Category: Psychoacoustics

  • Listening Between Worlds: Dr Ximena Alarcón on Deep Listening and Sonic Migrations

    Dr Ximena Alarcón

    Migration is often described through borders, journeys, and distances travelled. People leave cities, cross countries, settle elsewhere, and gradually build new lives. Less often do we ask what migration sounds like. Yet movement between places changes more than physical location. Familiar sounds disappear from everyday life while new ones slowly become woven into routine experience. Voices remain in memory long after people and places have gone, and certain sounds can unexpectedly return us somewhere we thought we had left behind.

    During an online guest lecture, Dr Ximena Alarcón explored these less visible experiences through sound, asking whether listening might reveal dimensions of migration that geography alone struggles to capture. Drawing on her own experiences of moving from Colombia to Europe, alongside years of artistic and research practice, she explored how listening can become a way of understanding relationships between people, places, and memory.

    Dr Alarcón is a sound artist, researcher, and Deep Listening practitioner whose work combines collaborative performance, sound art, memory, and digital technologies. Across these projects and reflections, one idea repeatedly surfaced: listening is not simply an act of hearing sounds that already exist around us. It can also become a way of tracing experiences, understanding relationships, and making sense of where we belong.

    Many of these ideas first developed through an apparently ordinary experience. After growing up in Bogotá and later encountering underground transport systems in European cities, Alarcón became increasingly interested in the environments created by these systems. Most people barely notice them. Announcements repeat endlessly, trains arrive and disappear, and routine eventually turns entire spaces into background activity. Daily commuting often becomes something we stop consciously hearing. Yet beneath that familiarity, people continue forming subtle relationships with the spaces around them, carrying emotions, frustrations, routines, and memories through these environments day after day. Alarcón became interested in what kinds of traces these repeated experiences might leave behind.

    This question developed into Sounding Underground, a project exploring underground systems in London, Mexico City, and Paris. Participants recorded journeys, selected sounds they considered meaningful, and reflected on the experiences attached to them. Rather than documenting transport systems themselves, the project explored relationships formed through listening.

    “What memories have people when they listen during routine journeys?”

    Responses revealed something surprising. Participants recognised common rhythms and textures across different cities while also identifying details that felt distinctive to each place. One participant described experiencing the three underground systems as though they formed a single connected network rather than separate environments. Sounds that would usually disappear into the background of everyday life suddenly felt more intimate. Mechanical noises, station announcements, and passing voices acquired emotional significance, becoming linked with memory and familiarity in ways that might otherwise remain unnoticed.

    Questions that initially centred on transport systems gradually grew more personal. Listening repeatedly to memories of movement raised another question that redirected Alarcón’s work entirely: “I would like to listen to my own migration.” Attention moved away from cities themselves and towards the experiences carried through them. The question was no longer simply how environments sound, but how memories, identities, and relationships continue shaping listening long after movement has taken place. This transition led Alarcón towards Deep Listening, a practice developed by Pauline Oliveros that encourages expanded awareness of sound, body, memory, and environment.

    Deep Listening extends beyond identifying sounds within a space. Listening becomes connected with silence, bodily awareness, dreams, movement, and relationships with others. Alarcón described keeping dream diaries as part of this process, recording fragments of dreams before they disappeared into waking life. Listening was no longer directed only towards external environments. It became a way of tracing relationships between memories and experiences that might otherwise pass unnoticed. Migration consequently began to appear as something more complex than movement between locations. Memories from different places continue existing alongside present experiences, while voices from the past remain present within current surroundings. Different versions of ourselves emerge over time rather than simply replacing one another.

    Language became an important part of this exploration. During the lecture, Alarcón reflected on the experience of moving between English and Spanish, describing how speaking different languages can sometimes feel like moving between different versions of oneself.

    “When you speak more than one language, you start to create a different personality when you switch between languages.”

    Many people who speak more than one language immediately recognise this feeling. Words change, though something else changes as well. Rhythm changes, gesture changes, and emotional expression often shifts in subtle ways. Certain ideas suddenly become easier to express while others seem to disappear entirely. Alarcón described this through the idea of the “nomadic voice”, suggesting that migrants often inhabit spaces that are neither entirely one place nor another. Instead, memories, identities, and experiences overlap and remain in motion, creating what she described as in-between spaces.

    Questions about memory and identity eventually expanded beyond individual experience. If listening could reveal something about personal migration, could it also create meaningful connections between people separated by geography? This question shaped projects such as Letters and Bridges and Migratory Dreams, where participants in different countries exchanged letters, shared dreams, recorded sounds, and developed collaborative sonic performances across distance. Unexpectedly, participants often described feeling close to people they had never physically met.

