In the Spring of 2024, Cambridge Audio took me on as an intern for six months. My challenge was to improve the enormously popular and critically appraised P100 headphones they had just released.
The P100s were a cut above the competition in so many ways - they sounded far better and the battery lasted much longer. However, these headphones left something to be desired in terms of comfort and stability. The premium quality audio drivers nudged the P100s towards the heavier side, and Cambridge Audio, being traditionally an ‘audiophile’ Hi-Fi brand, had not anticipated for the many ways people use headphones outside the stationary comfort of their listening rooms - such as for walking the dog, running, going to the gym, long plane flights. The headband would begin to hurt after an hour of wearing, and the earcups seemed to shake about and bounce off the ears when on the move.
Simply put, it was my task as Product Development Intern (and as a Design Engineering student) to solve these ergonomic problems. Over the course of the six months, I had to dissect why this was the case and find some solutions. My work would culminate in the suggestion of two potential redesigns.
Starting with User Experience
I begun with user research, to get to the root of the problem. After wearing the P100s for a month, collecting feedback from early-access customers, and analysing online critiques of competitor products, three clear ergonomic problems arose:
🤕 Reducing pressure
Users can’t wear the headphones for more than 30 minutes before needing to adjust the headband position, as it begin to feel like it’s digging in.
📏 Decreasing width
The P100s look quite large to an observer, as the wearer it is difficult to perceive their size when reaching for buttons or moving around.
🏃➡️ Improving stability
There was a suction cupping noise created as the headphones bounced when walking around. They also slide about when shaking one's head.
Headband Comfort
An obvious starting point was to address the headband discomfort. The Cambridge Audio headphones weighed 330g thanks to their premium build, which is a similar weight to the Apple Airpods, Sennheiser HD880s and Meze Audio Empyrean IIs - all headphones which were lauded for their comfort through digging in Reddit audiophile forums and online reviews. Yet, these headphones had noticeably wider headbands.
Headband Comfort
An obvious starting point was to address the headband discomfort. The Cambridge Audio headphones weighed 330g thanks to their premium build, which is a similar weight to the Apple Airpods, Sennheiser HD880s and Meze Audio Empyrean IIs - all headphones which were lauded for their comfort through digging in Reddit audiophile forums and online reviews. Yet, these headphones had noticeably wider headbands.
I collected data on the headband width and weights for competitor headphones available in the office to derive an ideal headband width for the P100s. Though I had limited headphones in the office to test with, there seemed to be a pattern in headphone weight and headband width. The P100s had a headband width comparable to headphones which were 100g lighter.
I collected data on the headband width and weights for competitor headphones available in the office to derive an ideal headband width for the P100s. Though I had limited headphones in the office to test with, there seemed to be a pattern in headphone weight and headband width. The P100s had a headband width comparable to headphones which were 100g lighter.
The plot was missing data points for the strongest competitors, and it did not take into account the relative comfort of the headphones plotted - but the pattern that emerged appeals to common sense. Increasing the area of the headband would naturally decrease the pressure
Transforming this into a design criteria, using concrete, quantifiable numbers to support our goals for improved ergonomics and design, we interpolate an optimal width for the headband (assuming altering the headband is far easier than reducing overall weight)
This data suggests that an 8mm increase in headband width could be the solution to the discomfort growing over longer listening periods wearing the P100s.
Silhouette Width
The Cambridge Audio P100s appeared very wide to anyone looking on. I personally felt a little embarrassed walking around with such massive earcups on.
I discovered the main reason the P100s appeared so wide to an observer was because the distance between the headphone stem and the side of the head was so large. The effect was accentuated when users had long and thin faces or if they had less hair. We defined this horizontal distance between the headphone stem and side of the head as the ‘silhouette’.
Images below illustrate exactly what we mean by this measurement.
Silhouette Width
The Cambridge Audio P100s appeared very wide to anyone looking on. I personally felt a little embarrassed walking around with such massive earcups on.
I discovered the main reason the P100s appeared so wide to an observer was because the distance between the headphone stem and the side of the head was so large. The effect was accentuated when users had long and thin faces or if they had less hair. We defined this horizontal distance between the headphone stem and side of the head as the ‘silhouette’.
