Welcome to the fifth post in a series on the Calm Tech Institute’s certification standards! In today’s post, we’ll focus on sound, which is featured in Section 5 of the Calm Tech Certified™ program.
I’m highly sensitive to loud sounds, along with ~17% of the population. It’s amazing how many products make loud sounds in everyday life. Take the hair dryer, for example. These common tools can emit up to 95 decibels when in use, making it about as loud as standard leaf-blowers!
It’s easy to grumble about the sounds of products when you’re using them, but few designers (and companies) have really focused on doing something about it. There’s an enormous amount of opportunity to change how things sound, from hair dryers to lawn mowers. They don’t need to be taken as a given, no matter how disruptive they were to our rest and well-being.
Dyson is the creator of a successful line of hair dryers, but they didn’t make changes to their products until they asked themselves what everyday product categories weren't getting a lot of design love. When they discovered that the hair dryer hadn’t been updated since the mid-20th century, they started to think about what aspects of the hair dryer they could improve. After many interviews, they discovered that sound was an avenue for design (and disruption).
So Dyson figured out a way to make their next hair dryer model extremely quiet. As I explained in my 2018 book, Designing With Sound:
The Dyson Supersonic Hair Dryer, which sells for over $400, was designed with a loudness target from the beginning and consequently is the quietest on the market. The Dyson team went through a four-year, $71 million development process.They cut down component size, improved airflow and component fit, and ultimately reduced the sound by 60%. As reported in Fast Company, “Getting that tight of a tolerance meant that to hold those pieces together at the right distance while they were being assembled, Dyson had to use stabilizing machines ordinarily used to assemble nuclear weapons,” requiring a special license for the machines from the British government.
Sound is often an overlooked factor in product design. But it’s a key principle for products that want to pass Calm Tech certification. Gratuitous, intrusive sounds mar our calm and focus; pleasant audio which soothes or helps tell us important things enhance our lives. Or as we express it as a principle:
Tech can communicate, but it doesn’t need to speak
We often see a lack of this principle in the products around us.
A World of Products Full of Gratuitous Beeps
At a friend’s house for a recent dinner, I couldn’t help but admire their fancy new stove — until I noticed that every time she used it, it made a sharp beep. No knobs. No dials. Just the need to press a flat, black stove with feeble lines showing the space where buttons should be. The beeps beeped whenever she touched any setting.
What’s worse was that the lines denoting these “buttons” were starting to fade from stringent cleaning products, leaving the “fancy” stove more of a scavenger hunt for operations than a cooking companion. Instead of designing the stove to have physical buttons, the product manufacturer made it beep, and because the beep is the only indicator that a “button” (i.e. a capacitive touch sensor) was pressed, the beep wasn’t able to be turned off. The buttons were even harder to locate and press with when her hands were messy from cooking. So much for a relaxing cooking experience! This is the kind of situation where sound didn’t need to be designed at all. The focus could have been on creating an efficient (and quiet) quieter overhead vent fan, not the stove’s ear-piercing beeps themselves.
In the case of the stove, eliminating tactile touch forced a sensory design decision into the auditory space, but less attention was paid to how that sound could work. While the sharp beeps were there to compensate for the oven’s lack of physical buttons, very little attention was paid to how those beeps were designed (See this series’ post on Peripheral Attention for more on why this is such a problem.)
Why are beeps so annoying to begin with, anyway?
Nicer-sounding beeps require more expensive speaker hardware. Microwaves and other appliances can save costs (and space) by choosing tiny speakers, and these speakers are really good at producing high pitched beeps – the kind in the same range that a baby cries – easy to get a person’s attention, but a horrible experience to listen to.
Designing Products With Additive and Subtractive Sound
In product design, sound falls into two categories:
Additive sound: Audio cues added to a product to enhance its utility and enjoyability. The hum that electric vehicles make at slow speeds is a perfect example of additive sound. It’s been required as a safety feature around the world beginning in 2010. But rather than simply make it an audio warning for pedestrians and other drivers, automotive companies work with well-known musicians (BMW and Hans Zimmer, Mercedes and will.i.am) to turn these into amazing aural soundscapes that are core to the car’s brand and driving experience.