    One of the most memorable moments emerged during Migratory Dreams. Participants in Bogotá perceived London as sonically dense and heavily urban. During performances they instinctively introduced sounds of nature, almost as if attempting to return something they felt migrants living in London had lost. Across continents, participants were not simply exchanging sounds or creating performances. Listening had become a way of caring for distant people through shared experience.

    Although these projects emerged through experiences of migration, the ideas discussed throughout the lecture extend far beyond migration itself. Sound design often focuses on realism, immersion, and technical precision, yet Alarcón’s work suggested broader possibilities. Sound can preserve memory, support identity, and create relationships between people separated by distance.

    Migration, in this sense, may involve more than moving between places. Physical journeys eventually end, yet the quieter journeys shaped by memory, identity, and listening often continue long afterwards. Alarcón’s lecture suggested that people do not simply travel across spaces. They also continue travelling through experiences, relationships, and sounds that remain with them long after they arrive.

  • Understanding Binaural Hearing: Insights from Professor Jens Blauert’s Guest Lecture

    Binaural hearing is fundamental to how we perceive sound in space, influencing everything from daily interactions to the way we experience music, film, and interactive media. In a compelling online guest lecture, Professor Jens Blauert, a leading researcher in psychoacoustics and spatial hearing, provided an in-depth exploration of the principles behind binaural perception. His extensive research has shaped the fields of spatial audio, binaural recording, and 3D sound reproduction. Best known for his influential book Spatial Hearing: The Psychophysics of Human Sound Localization, his insights are particularly valuable for sound designers working in film, virtual reality, game audio, and immersive media.

    Professor Jens Blauert

    The Relationship Between Physics and Perception

    One of the key distinctions Professor Blauert made in his lecture was the difference between the physical properties of sound and auditory perception. Sound, as a physical event, consists of mechanical waves traveling through a medium, whereas auditory perception arises when the brain processes these waves, constructing an auditory event. This distinction is essential for sound designers because reproducing the physical properties of a sound does not guarantee that it will be perceived as intended. The auditory system is not a passive receiver but an active interpreter, reconstructing sound based on cues such as timing, intensity, and spectral content.

    How Humans Localise Sound

    A major focus of the lecture was the way humans determine the position of a sound source. Interaural time differences occur when a sound reaches one ear before the other. The brain interprets this difference as an indication of direction, which is particularly useful for localising low-frequency sounds below 1.5 kHz. At higher frequencies, interaural level differences become more significant, as the head acts as a barrier, creating differences in loudness between the ears. Another critical factor in sound localisation is spectral filtering by the outer ear. The pinnae modify the frequency spectrum of incoming sounds depending on the direction from which they arrive, helping the brain determine elevation and distinguish between front and back sound sources.

    For sound designers, understanding these cues is essential when working with spatial audio and binaural rendering. In virtual reality and gaming, the careful manipulation of interaural time differences and interaural level differences ensures that sound sources are perceived as truly occupying a three-dimensional space.

    The Role of Other Sensory Inputs

    Spatial hearing is not an isolated process but is influenced by other sensory inputs, particularly vision and proprioception. Professor Blauert discussed the ventriloquism effect, where conflicting auditory and visual information results in the brain prioritising vision. This is why, in a film, dialogue appears to come from the mouth of an on-screen character, even if the sound is emitted from off-screen speakers.

    Head movements also play an essential role in localisation, as the brain refines auditory perception based on changes in sound cues over time. In virtual reality, integrating real-time head tracking with binaural audio processing enhances immersion, ensuring that spatial cues remain accurate as the listener moves.

    Reverberation, Reflections, and Spatial Awareness

    Reverberation and sound reflections also shape spatial perception. In natural environments, sounds bounce off surfaces before reaching the ears, adding information about distance and space. Early reflections, which arrive within the first few milliseconds, provide cues about room size and material properties. Late reverberation contributes to the sense of spaciousness and immersion.

    For sound designers, controlling reflections is crucial for shaping an environment’s acoustics. Artificial reverberation can make a space feel larger, more intimate, or more diffuse, but excessive reverberation can blur spatial cues, reducing intelligibility.

    The Cocktail Party Effect and Binaural Signal Detection

    The lecture also explored how the auditory system processes multiple overlapping sound sources. One of the most fascinating aspects of binaural hearing is the ability to focus on a particular sound source while filtering out others, a phenomenon known as the cocktail party effect. When multiple sounds arrive at the ears, the brain can separate them based on spatial location and timbre.

