Progress: Sound masking for the office.

I’ve been working on a personal project for my portfolio, a sound masking system for the office. Sound masking machines (sometimes wrongfully called white noise machines) emit a low frequency sound that “smothers” the sound of voices. With the machine, as the distance from the speaker increases, the intelligibility of the conversation significantly decreases.

The traditional style of sound masking system used a small fan as the audio source.

Today, the low end to middle range devices use small speakers. The speakers don’t isolate the lower frequency Hz “pink noise” that is most effective at covering human speech. The speakers used today actually are unable to isolate the specific range, producing “white noise”, proven to actually cause discomfort and in some cases, hearing loss. Imagine trying to work with a TV’s static sound in the background. Not fun.

Targeting “pink” noise to match the frequencies of human speech raised the
threshold of audibility just enough to mask intelligibility without
requiring the higher volumes used in [speaker] systems.

  • Herman Miller, “Sound Masking in the Office”, Solutions essay, 2003

Several years back I bought one of those cheap little Homedics alarm clocks that can play different kinds of continuous background noise (you can choose from “white noise,” “rain,” “ocean waves,” etc). It was useless–the sound produced was tinny, not soothing, and did not mask other noises. The Marpac Sleep Mate 980 is far superior to an electronically generated sound that is played from a tinny speaker.

  • Amazon review on the Marpac, one of the few units still available that uses a fan.

I’m only mentioning a couple of blurbs from my research, but I have a good deal of research supporting what form factor/features to pursue. I’m attaching a few of my exploration sketches. I’m exploring three major areas:

    1. Ceiling units (The bulk of the unit would be hidden within the Plenum, the space in the ceiling above the acoustical tiles)
  1. Floor units (sculptural and not meant to be hidden)
  2. A wall mounted unit (this is probably the tertiary direction)

Edit I deleted the images because I revamped them and included them below*

I stuck to an aquatic theme because of the way things sound underwater. Every sound seems to have more bass, more “umph”. Have you ever tried to speak or yell while swimming in a pool? Everything seems very distorted and toned down. Things sound more peaceful underwater.

I’d love to know what you think! I need fresh eyes, for sure. What would you like to see? What do you think is missing?

I’m in the process of developing the design further. Maybe a few more iterations, and some sketch models. I am going to delve into the interface of a remote control as well as testing the acoustics of the shape with a decibel reading app on my phone. I’m going to finish it off with a solidworks model. Ultimately, all tied up with a bow on my website.

Hey Carl,

Cool project idea. Seems like you’ve done quite a bit of technical research on the topic.

It seems like there’s 2 main approaches that I’m seeing:

  1. installed unit that disappears into the wall/floor/ceiling of the building and no one even notices (probably makes the most sense but maybe not that great of a design project)
  2. a personal sound masking device that an individual might purchase for use at home or office (probably more interesting of a project)

Couple questions that come to mind:

  • Who is paying for this? Employer or Employee?
  • Is there a proven productivity increase that might offset the cost of installing these all over the office if that’s the approach you take?
  • Why a manta ray or gaping mouth fish form factor? I get the reference to things sounding different underwater, but does that really translate to a device looking like a fish? I think if you’re going to use the bio-inspiration approach really explore more deeply how mother nature deals with noise. Is there a biological mechanism that muffles sound in nature that could serve as both visual and functional inspiration? How do you take it away from the very literal references to something that will be functional?

I like the technical idea but formally I’m not on board. Either for office or personal desk use I would think the best form is something that disappears visually. I don’t want another wacky designed thing visually cluttering up my space competing with attention with the objects I really care about like hardware, furniture, etc. it can be nicely designed but I think should be unobtrusive. Sorta like a nest thermostat.

Crazy surfaces, vents and whatnot would absolutely make me forget this “functional appliance”. Maybe it’s just me. I believe in “less design the better”.

A black cube on my desk with nice materials, finish and no giant logo- maybe. A swoopy object “not meant to be hidden and displayed”? Nope.

Even better still, how could this thing be more hidden? A stainless cylinder that doubles as a plant pot? A long flat box that has utility to act as a powerbar? If it’s gonna be there, I don’t wanna see it or think about it. Isn’t that the whole point- to make office calming and remove distraction?

Just another POV for what it’s worth.


Ps. Worked on some sharper image and the links “dream machines” or whatever they were called, back in the day…like 15 years ago. They were all styled up and “designy” with 15 sounds to choose from. Waves, white noise, etc. They were “executive” crap. I don’t think that’s what you are going for.


To answer your question on proof, I did find a great deal of supporting evidence, (these are draft panels from my formal presentation of the project)

I cited a report in the first panel that very positive about the device, even with the additional noise, the benefit was proven.

As to the form factor, that is a place that I am certainly stuck. I have three directions that are very feasible. But I am not sure which direction to go with. I have conflicting evidence from different reports. Some say that being able to manipulate the source of the sound helps protect against “habitation”. This is the natural ‘toning out’ the sound that people do. The other report says that hiding the source of the sound is a positive for an unobtrusive product. This really makes the Plenum concept stand out. I’m thinking of a wall mounted unit (that way i can develop a mounting system to make the product semi/portable with multiple mounting locations). This would be better at targeting the lower sized offices. a full blown tile mount would require professional installation.