Subtractive sound: Unnecessary, unpleasant audio that is removed from a product through various means. Sometimes this is done by making sure components fit comfortably together, so that they don’t emit (too much) noise when the product is in use. In other cases, subtractive elements are part of the product: To reduce the high-pitched whirring sounds of kitchen blenders, for instance, Blendtec created a model which fully containerized the blender itself with a sound-reducing case.
Designing Better Soundscapes for Public Spaces
Audio is especially important to consider when designing public infrastructure, where people will often not be able to see or understand important information.
In Japan, for example, each train station has its own unique melody that informs passengers when their stop is approaching. This is especially helpful to cue sight-impaired or dozing passengers, and when train cars become so crowded, it’s difficult to see outside signs.
Hospital Alerts
The problem of noisy hospital alerts is a huge, largely unsolved one. I wrote about it at length here, highlighting some disturbing data points and offering some solutions to them:
One study of US hospitals showed that nurses take up to 40 minutes to respond to alarms, and another showed caregivers responding to only 10% of alarms. A further study demonstrated that, of all relevant alarms, caregivers could correctly identify only half of them.
Nuisance alerts make up over 90% of pediatric ICU alarms and over 70% of adult ICU alarms. An estimated 80–99% of ECG heart monitor alerts do not require clinical intervention.
Hospitals are already noisy, chaotic environments, and the introduction of alerts can easily overwhelm workers. The Joint Commission on Patient Safety notes:
“The number of alarm signals per patient per day can reach several hundred depending on the unit… translating to thousands of alarm[s] [for each] unit and tens of thousands of alarm[s] throughout the hospital every day.”
I was recently approached by a company that wanted to know more about a Calm Tech approach to hospital sounds. I suggested harmonious sounds with nuances to each, so that medical staff could hear, at a quick listen, what was going on with the patient. I’m hopeful ideas like this will reach the market soon.
Diabetes: The Case for an Unsoothing Alert
Speaking of which, audio alerts related to medical devices should not always be soothing.
A friend of mine has two children with diabetes. He has an ambient display in his kitchen that shows when their blood sugar levels are about to hit critical numbers, and the system uses sound design in a deliberately annoying way.
The product manufacturer understood that common beeps were easy to ignore, and so they designed a random set of annoying sounds to alert everyone in the home about the issue. While it’s not a pleasant thing to hear, it tells the difference between life and death.
Sonifying Data
Some CERN scientists are converting Large Hadron Collider data into sound, using music as a translation tool for particle physics. Since physics data and music share properties like resonances, vibrations, and frequency patterns, this sonification process offers researchers new perspectives and insights on subatomic particles.
Another example is how we can create subtractive sound design for leafblowers.
Subtractive Sound Design for Leaf Blowers
In 2024, four Johns Hopkins University mechanical engineering seniors developed a new solution to one of suburban America's most persistent noise problems. Their improved leaf blower drops the overall noise level by nearly 40% while almost entirely erasing the most obnoxious frequencies.
After months of analysis and over 40 prototype iterations, the team created an innovative attachment that functions similar to a muffler. "Our product takes in a full blow of air and separates it," explained team member Leen Alfaoury. "Some of that air comes out as it is, and part of it comes out shifted. The combination of these two sections of the air makes the blower less noisy."
"It ultimately dampens the sound as it leaves, but it keeps all that force, which is the beauty of it," added student Michael Chacon.
The results are impressive: the design cuts the most shrill frequencies by about 12 decibels—making them 94% quieter—while reducing overall noise by about 2 decibels, creating a 37% perceived reduction in loudness. Team member Madison Morrison describes the difference as going from "a high-pitched whistle" to more of a "wind noise."
The design is patent-pending and Stanley Black & Decker expects to be selling them in two years (you can read more at the Johns Hopkins Website)
Imagine what other breakthroughs in design we can make when we spend more time seeing products with our ears.
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Are you designing a product with sound or moving parts? We'd be happy to help.
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I’ve been so excited by the opportunities for sound in product design that I wrote a whole book on the topic. You can read it here: Designing With Sound: Fundamentals for Products and Services.
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Read the rest of this series: