Sound Reactive Earrings using NeoPixel — a Human Machine Interface case study

10 min readNov 10, 2020

I started working on Human Machine Interfaces back in 2015, with the development of smart gloves for visually impaired people. My journey on HMI and improvements in these systems has been incredible since then. With my inclination to how these HMI can be improved decided to implement some of the strategies in a case study over earing design.

Earings a major point of attention

Human faces and expressions are symbolized by the major points of attraction being on the face and lips. These are even more emphasized with the Ears having earings with decent or good design.

A clean and minimalistic design that not only focuses and emphasizes the face position and expressions but enhances the expressions on the face.

Earings being in pairs have a really good chance of making a connection and making an emphasis on the sides of the face.

Combining and relating them to respond symmetrically is a way of seeking human attention.

Getting The Required Components

NeoPixel LED — Unlike normal LED Strips in which every LED has to address with the same color, I wanted to add a sense of Life into the design, so I used NeoPixel which allows addressing each LED with its own unique color.

SeedStudio Xiao — Seedstudio packed one of their most powerful controller in a tiny form factor, almost the size of a thumb button. This small design form factor is powerful to drive extreme LED units and even displays. Luckily they have embedded and onboard battery port to have an extremely flexible and compact design.

Battery(Optional)- Since during the time I am designing and fabricating this, I don't have any model to wear and show how it looks. I am using a Type-C port to run the circuit.

Additional Maker Tools — 3D Printer, Wire Cutter, Soldering Kit.

Design Psychology

Total number of LED — 8

Color Support — 16M Colour combination

Types of Blinks Available —

Alternate Profiling — Switching between different colors and skipping an LED in between.
Swift Motion Trail — Smooth Motion of one guide light and others Following the guiding light.
Notification Circle — Rapid and Responsive Motion of LED color symbolizing a rapid and instant change in the profile.
Continous Fading — Irrespective of the input the color shift varies and continues to fade In and out without any particular pathway or direction.

I took some reference studies fromhttps://www.ledinside.com/ for my lighting Inspiration

Lighting modes & subjective impressions (Lighting Psychology)

For most lighting practitioners, the phrase “Lighting psychology” immediately brings to mind the work of the late John Flynn. Flynn examined the human response to lighting by studying an array of subjective impressions related to architectural settings, to determine which of those impressions were affected by changes in the lighting stimulus.

For some impressions, changes in the lighting produced significant changes in the response — impressions such as spaciousness, visual clarity, privacy, pleasantness, relaxation, complexity. By linking lighting to these impressions, Flynn demonstrated that architectural lighting plays a much more significant role in the human experience than simply as an enabler of task performance.

In addition to studying human responses to lighting, Flynn also sought to understand the nature of the stimulus that produced those responses. Which attributes of lighting in space seemed to relate to the various impressions that could result? Flynn identified four of these attributes, which he called the “lighting modes.” The modes each express a continuum of changes in lighting between two extremes. Flynn’s lighting modes express the basic parameters of lighting which designers manipulate in creating the environments they desire — bright/dim, uniform / non-uniform, central / perimeter, and warm/cool. Flynn’s message was that as you change the lighting stimulus along these dimensions, you will produce changes in the human response in terms of the impressions that are reinforced. And — importantly — these responses will occur whether you planned for them or not.

The practicality of Flynn’s work for lighting designers resided in his attempts to link the lighting modes to the human subjective responses. To reinforce a particular impression in a space, a designer could focus on certain aspects of the lighting mode descriptors in designing the lighting system. For example, the designer could reinforce a feeling of relaxation by employing non-uniform lighting on the perimeter room surfaces from warm-tone light sources. Uniform lighting on the perimeter room surfaces reinforces an impression of spaciousness. Although the design guidance that resulted from the Flynn work is qualitative in nature, many practitioners have found the linkages between the lighting modes and the subjective impressions to be a useful characterization of the stimulus and responses to lighting that move beyond task performance.

Making sense and being involved (Environmental Cognition)

Whereas Flynn’s research focused specifically on lighting, other researchers with no particular interest in lighting examined the broad range of human responses to environmental stimuli. From the field of environmental cognition, the work of Kaplan and Kaplan provides important insights of relevance for lighting practice. These researchers sought to understand the factors that drive human preference for environments. One factor that emerged from their research is the desire to make sense of our surroundings. According to the Kaplans, when we are exposed to a new environment, finding a cognitive match for the environment in our memory is a primary goal, as a way of helping us to interpret and understand the new environment.

Often we enter a new environment that has many similarities to other spaces we have experienced. The high degree of familiarity elicits a pleasant, comfortable reaction as we immediately can make sense of the setting. Other times we enter an unusual space that poses an entirely new experience, and we find it disconcerting as we struggle to make sense of the environment. The fundamental human need to make sense of our environment explains both of these disparate experiences, according to the Kaplans’ research.

But what about the WOW factor in a new environment? We have all experienced a time when we encountered something completely new, but somehow the uniqueness and unfamiliarity were stimulating and exciting. And no doubt we share the common experience of entering a highly familiar space and finding that its very familiarity produces a low preference — “Oh please, not another drab hotel seminar room with boring uniform lighting!” In this case, highly familiar leads to low preference. Clearly, a second factor must interact with our desire to make sense of the environment in determining our preference.