But that stand alone unit… it can be sexy.

Completely agree with you. I want to go as minimal as possible. So far I have used the zoomorphism and developed the shapes to minimal accents. I will continue to minimize the form. I’m thinking either some hand rendered detail work or physical sketch models. I’m not sure which.

Here are some more of my development sketches,

Again, thank you guys very much for the advice.

Excellent point. I am leaning towards employer, for a board room or some meeting space. But a stand alone definitely becomes available to the employee.

Also, here are some other charts from (2. Hongisto, 2008)

Very compelling stuff. I bought two of the Marpac machines. One for work and one for home.

Thought of you.

Most people I work with in my last three jobs use noise canceling headphones or at least over ear headphones for this. They actively block all the surrounding noise and visually tell people you are focused and working.

If you want to go more minimal, I’d suggest trying a different method for developing the form. In sketch, it’s too easy to make a nice swoopy sketch that looks good, while something simple like a cylinder or rectangle isn’t fun to sketch… So everything gets over designed with lots of surfaces and details.


Interesting problem, but I’m not all that sold on the solution. The research seems to back it and it seems very intuitive that pink noise will make most sounds less distracting. But I’m not sure how well suited it is for an office environment.

I’m not sure how well my experience relates to your scenario but I worked for two years in a highly ventilated lab. The sound was roughly pink noise. It wasn’t terribly noisy. Coming in to the lab, you wouldn’t really notice it. I’ll give you the point that it was very good for concentrating. However, as the whole lab was this noisy environment people would have to talk more loudly which I would find more stressful (voices closer to shouting) and just as distracting. Also, when exiting the building, I would really find it soothing to hear that tone gone, similar but not as extreme to what happens when you shut off a range hood you’ve been under for an hour.

A quick google search on noise in the office space shows up this research from Cornell which basically is saying that everything should be done to lower noise in the workspace including from machinery that produces roughly pink noise like ventilation systems.

For these reasons, I don’t think noise masking would be a good idea for an entire office space. I also agree with yo that noise cancelling headphones seem like a better solution for personal use.

I still think the problem is one that should be addressed. I’d personally look into sound absorption. There might be ways to add sound absorption that haven’t really been tapped into. Both in terms of space management and architectural features but also in the furnishing. One thing I really dig is perforated metal. It looks cool, is fairly cheap and is actually really good at dampening sound on a wide frequency range. Maybe a perforated metal desk, lamp shade, etc. ?

I’d urge you to take a closer look at that article. The mention of air conditioning units and heating units is prefaced by "Distraction is more likely when workers have no control of the noise source and it is unpredictable. To make an assumption, this is probably why AC/heating units are lumped along with telephones, copiers, computers, and printers. All are intermittent sources. The other reports back that up.

Before that it says, “Sound intensities greater that 65 dBA were believed to distract office workers.” That range is where pink noise makes it magic. The masking units emit tones that are actually lower than that dBa level. The lower tones of pink noise have a different effect on the human ear. They are non-invasive, but have a soothing effect.

This is a great report: They took 45 students (fifteen per scenario) and put them in a control room (no noises), an office noise environment, and a masked office environment. The control room, with no noise was best. The masked room was significantly better than the office environment.

Going forward, I’m going to pay close attention to developing a solution that is within the bounds of control, and maybe have a fade-in/fade-out function.

Yo brings up a good point. Instead of an employee buying a personal sound masking device, they could easily get a pair of noise cancelling headphones. All the more reason to make it an employer purchase.

This is a very big side of office noise management. Noise Control in Buildings: A Research Correlation Conference Conducted by ... - National Research Council (U.S.). Building Research Institute - Google Books was a great report on the ways to dampen sound. Basically there are two industry standard ways to control sound.
[*] - Absrption - the ‘shearing’ of sound waves. This requires a large surface area to shred the soundwaves like cheese on a cheese grater. The material needs to be porous enough to allow the sound in, but not as much as to let sound pass right through it.

[*] - Isolation - Deadening the sound. Literally stop the sound by providing a material with enough mass to not allow the waves to go through, i.e. a 12" slab of concrete.

Absorption is definitely something to look into. Ever seen aa Anechoic Chamber?

I’m sorry to have been so dismissive in my first post. My main concern is that if you playback noise at a high enough level to lower the legibility of voice at a standard talking volume, my hunch is that people will just talk more loudly in the office to compensate. This is something Loewen and Suedfeld don’t seem to address, they just added the office noise to the white noise. This is why I see sound masking as a personal solution rather than an office wide solution.

Yes I’m familiar with anechoic chambers. We had a lab assignment in university where we had to look at the transmissibility of sound through various materials. That took place in a small anechoic chamber.

No worries Louis, I’m just obliged to defend my research.

I’m gathering that the project should cover an area of 2-3 workspaces or perhaps a conference room. It will be an employer purchase, for a smaller/midlevel firm. I will have to make a decision on which of the three directions I will go further with.

Quick update:

I’ve been looking at the new c0-working office. These seem to be a great opportunity; having so many people working in close quarters, from different companies, makes privacy a big issue.

From there, the product should be as discrete as possible.