    People with hearing impairments, especially those with asymmetrical hearing loss, struggle in noisy environments because they lose this spatial filtering ability. For sound designers, this principle is fundamental to mixing dialogue, music, and effects. Ensuring that critical sound elements remain perceptually distinct is essential for clarity and intelligibility.

    Professor Blauert also explained that binaural perception is not only responsible for spatial hearing but also plays a role in reverberation suppression and timbre correction. When listening with both ears, the auditory system can reduce the perceived reverberation of a space, making sounds clearer. It can also compensate for frequency distortions caused by reflections. A simple experiment demonstrates this effect: if a listener closes one ear while in a reverberant environment, the space sounds more echoic, and the timbre of sounds changes. When both ears are used, the brain naturally suppresses excess reverberation and restores a more natural balance.

    For sound designers, this means that spatial mixing must account for how the brain processes sound, ensuring that artificially introduced reverberation does not interfere with localisation or speech intelligibility.

    Applications for Sound Design and Spatial Audio

    The principles covered in this lecture have direct applications in binaural audio, 3D sound design, and immersive media. Headphone-based binaural recordings create highly realistic spatial experiences, making them ideal for virtual reality, augmented reality, and gaming. In film and theatre, spatial mixing techniques enhance realism and guide audience attention. In architectural acoustics, an understanding of how reflections shape perception is crucial for optimising venues for speech clarity and music performance.

    The research presented by Professor Blauert also informs the development of hearing aids and assistive listening technologies, improving speech intelligibility for individuals with hearing impairments.

    Final Thoughts

    Professor Blauert’s lecture reinforced the importance of understanding how humans perceive sound rather than focusing solely on its physical properties. For sound designers, the key takeaway is that perception determines how spatial audio is experienced. A strong grasp of binaural hearing principles enables the creation of immersive, natural, and convincing soundscapes, ensuring that audio enhances storytelling, gameplay, and user experience.

    As the demand for interactive and immersive media grows, these concepts remain essential tools for crafting engaging auditory environments.

  • Understanding Aural Architecture: A Guest Lecture with Dr Barry Blesser and Dr Linda-Ruth Salter

    The experience of space is often thought of as a visual phenomenon, but our understanding of where we are is deeply tied to sound. In a thought-provoking guest lecture, Drs Barry Blesser and Linda-Ruth Salter explored the concept of aural architecture, discussing how sound shapes our perception of space and influences human interaction. Their insights challenge conventional thinking about hearing and space, bridging disciplines from acoustics and cognitive science to architecture, social anthropology, and Sound Design.

    D rBarry Blesser

    About the Speakers

    Dr Barry Blesser is a pioneering researcher in audio technology and spatial acoustics, best known for his contributions to digital reverberation and sound processing. As one of the key figures in early digital audio, he played a central role in the development of the first commercial digital reverb unit in the 1970s. His expertise spans psychoacoustics, signal processing, and the experiential aspects of sound perception. His book Spaces Speak, Are You Listening? (co-authored with Dr Linda-Ruth Salter) explores the relationship between sound and space, shaping discussions on aural architecture.

    Dr Linda-Ruth Salter is an interdisciplinary scholar whose work explores the intersection of space, culture, and human perception. With a background in philosophy, social science, and design, she has contributed to research on how architecture and auditory experiences influence human cognition. Her collaboration with Dr Blesser in Spaces Speak, Are You Listening? examines how sound and built environments shape social interactions and emotional responses.

    The Concept of Aural Architecture

    Aural architecture refers to the way sound interacts with a space and how we, as listeners, interpret and experience that interaction. Drs Blesser and Salter highlighted a crucial distinction: hearing space is not the same as hearing sound. While we might assume that knowing where we are is intuitive, the lecture invited us to consider a deeper question: how do we truly know where we are?

    Using historical and experimental examples, the speakers demonstrated that sensory input—especially sound—plays a vital role in spatial awareness. One striking example involved sensory deprivation experiments from the 1950s, where participants placed in silent, isolated environments began to hallucinate within minutes. This underscores how critical sound is for maintaining a coherent sense of place.

    For Sound Designers, this concept is fundamental when creating immersive experiences in film, games, and virtual reality (VR). In horror sound design, for instance, silence can be just as powerful as sound. By gradually removing background noise and narrowing the listener’s sense of space, Sound Designers can create an unsettling effect that plays with the brain’s need for spatial awareness.

