Noise-Cancelling Headphones actively cancel external sounds so the listener can hear their media without distraction. They do this by taking external sound waves from an on-board microphone, inverting the audio signal and mixing that with the media audio. The outside sounds and their inverses cancel each other out before reaching the listener’s ears. There is one downside to these types of noise-cancelling headphones, they are very expensive.
[Mike] works in a wood shop and didn’t want to pony up the hundreds of dollars it would cost for a pair of noise-cancelling headphones, let alone having such an expensive electronic device in a dusty workshop. The solution? Make some headphones that will block out the noise but still allow the comfortable listening of music. This project is simple but effective; inexpensive headphones taken apart and installed in a pair of Industrial Ear Muffs. If you’d like to make your own, [Mike] gives step by step on the above link.
Continue reading “Block Noise, Listen To Music”
Shop-Vacs are great tools, but they do have the notable disadvantage of being loud. Fortunately, much of the noise emanates from the exhaust, and with a muffler or “silencer”, this can be controlled. The results of my noise-recustion experiments were noticeable, reducing the noise by roughly 5.6 decibels. This may not sound like a huge improvement, but since the scale is logarithmic the sound intensity is actually cut by roughly two-thirds, according to this calculator.
As for how to actually make the muffler, I’ve outlined everything in this post. As of now, the Shop-Vac muffler is used in a static configuration, but with some changes it could be used on a mobile vacuum. The disadvantage of this reduction in noise is a slight reduction in suction, but it seems to be an acceptable trade-off in this situation – used for a little CNC router with this adapter.
For a video of the Shop-Vac in action with the CNC router in question, check out the video after the break. Note that this is pre-silencer, so you can definitely hear the vacuum noise! Continue reading “Noise Reduction Techniques for Your Shop-Vac”
[Karl] set out to improve the depth image that the Kinect camera is able to feed into a computer. He’s come up with a pre-processing package which smooths the depth data in real-time.
There are a few problems here, one is that the Kinect has a fairly low resolution, it is also depth limited to a range of about 8 meters from the device (an issue we hadn’t considered when looking at Kinect-based mapping solutions). But the drawbacks of those shortcomings can be mitigated by improving the data that it does collect. [Karl's] approach is twofold: pixel filtering, and averaging of movement.
The pixel filtering works with the depth data to help clarify the outlines of objects. Weighted moving average is used to help reduce the amount of flickering areas rendered from frame to frame. [Karl] included a nice GUI with the code which lets you tweak the filter settings until they’re just right. See a demo of that interface in the clip after the break and let us know what you might use this for by leaving a comment.
Continue reading “Real-time depth smoothing for the Kinect”