Hi Andrew

Very interesting video. This gives a base line for these machines when typing on a hard surface. I would like to see this experiment repeated with a vibration absorbing pad under each machine as it's tested. Judging by the keyboard layout, I'd say you're probably in Western Europe. Go to your local sports and fitness store and buy a cheap yoga mat. Cut a 35cm square from the mat and place it under each typewriter in turn as you repeat the test. It will be interesting to see just how much the sound level is reduced when using a mat. All the best,

Sky

You can't really compare sound levels without measuring and factoring in the hardness of each machine's platen. If you were to compare two identical typewriters, one with a rock-hard platen and the other with a platen that has fresh rubber, you would immediately hear the difference the platen makes to a machine's sound.

I'd also argue that the overall condition of each typewriter has to be a part of the discussion. There are a number of components that contribute to the amount of noise a typewriter makes, and if some are worn or missing the test really isn't indicative of that particular make and model.

Sound levels are tough comparisons to make, one that would have been easier and more conclusive when all of the machines were brand new in from-the-factory condition. In your comparison, it can only be claimed that your particular Underwood 310 is less noisy than your other typewriters. Another collector could compare the same group of machines and find it's a different model that is the quietest of the bunch.

I recall others here mentioning those backing sheets made of a plastic-like film, and experimenting with similar materials that are available today. As you can imagine, the platen hardness subject is one that is often revisited here. I've had good success using rubber rejuvenator spray, and of course I always use a paper backing sheet - or two - both of which help to reduce the sound level of a machine.