MBTA Accessibility Workshop

Beaconing: when a system offers information to users

Puddling: when sonic information is contained within, and only within, a distance appropriate to those who need the information

Information Equivalency: information in different forms (visual, tactile, sonic) remain distinct from each other, yet allow equal access to information

The most important concept gathered from this workshop was how many people depend on ambient sounds of public transport for their spatial models of public space. Previous art installations that promote dramatic changes in sonic consumption are often at odds with accessibility-needs of certain patrons.

Read the full notes below:MBTACrossingWork_notes.png


Sound and Memory: Sketches

To first understand how perception of sound and memory of that sound, our team began to take walks around the Northeastern University area, near Ruggles Station. We then traced our path on an aerial map and recounted when we remember certain sounds sources being perceivable and which weren’t.

We then took a survey of patrons currently inside and sonically-removed from Ruggles Station and asked them what they heard:

odonnel_Acoustic_Memory 7.png

Interesting to note that people inside Ruggles Station only picture themselves near the transportation they arrive to the station on most frequently. However, we only interview people in the passageway, of which most of our sound experiments with Bruce Odland and Sam Auinger took place. People are able to hear a variety of sounds in Ruggles, yet they aren’t committed to memory as easily as the sounds of transportation devices.

Further, we continued our introspection studies to draw what we called a “sonic chamber” or the perceived volume of space that a sound is contained within. Over top of our spatial mental model of Ruggles, each of us drew chambers for different sound sources we remembered from our day prior in Ruggles. The result is a perspective of space that is created by perception of sound.


The overlap and lack of overlap allowed us to analyze space in a way that permitted sonic interventions that would not interrupt accessibility needs of those patrons who depend on sonic stimuli.

Sonic Intervention-01.png

Sonic Commons Project: Sound and Memory

For the Sonic Commons project, students should analyze a sonic phenomena from observations and experiences in the space at Ruggles Station.

“What does it mean to explore a phenomenon? An explanation is never the phenomenon itself, but only a refracted image of it, like looking at a scene through a prism.” — Barry Blesser and Linda-Ruth Salter, in Spaces speak, are you listening? : experiencing aural architecture

Ruggles Station – aerial view from the south

While visiting the site, we passed an escalator that connected the domed tunnel passageway and the below-ground bus bay (seen on the right side of the station in the picture above). This escalator, operating normally, emitted a distinct tone from some part of the motor, I’m assuming. While not a pure tone, it was an observable standing wave amongst the clamor of socialization and transit. After experiencing the area outside the station and coming back to the same place, I could hear the escalator’s unique standing wave from a greater distance and with more clarity, despite the dynamic sonic environment attempting to mask it. This lead to a fascination with a psychological understanding of sonic memory and it’s relation to architecture.

Psychology of Sonic Sensation, Perception, and Memory

Human Memory (2003), 2nd Ed.
Ian Neath & Aimée M. Surprenant

Chapter 4: Working Memory

Baddeley & Hitch (1974) Working Memory Model

Working Memory Model: A Central Executive function controls attention (voluntary processing of stimuli), learning, and retrieval functions.

  • Phonological Loop: Back and forth between Phonological Store and Articulatory Control Process.
  • Phonological Store: Short-term aural memory, said to only keep information for ~2 seconds without rehearsal
  • Articulatory Control Process: A repetition or refreshing process that rehearses/refreshes phonological store
  • Episodic Buffer: A theoretical addition to the Working Memory model; a system that may utilize multiple sensory inputs to support learning and recall.

theorized to help create hierarchy and meaningfulness in stimuli perception and memory recall

Chapter 5: Perspectives on Processing

Context-Dependent Memory: Recall of long-term memory occurs more accurately when context of rehearsal matches context of recall.

  • Context can be any environmental factor (light, volume, location) or additional stimuli.

State-/Mood-Dependent Memory: matching states (pharmological, stress) or matching moods both support accuracy in recall of long-term memory.

Chapter 12: Reconstructive Processes in Memory

Schema: an organized knowledge structure that reflects an individuals knowledge, experience and expectations about some aspect of the world. These are parts that define schemas:

  • Schemas represent experiential knowledge, and are dynamic with additional experiences.
  • Schemas can represent multiple knowledge levels, from concrete objects to complex social situations
  • Schemas can be nested and/or related, such as a schema about ice cream within a schema about commercial transactions (to buy ice cream)
  • Schemas information is very general, so they also have variables. A coffee schema temperature variable is usually hot, but it is not uncommon to experience iced coffee.

Sensation and Perception (2010), 8th ed.
E. Bruce Goldstein

Chapter 11: The Sound Stimulus

sound can have two definitions: a physical definition of sound is a pressure change in a medium; a perceptual definition of an experience when hearing stimuli

Sound as Pressure Changes

  • A movement of a speaker’s diaphragm causes rapid changes in volume. Outward motion pushes air together (higher pressure, or condensation); inward motion creates new space for air molecules to spread to (lower pressure, or rarefaction).
  • It’s the systems of pressure that move away from the speakers, not the air particles themselves

Perceiving Sound

  • A Decibel (dB) describes a physical measure of sound; Loudness describes a physiological sensation of sound. Loudness is a combination of both pressure changes and frequency.
  • Pitch (perceptual ranking of sound on a musical scale) is closely related to a wave’s frequency.
  • Timbre (or quality of sound) depends on relative strength of harmonics (various pure tones that overlap in a complex tone) as well as attack/decay of sound.
  • Aperiodic tones, those that do not repeat pressure changes (unlike musical tones), are even more complex yet.