    The Role of Sound in Spatial Perception

    Different senses contribute in unique ways to our understanding of space, but hearing is particularly powerful. Unlike vision, which depends on illumination and line of sight, sound travels around obstacles, fills enclosed areas, and provides constant feedback about an environment. This ability to hear space allows us to determine room size, surface materials, and even the presence of unseen objects.

    Drs Blesser and Salter illustrated this with a compelling thought experiment: if you were placed in a completely dark room but could still hear, you would likely be able to infer the shape and size of the space just by listening to how sound behaves. This principle is at the core of aural architecture, influencing everything from concert hall design to everyday experiences in urban and domestic settings.

    In Sound Design, this understanding is crucial when designing game audio environments. Many modern game engines use real-time spatialisation techniques such as occlusion filtering, where sounds are dynamically muffled or altered when obstructed by walls or objects. This not only makes the soundscape more realistic but also enhances gameplay by providing the player with important auditory cues.

    Another example is reverberation in post-production for film and television. When mixing dialogue recorded on a sound stage, Sound Designers often add convolution reverb to match the acoustics of the scene’s visual setting. Without this adjustment, the dialogue may feel disconnected from the environment, breaking immersion.

    The Impact of Culture and Cognition

    The lecture also explored cultural and cognitive aspects of auditory perception. Different cultures interpret sound in diverse ways, and our brains continuously rewire themselves based on how we use our auditory system. For example, musicians who have trained their ears for years can detect subtle variations in acoustics that others might not even notice. Similarly, some blind individuals develop an advanced ability to hear space through echolocation, using sound reflections to navigate their surroundings.

    The speakers pointed out that aural architecture is as much a cultural phenomenon as it is a scientific one. In some societies, specific sounds become deeply symbolic. The resonance of a cathedral, for instance, has historically been associated with religious experience, while the chime of a village bell once defined local identity in 19th-century France.

    For Sound Designers working in interactive media or theatre, understanding cultural soundscapes can enhance authenticity and immersion. When designing audio for a historical drama, for instance, awareness of period-accurate materials, such as wooden floors, stone walls, or open landscapes, allows designers to recreate accurate acoustic reflections, enhancing immersion.

    The Changing Nature of Soundscapes

    With advancements in technology, our relationship with sound and space is evolving. Modern electronic devices create virtual auditory environments that can transport our minds elsewhere, detaching us from our physical surroundings. The ubiquity of headphones, for example, allows individuals to curate personal soundscapes, but it also leads to functional deafness—a state where people can no longer hear the sounds that define their immediate environment.

    For Sound Designers, this has significant implications in VR, AR, and immersive media. One example is the use of dynamic object-based audio, such as Dolby Atmos or Ambisonics, which allows sounds to be placed in 3D space and adapt to listener movement. This ensures that spatial relationships between sound sources remain consistent, even as the user moves through a virtual or augmented environment.

    Another example is binaural audio mixing, often used in ASMR, virtual museum guides, and 3D audio storytelling. By recording with a dummy head microphone, Sound Designers can capture the way sound naturally interacts with human ears, providing a hyper-realistic listening experience that can transport users into another environment.

    The Responsibility of Aural Architects

    Drs Blesser and Salter concluded with a call for greater awareness in design, urging architects, engineers, and urban planners to consider aural architecture in their work. They introduced the concept of aural empathy—the ability to design with an awareness of how sound affects human experience.

    A key takeaway from the lecture was that sound is not just a by-product of space; it is an integral part of how we experience it. Thoughtfully designed spaces take into account how soundscapes influence mood, communication, and social interaction.

    For Sound Designers, this means thinking beyond just what a sound effect should be and instead considering how it should be experienced within a space. Sonic accessibility is another important aspect—for instance, ensuring that spatialised audio cues in video games or public environments assist users with different hearing abilities.

    Final Thoughts

    This lecture provided a fascinating lens through which to examine space, demonstrating that aural architecture is not merely a technical concern but a fundamental aspect of human perception. By incorporating auditory awareness into design, we can create richer, more engaging environments that truly reflect how people experience the world.

    For those working in Sound Design, these ideas reinforce the importance of treating space as an active element in an auditory experience. Whether designing immersive film soundtracks, crafting realistic game environments, or developing innovative AR applications, an understanding of aural architecture can elevate the quality of sound experiences.

    The next time you step into a space, take a moment to listen to it. What can the sound tell you about where you are? The answer may be more complex than you think.