The factor that supplements our drive to make sense of our environment, according to the Kaplans, is a desire for involvement with the environment. We want the environment to be interesting, we want it to invite us to explore and engage, we want a sense of complexity and mystery. This underlying purpose of involvement makes some novel environments seem exciting rather than just plain weird or overwhelming, and it also makes some very familiar environments seem just too uninteresting to us.

A summary of Kaplan's preference chart. (Photo Courtesy of LiteControl)

Kaplan and Kaplan use two keywords to capture the essence of these environmental aspects that drive our preference: coherence and complexity. Coherence relates to our ability to make sense of the environment — does the environment provide us with cues that enable proper interpretation? Are there enough familiar elements in the environment that allow us to make mental matches to our prior experiences? If we can quickly make sense of an environment that is coherent, then the likelihood that we will develop a positive preference for the environment increases.

Although Kaplan and Kaplan were environmental psychologists who primarily focused on outdoor environments in their research, they recognized the connections between coherence and lighting effects. Consider this quote:

“It is also important that a change in texture or brightness in the visual array is associated with something important going on in the scene. In other words, something that draws one’s attention within the scene should turn out to be an important object or boundary. . . If what draws one’s attention and what is worth looking at the turn out to be different properties, then the scene lacks coherence.” (Kaplan 1988, p. 49)

So a brightness emphasis that helps to make sense of an environment increases its coherence, making it a more pleasant space. Conversely, a change in brightness that is unrelated to anything important in the visual scene creates a lack of coherence, makes it more difficult to properly make sense of the space, and thereby reduces a person’s preference for space.

Coherence is critical, but a space that is completely coherent but overly simplistic fails to provide the stimulation and involvement that we desire. Complexity in the environment relates to our innate desire to engage, to be active participants with our environment. This cognitive link between complexity and preference also occurs in the realm of music appreciation. In his excellent book, This is Your Brain on Music, Levitin writes:

“When a musical piece is too simple we tend not to like it, finding it trivial. When it is too complex, we tend not to like it, finding it unpredictable — we don’t perceive it to be grounded in anything familiar. Music, or any art form for that matter, has to strike the right balance between simplicity and complexity for us to like it.”

Apparently, our desire for a certain level of complexity holds for a wide range of stimuli, whether a musical piece or an architectural environment. We desire coherent environments that we can easily interpret, while at the same time we desire an appropriate level of complexity to keep us interested.

The third thread: Pleasantness, arousal, and control (Emotional Response)

From Flynn, we see a thread of thought that describes the lighting stimulus in terms of some basic modes of variations and links those variations to the human response of subjective impressions of environments. From Kaplan and Kaplan, we weave in a thread that characterizes the stimulus along with the parameters of coherence and complexity and relates those parameters to the response of human preference. And for our third thread, we look to the work of James Russell, whose career has been devoted to understanding human emotional development and response.

Kaplan and Kaplan stimulus along with the parameters of coherence and complexity. (Photo Courtesy of LiteControl)

In Russell’s model, the primary emotional responses to the environment determine the behavioral responses. According to this model, the human sensory systems process the environment and characterize the relationships between various aspects of the stimulus. This sensory input combines with personality characteristics to produce primary emotional responses in three areas — the pleasure that a person finds in the environment, the amount of arousal or stimulation that the environment provides, and the extent of dominance or control that people feel they have while in the environment.

The dominance response has some fascinating implications for lighting, as it depends on how much control we feel we have over the environment compared to how much we feel the environment controls us. The connections to automatic vs. manual lighting controls are intriguing. We’ve seen studies that document greater energy savings when people have manual control, and we all know stories of negative reactions to fully automatic controls. We may be able to weave this thread together with the Kaplan’s “desire for involvement” thread to derive a general principle about human reactions to environments. But, that exploration is beyond our scope for now.

Classification of Russell’s theory on human reaction to the environment. (Photo Courtesy of LiteControl)

Ultimately, Russell settled on the pleasure and arousal emotions as the two primary ways that we respond to environments. In Russell’s view, whenever we enter a new environment, we quickly place it into one of four quadrants that are defined by the two axes of pleasure and arousal. This structure is shown in the figure below.

While Russell’s initial work related directly to architectural environments, he later explored human emotional response to all types of stimuli. His model has been used in a variety of industries and applications, from advertising studies to experiments in childhood development. (In fact, his seminal paper in the Journal of Research in Personality titled, “Evidence for a three-factor theory of emotions,” was recognized by the journal as one of the ten most frequently cited papers in its 43-year history.) So it seems that these emotional responses are fundamental to the human condition.

Russell argues that our emotional response to a stimulus along the two dimensions of pleasure and arousal is a single, integrated response rather than two distinct responses. The words we use to describe spaces reflect this sort of integrated response. An environment that we call, “stimulating,” is one that is both arousing and pleasant, while one that we call, “tense,” is also arousing but a bit unpleasant. A “relaxing” space rates low on arousal but relatively high on pleasure, while a “dreary” space is also low on arousal but elicits a response that is low on pleasure as well.

Final Earring Design and Implementations