Evolution of my desk part 2: sound-proofing

Part 1 - on keyboards

I work in an open office. Open offices are loud and distracting. I attempted to build a solution.

I started with earplugs and headphones:

I tried building something in this direction:

I ended up with earplugs and sound-cancelling headphones:


The problem

Open offices are loud - for your ears and your eyes. Discussions, pair programming, and phone calls around your desk produce attention-grabbing sound and motion. While each individual distraction may be small and easy to ignore, they collectively leech willpower, focus, and productivity over time.

Headphones alone aren’t enough to drown out people talking. Personally, I’m not willing to constantly play music loud enough to drown out 2+ volume-competing conversations.


Sound context

There’s a lot of material on soundproofing. The material is focused on how to soundproof a room or plug your ears. There is little material on how to sound-proof your head.

Soundproofing options:

Wikipedia article


How to soundproof a room (the size of your head)

Comprehensive article on how to soundproof a room

Reduce unsealed airpaths

Most noise will come through sound’s path of least resistance, then it will bounce around inside the enclosure. That path of least resistance is most likely going to be air - whether it’s a window, gaps around doors, or an open neckline under the box on your head.

Improve mediums of least resistance

Commonly used transparent materials don’t seem to have high noise reduction coefficients [citation needed]. To improve any barrier, you can add multiple layers or make them thicker. The human body has a high noise reduction coeffieicent - this significantly reduces the complexity of sound-proofing your head. Materials with high noise reduction coefficients seem to mostly be very heavy [citation needed] - a major problem for headwear.


Source


Absorb sound inside enclosure

I like to imagine droplets of water bouncing around - it’ll keep bouncing around until it’s completely absorbed by materials on the inside. The main difference being, water is matter and sound is energy.


Source


Cancel sound

Active sound cancelling - wikipedia


Real-life design constraints

  1. Weight: things that are good at blocking sound are also heavy [citation needed]. Heavy things on your head are very uncomfortable.
  2. Air: restricting air movement around your head affects breathing, making enclosures hot and stuffy.
  3. Time to set up: like I learned in my previous desk project, impediments to start doing work (inertia) are highly undesirable.


Thought experiments before building

Thought experiment: container on head

Existing design project: Helmfon


This probably doesn’t block much sound.

This is what you may find if you look around for avante-garde office soundproofing. Generic headphones with horse-blinders would be more effective at achieving the same functional purpose. While it may be useful is signalling, “don’t bother me”, it’s probably useless because:


Sphere on head


Source. Other DIY instructions.

This is probably a good idea.

This could work particularly well if the eyes are closed off with a transparent material and mouth hole is closed off with breathable material. I strongly considered building this, but:


Box on head

Boxes don’t comfortably balance on your head, especially heavy ones. Changing the orientation of boxes to rest diamond-like, point-up distributes the weight on the shoulders and sides of your head. Boxes are convenient to buy and reasonably-priced.


Thought experiment: hanging container

Regardless of which container-on-head option is chosen, it’s likely to be too heavy to support without assistance.





Thought experiment: repurpose existing helmets

Diving helmet

This is probably a decent sound barrier, but very expensive and heavy relative to the sound-blocking it provides.


Source

Motorcycle helmet

This is probably a good idea, although a good one is expensive.

Much of the sound-reduction from motorcycle helmets come from aerodynamics (not generating noise in the first place). Still, they are:

More information


Source


Building a sound-proof head container

I bought an acrylic box on Amazon (£30) and acoustic sealant (~£2) to glue things together while soundproofing the cracks/joints/gaps between the things being glued together.


I bought acoustic barrier (£24), usually used to sound-proof cars.


I cut up the acoustic barrier and washed it.


I glued everything together.






I put it on my head.





It sucked.

I was going to add predator-like dreadlock flaps to seal the neckline and cover the insides in pyramid foam, but it wasn’t working well as it existed already, so I trashed the project:


Source

The more practical solution

My original headphones + earplugs solution was a high starting bar to improve upon. Headphones alone are what most people in open offices default to. Pros:

Cons:


Sound-cancelling headphones

I got these Bose sound-cancelling headphones and they are exceptional. In most open office settings, low-volume music with sound cancelling drowns out all sound. Combined with earplugs, it even drowns out drilling and construction sound.



Earplugs

Even if your ears are perfectly soundproofed, you will be able to hear via bone conduction - bone is used as the medium to transmit sound waves to your eardrums. I’ve found that any type of earplug takes practice to be comfortably wear longer than 20min.

Foam earplugs. These suck. My ear canal is not suited for this type of earplug - foam earplugs and all types of apple earbuds have always fallen out for me. (~$1):


Moulded earplugs These are my favourite. It’s malleable foam plasticy putty-like substance that “hardens” after 30sec. You stuff it as deep into your ear canal as you can in that time window, and 1/2 times you get perfectly-fitted ear plugs. They are very good at blocking sound, but they muffle/distort sound heavily. (~£15 for 2: Source):


Metal earplugs with foam inserts. These were interesting, but not great. For me, they were a slight improvement over foam earplugs (~$30: Source):


Hi-fi earplugs. There are earplugs that reduce the intensity of sound without changing it much. I’ve never tried any before. (~$50: Source):



Conclusion

Wearing earplugs with sound-cancelling headphones are so good at reducing sound that they make loud places tolerable: offices, airplanes, trains… I wear them travelling and it’s the closest to deaf I hope I will ever be.

If those headphones didn’t exist, buying a motorcycle helmet would have been my next choice. Sound-proofing was much more difficult than keyboard layout ergonomics. It required an intuition for materials (density, malleability, price) and the applied physics of sound. What I built wasn’t close to being useful, but I gained some of that intuition in trying.


11 Nov 2018