Images below illustrate exactly what we mean by this measurement.
Silhouette Width
The Cambridge Audio P100s appeared very wide to anyone looking on. I personally felt a little embarrassed walking around with such massive earcups on.
I discovered the main reason the P100s appeared so wide to an observer was because the distance between the headphone stem and the side of the head was so large. The effect was accentuated when users had long and thin faces or if they had less hair. We defined this horizontal distance between the headphone stem and side of the head as the ‘silhouette’.
Images below illustrate exactly what we mean by this measurement.
I measured this distance for several lifestyle headphones using the dummy head, pictured below. The P100s had a silhouette measuring twice that of competitor models. The design of the earcup, shape and geometry of the yoke, and size of the headband all factored into the silhouette. The following design criteria synthesises this finding into a concrete goal.
The P100 yoke and stem should be shaped or positioned to bring the silhouette closer to 20mm.
Stability
One of the more major insights was finding what factors lead to a stable pair of headphones. I reasoned this to be caused by two factors: clamping force, and the position of the centre of mass for the earcups. I set about validating this with experiments.
A website I stumbled upon, HeadphoneTestLab, detailed its method for estimating how stable the headphone is on the head if its wearer is exercising. Taking the clamping force of the headphones and its weight - one could calculate a ‘Stability Factor’ for the headphones using the following formula.
Stability
One of the more major insights was finding what factors lead to a stable pair of headphones. I reasoned this to be caused by two factors: clamping force, and the position of the centre of mass for the earcups. I set about validating this with experiments.
A website I stumbled upon, HeadphoneTestLab, detailed its method for estimating how stable the headphone is on the head if its wearer is exercising. Taking the clamping force of the headphones and its weight - one could calculate a ‘Stability Factor’ for the headphones using the following formula.
Stability
One of the more major insights was finding what factors lead to a stable pair of headphones. I reasoned this to be caused by two factors: clamping force, and the position of the centre of mass for the earcups. I set about validating this with experiments.
A website I stumbled upon, HeadphoneTestLab, detailed its method for estimating how stable the headphone is on the head if its wearer is exercising. Taking the clamping force of the headphones and its weight - one could calculate a ‘Stability Factor’ for the headphones using the following formula.
This relationship between clamping force and weight made for a rational explanation behind stability - in that increasing the resistance or friction to rotational motion whilst decreasing the total mass in motion would obviously lead to more stable headphones.
This relationship between clamping force and weight made for a rational explanation behind stability - in that increasing the resistance or friction to rotational motion whilst decreasing the total mass in motion would obviously lead to more stable headphones.
This relationship between clamping force and weight made for a rational explanation behind stability - in that increasing the resistance or friction to rotational motion whilst decreasing the total mass in motion would obviously lead to more stable headphones.
There was one small issue - there was no clamping force measurement rig in the office. I decided to build one instead.
Looking online, these cost somewhere around a thousand pounds, and are usually placed in the factory for constant testing. I knew I could create a much smaller, even portable, version to keep in the office, for a fraction of the price, using basic Arduino programming and mechanics. It would not be as precise, but it would work well enough for the sake of the experiment.
I spent two weeks engineering a custom testbed (which involved re-purposing a PCB holder for soldering), incorporating load cells, amplifiers and an Arduino Mega board, to precisely gauge the clamping force of any pair of headphones.
I then took to measuring the clamping force and weight of various ‘lifestyle’ headphones around the office, as well as giving them a rating for how stable they were (through a not-very-scientific process of me walking around, jumping and shaking my head). Applying the earlier clamping force equation gave the following results table:
The results show the most stable headphones had a noticeably higher stability factor, delineating a target zone for clamping force to weight ratio.
Somewhere between 15.44 and 16.18 marks the boundary between the 'very good' and 'best in the game'.
For argument’s sake, let’s say any headphone with stability factor above 16 is considered to be designed well enough for exercise purposes. This lead to the following design criteria.