Central Auditory Process in Brain

  • More areas of your brain are activated by aperiodic complex sounds than by pure tones, suggesting different areas of the brain aid in perception of different qualities of sound (decay rate, pitch, frequency, etc).
  • Different neuron pathways are activated depending on the perceptual usage of sound (what pathway identifying sounds is a separate neuron chain from where pathway spatially locating sound).

The Auditory Cortex is Shaped By Experience

  • Training of any kind (music, active listening, etc) can shape neuron connectivity within brain in two ways: formation of more connections, and more sensitive connections. Musicians use more of auditory cortex to perceive piano notes than non-musicians. Effects can be seen in as few as seven “learning” encounters with a stimuli of choice.

Chapter 12: Sound Localization and Auditory Scene

Auditory Localization: perceiving objects that emit sound at different spatial locations

Auditory Space: the perception of volume/space/architecture from sound information

Three dimensions of sound localization

  • azimuth: left/right sound dichotomy
  • elevation: up/down sound dichotomy
  • distance: near/far sound dichotomy

The cochlea (inner ear location of sound receptors) transmits information on pitch and timbre; localization requires location cues from sound interacting with the head and ears.

Binaural cues

  • Inter-aural Time Difference: time differs for sound to reach each ear (unless directly in front or behind listener). Helpful for low-frequency sound localization.
  • Inter-aural Level Difference: Head acts like a buffer and pressure perceived differently in each ear. Helpful for high-frequency sound localization. (See diagram)
An acoustic shadow is created by higher frequency sounds, not so much with lower frequency sounds.

Monaural cues

  • ITD and ILD still create a cone of confusion, or localization ambiguity, for the elevation dimension of sound. Monaural cues help establish elevation.
  • The shape of your pinna and ear canal (outer ear) reflect sound (and thus change frequency of stimuli) in unique ways depending on elevation.

Perceptual Organization of Sound

  • Auditory Scene Analysis: Separating perceptions of stimuli into being emitted by unique sources
  • Auditory Grouping: Peceptual organizing of sounds based on similarity or distinctiveness or dynamically of location, timbre, pitch, etc
  • Experience and memory can shape perception. If a melody is split between various octaves, those with a familiarity of the melody can still pick it out.

Sound and Architecture

Spaces speak, are you listening? : experiencing aural architecture
by Barry Blesser and Linda-Ruth Salter

1 Introduction to Aural Architecture

  • acoustical awareness is a skill everyone possesses, but often isn’t aware of it’s role in our lives
  • when we clap our hands (sonic event) a wall reflects an echo (passive acoustic object, the wall)
    • The distance to the wall determines the delay for the arrival of the echo, the area of the wall determines the intensity, and the material of the wall’s surface determines the frequency content. These physical facts relate only indirectly to perception. Our auditory cortex converts these physical attributes into perceptual cues, which we then use to synthesize an experience of the external world.
  • architecture can cue emotions, associations or social meaning
    • like dampening drapes for a reading room, or marble floors in a lobby for announcing arrival of guests
  • sensory anthropology studies how sense-usage results in meaning of perceptions across cultures and despite biology
  • aural architects focus on the space changing the physical properties of sound waves; acoustic architect focus on the way that listeners experience the space (subjective, dynamic).
    • it is for this reason that aural architects are often not people, but sociocultural forces influencing design and perception


  • Aural experiences are fleeting
  • Language for describing sound is weak and inadequate
  • Modern culture places little value on the importance of hearing/art of auditory awareness
  • Aural architecture is not generally recognized in intellectual inquiries, nor taught in academia

“ When fused together into a single concept, however, the marriage of aural architecture and auditory spatial awareness provides a way to explore our aural connection to the spaces built by humans and to those provided us by nature.

Within my research, I discovered that publications that connect sound and architecture are few and far in between. The two types of buildings that have information concerning their intersection are auditoriums for concerts and churches. Barry Blesser and Linda-Ruth Salter suggest that churches are constructed to permit sonic reflection and resonance to symbolically reference a higher power.

For the purposes of my research, I continued to treat the sonic phenomena from religious architecture as a explanation of the space, and to further study how sonic phenomena gives rise to the programming of the space. Below is a concept map connecting sound to religion.

Concept Map concerning Sound and Religion
Concept Map concerning Sound and Religion

From a variety of academic, philosophical, theological and fact-weary sources, I discovered many religions describe their higher power(s) in a sonic capacity, and some even constrict or ban its visual imagery. Similarly, science (if that is your religion) begins to have difficulty identifying the building blocks of the universe. Many phenomena are not physically observable, but it is changes from one state to another let us know things/matter exists. And after all, sound is by definition changes in pressure.

My research suggests the following be taken into account when developing a sonic understanding of architecture:

  • What makes an architectural space religious, sonically?
  • Is Ruggles Station a sonically religious space, and if so, what are the tenants of its religion?
  • Does architectural space dictate acoustic phenomena or does acoustic phenomena give rise to our perception of architectural space?

To gain a better understanding of sonic information processing within architectural spaces, my data collection methodology will begin with interviews. Subjects will be divided into two groups: (1) active stimuli experience, or those sonically near Ruggles Station and (2) reconstructed stimuli experience, or those sonically removed from Ruggles Station.

From there, the subject matter brought up by both groups will be explored with binaural microphone recordings of Ruggles Station. Discrepancies between sonic information and location of listening (or reconstructing sonic memory) will be the focus of my analyzation.