the capacity to better sound, surveil and control, regional borders.⁸ Local authorities are expected to follow ‘hegemonic’ ways of listening (cf. Wright 2022) to ‘their’ borders. After all, the Sahel is ‘Europe’s other border’.⁹ Europe is listening too. Are such ‘colonial legacies’ (de L’Estoile 2008) part of ‘what I am not hearing’ (Wright 2022)?¹⁰ Through what is heard and not heard amplitudes impel us to reckon the range of (the control over) this border.

Melodic birds soar freely around the windswept, sandy border, and whose twittering alone is reassuring that it is just another day at the border. Before entering into the Guerguerat Strip, a Moroccan border police officer shrewdly requires passports (again). The tone denounces the end of his authority and a final opportunity for bribery.

Finally, in the last bit of the composition, from minute 8.30 onwards, we engage with the passage between Mauritania and Senegal. The sound of the other side travels towards us before we take the official barge across the River Senegal. Border police whistle frenetically. Different whistle patterns serve to sort people and vehicles according to plates and cargo. A nervous laughter denounces how the passage grates in the bowels of travellers. As Gloria Anzaldúa (1999) once suggested, borders are where worlds ‘grate and bleed’. Sound reveals the depths at which borders ulcerate. But laughter also helps loosen situations. We perceive the bustling, crowded frontier. It physically and psychologically compresses travellers in a nexus of anguish, discomfort, and disquiet. We can literally hear the ‘friction’ (Tsing 2005) against our bodies (and recording devices) — a frictional hiss that enables us to move forward. However, not everything one hears or feels can be fully captured by recording devices.

At last, the creak of a rusty gate marks the end of the crossing.

In Border Amplitudes waveform and spectrogram coalesce. Whereas the waveform essentially depicts pressure or amplitude variations of a sound wave over time, spectrograms provide a more complete (and more visually plastic) picture, showing the signal strength (loudness) over time for various frequencies present in the sound wave. Here, I mirrored the composition’s spectrogram Left and Right channels to replicate and evoke the oscillating nature of the sound wave through amplitude. However, amplitude is now presented through different colours (the brighter the longer, the darker the shorter). Without scale, infrasounds (beneath 20Hz), audible range, and ultrasounds (above 20kHz) are intentionally left to one’s audition and imagination, resulting in an abstract and partial yet granular and volumetric topography of different border amplitudes. In audited borders, where authorities maintain the monopoly on ‘optics’ (cf. Min 2020), such representations become a possible depiction of the border (Neto & Falcão 2023:592).

While these graphics represent the sounds’ ‘narrative and lifespan’ (Rodgers 2011), they also denounce the (mild) post-production the composition has undergone. Equalisation, normalisation, and compression can be aurally and visually apprehended by the skilled ear and eye. The post-production applied to the track was meant to enhance the auditory experience according to listening ‘standards’, that is, to turn the audio legible in a way. In other words, it was adapted to a hegemonic mode of listening (cf. Wright 2022), which nonetheless allows us to explore and account for the experiential and situated nature of border amplitudes. After all, we are not routiers.

 

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^{1. A previous version of this composition was also presented in a listening session at the RAI Film Conference 2023.↩}

^{2. While not everything I remember was captured by the mics, revisiting the recordings made me aware of details I had previously overlooked, forgotten, or probably could not have heard otherwise. Microphones participate in, and reshape the recorded sonic environments (see LittleJohn 2021; Helmreich 2016). The recordings of this composition were captured using diverse mics with bidirectional and cardioid polar patterns.↩}

^{3. Drawing on the work of Pierre Schaeffer, Michel Chion (2019) argues that there are three modes of listening: causal, codal (or semantic), and reduced. Causal listening, the most prevalent way of listening, involves gathering information about the origin of a sound. This mode allows one to identify the source of a sound solely through listening. However, causal listening is often linked to multimodal perception, as we can discern a sound’s source based on prior knowledge, contextual awareness, or visual cues. Chion’s second mode, codal listening, pertains to interpreting language or code, where understanding the tone and intonation of a sound is crucial to grasping its implied meaning. This mode also extends to auditory icons and other sounds that convey specific messages. Finally, reduced listening requires the listener to focus primarily on the sound itself, with cause and meaning taking a secondary role. In reduced listening one might frame the questions of the relationship of sound to meaning differently.↩}

^{4. Hearing and listening are not the same thing. Hearing is a passive behaviour, while listening is an active one (Sterne 2005).↩}

^{5. See Reassemblage (1982, 40 min) by Trinh T. Minh-ha. Min-ha proposes the idea of ‘speaking nearby’ as an indirect form of speaking that reflects upon itself and is capable of coming very close to the subject or topic without, seizing, objectifying or claiming it. I suggest the possibility of expanding this idea to also encompassing the act of listening.↩}

^{6. For a comprehensive approach to these terms and technical aspects of field recording, see Littlejohn (2021).↩}

^{7. ‘Waveform (sound)’, in Federal Agencies Digital Guidelines initiative, US, available on https://www.digitizationguidelines.gov/term.php?term=waveformsound accessed July 5 2024.↩}

^{8. e.g. One recent example is the West Africa Police Information System (WAPIS) Programme, implemented by INTERPOL with funding from the European Union. More info at WAPIS Programme↩}

^{9. Oriol Puig (2020), ‘The Sahel: Europe’s other border’, CIDOB Notes Internacionals 230, March 2020. Available at https://www.cidob.org/sites/default/files/2024-07/NOTES%20230_ORIOL%20PUIG_ANG.pdf accessed in 13 June 2024.↩}

^{10. Through the concept of ‘colonial legacies,’ de L’Estoile (2008) refers to the various meanings and relationships inherited from colonial interactions, which have been reinterpreted, appropriated, negotiated, and contested in postcolonial contexts.↩}

 

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