Keeping the same weight for the P100s (330g) - the clamping force could be 5% higher to make them suitable for exercise, Or, Retaining the same clamping force, the mass could be 5% lighter (weighing closer to 313g)
Centre of Mass
I had some hypothesis that the position of the yoke connection and the centre of mass of the earcup (specifically their distance from the ear) affected the stability of the headphones. This was based on the idea of moments of inertia, similar to how a spinning figure skater controls their speed by extending or pulling in their arms. I thought that by positioning the earcup's centre of mass and yoke connection further from the ear, the headphones would feel more stable.
Centre of Mass
I had some hypothesis that the position of the yoke connection and the centre of mass of the earcup (specifically their distance from the ear) affected the stability of the headphones. This was based on the idea of moments of inertia, similar to how a spinning figure skater controls their speed by extending or pulling in their arms. I thought that by positioning the earcup's centre of mass and yoke connection further from the ear, the headphones would feel more stable.
I devised an experiment using two 3D printed hollow replicas of the P100s. Both models weighed 330g (the same mass as the working P100s), but a steel disc fastened to the inside in alternate locations gave rise to differing centre of mass in each. The two models are pictured below.
In reality, the experiment revealed that this positioning didn’t significantly impact stability. Instead, what it did affect was comfort.
When the centre of mass was further out (the all-green 3D printed headphones), the headband deformed more evenly, distributing pressure more comfortably across the head. In practice, this meant the headphones sat so comfortably that I barely noticed I was wearing them after 30 minutes. This was an incidental but important insight
Industrial Design
With a clear understanding of the mechanical factors governing comfort and the ideal dimensions for the next-generation P100s, I moved on to solely industrial design and prototyping for the final two months.
Of the two final designs, I intended for one to be as close as possible to the P100 factoring in all the latest improvements, and for the other to be free form, meaning it needn’t look anything like the original pair if I wished.
Throughout the earlier months, I had been doing research into all the available headphone styles as well as tinkering with small design changes to the P100s in CAD software, alongside working on all the other mechanical experiments.
In spite of the clear design criteria, I was not satisfied with my first designs and clueless as to what to change. I discovered quickly enough that my understanding of industrial design principles prior to this internship was entirely lacking.
Through conversations with the Head of Design at Cambridge Audio, studying books on sculpting and industrial design, and watching analysis videos of iconic products - I quickly built up my understanding of design principles. These lessons gave me a fresh perspective on form and shape, and introduced me to key ideas of visual hierarchy, empty space and semiotics. I had been made aware of these ideas in my university education, but had had little chance to learn by doing.
I began with sketching - designing for a contemporary aesthetic with distinct features that would be recognisable in a (massively) crowded market. Designs with single armatures or a hidden yoke were growing in popularity at the time - like with the Sony XM5 - as designers pared down headphones to clean, minimal forms.
Hiding the yoke beneath the earcup diverts one’s attention to the other prominent forms of the headphones - the headband and earcups. Therefore, I wanted to create an interesting but minimal form for the earcups, one looking as though shaped from a single block of clay.
With the P100 revamp, the steps were more straightforward. Move the yoke closer towards the ears, then remove some bulk from the earcups.
We whittled down from 8 free-form designs to 1. The stand-out design was this helical earcup aesthetic, with its asymmetric forms. This look was not quite in keeping with the Cambridge Audio design language, but it made for an interesting line of inquiry. The most satisfying redesign to the P100s involved moving the yoke closer to the ears and having it sit flush with the earcup.
I worked solely on these two models for the final week, going back and forth with the Head of Design as I nailed down the details. Adding fillets and radii, removing parting lines, smoothing transitions between joints; these tiny changes are what give life and realism to the rendering, and thus sell the product.
I presented the discoveries from prior experiments and the journey to the final two designs to the engineering department and CEO, marking the conclusion of my internship and the design exploration phase. While the final product direction and design would ultimately be determined by the team after my departure, these two designs and the rationale behind them would serve as a strong foundation for the building to begin.
Design #1
I presented the discoveries from prior experiments and the journey to the final two designs to the engineering department and CEO, marking the conclusion of my internship and the design exploration phase. While the final product direction and design would ultimately be determined by the team after my departure, these two designs and the rationale behind them would serve as a strong foundation for the building to begin.
Design #1
Design #2
Conclusion and Reflection
It was rewarding to be given such independence and trust at Cambridge Audio, and to be able to reinforce so many of the design engineering skills I had learnt in the bachelor’s degree. All my expertise - from user research to mechanical simulations to microcontrollers and circuitry - came in handy at some point. Every tool in my Design Engineering toolkit was put to good use.
When it came to the design phase, I struggled at first. Everything I drew seemed to look awkward and ugly. But I was invested in improving and dove into every resource I could find about product design. Thanks to this education, as well as the invaluable support from Ged Martin (Head of Design), I left feeling more proud and confident in my designs. I felt every design decision I made was intentional, and I grew better at articulating these ideas as I kept iterating. During this time, I found myself thinking about the issue outside of work hours and eager to tackle the problem as soon as I woke up each morning. I still look back on these designs with ideas to make it just a little bit better. It seems design never ends.
Conclusion and Reflection
It was rewarding to be given such independence and trust at Cambridge Audio, and to be able to reinforce so many of the design engineering skills I had learnt in the bachelor’s degree. All my expertise - from user research to mechanical simulations to microcontrollers and circuitry - came in handy at some point. Every tool in my Design Engineering toolkit was put to good use.
When it came to the design phase, I struggled at first. Everything I drew seemed to look awkward and ugly. But I was invested in improving and dove into every resource I could find about product design. Thanks to this education, as well as the invaluable support from Ged Martin (Head of Design), I left feeling more proud and confident in my designs. I felt every design decision I made was intentional, and I grew better at articulating these ideas as I kept iterating. During this time, I found myself thinking about the issue outside of work hours and eager to tackle the problem as soon as I woke up each morning. I still look back on these designs with ideas to make it just a little bit better. It seems design never ends.
Conclusion and Reflection
It was rewarding to be given such independence and trust at Cambridge Audio, and to be able to reinforce so many of the design engineering skills I had learnt in the bachelor’s degree. All my expertise - from user research to mechanical simulations to microcontrollers and circuitry - came in handy at some point. Every tool in my Design Engineering toolkit was put to good use.
When it came to the design phase, I struggled at first. Everything I drew seemed to look awkward and ugly. But I was invested in improving and dove into every resource I could find about product design. Thanks to this education, as well as the invaluable support from Ged Martin (Head of Design), I left feeling more proud and confident in my designs. I felt every design decision I made was intentional, and I grew better at articulating these ideas as I kept iterating. During this time, I found myself thinking about the issue outside of work hours and eager to tackle the problem as soon as I woke up each morning. I still look back on these designs with ideas to make it just a little bit better. It seems design never ends.
"Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read" - Groucho Mark....."Is the problem that we can't see, or is it that the problem is beautiful to me?" - D.C Berman......"You cannot understand good design if you do not understand people; design is made for people." - Dieter Rams......
"Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read" - Groucho Mark....."Is the problem that we can't see, or is it that the problem is beautiful to me?" - D.C Berman......"You cannot understand good design if you do not understand people; design is made for people." - Dieter Rams......
"Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read" - Groucho Mark....."Is the problem that we can't see, or is it that the problem is beautiful to me?" - D.C Berman......"You cannot understand good design if you do not understand people; design is made for people." - Dieter Rams......
"Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read" - Groucho Mark....."Is the problem that we can't see, or is it that the problem is beautiful to me?" - D.C Berman......"You cannot understand good design if you do not understand people; design is made for people." - Dieter Rams......
"Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read" - Groucho Mark....."Is the problem that we can't see, or is it that the problem is beautiful to me?" - D.C Berman......"You cannot understand good design if you do not understand people; design is made for people." - Dieter Rams......
"Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read" - Groucho Mark....."Is the problem that we can't see, or is it that the problem is beautiful to me?" - D.C Berman......"You cannot understand good design if you do not understand people; design is made for people." - Dieter Rams......
"Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read" - Groucho Mark....."Is the problem that we can't see, or is it that the problem is beautiful to me?" - D.C Berman......"You cannot understand good design if you do not understand people; design is made for people." - Dieter Rams......
"Outside of a dog, a book is a man's best friend. Inside of a dog, it's too dark to read" - Groucho Mark....."Is the problem that we can't see, or is it that the problem is beautiful to me?" - D.C Berman......"You cannot understand good design if you do not understand people; design is made for people." - Dieter Rams......
