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See SOUND in COLOUR! The CAE SoundCam Because of a neurological disorder called ‘synesthesia’, some people can actually ‘see’ sound or ‘hear’ light (albeit involuntarily). However, most of us would need a device such as this CAE SoundCam, which uses a video camera and a phased microphone array to provide spectral and visual analysis of sounds in real-world scenarios. Its capabilities are fascinating. O ne of the difficulties of reviewing a product like this is that there is nothing that we can compare it to! It’s not like a new scope or spectrum analyser, where we’ve seen dozens of similar devices, and the latest one might offer better performance or some new features. This device can do things that we’ve never seen done before. It’s a genuine first! Like Galileo’s telescope, Marconi’s radio, Edison’s first sound recordings or light bulb, Alexander Graham Bell’s telephone or John Logie Baird’s TV, this instrument is a pioneer. “Everything that can be invented, has been invented” was loudly announced by Charles H. Duell in 1899. He was the Commissioner of US patent office! That just goes to show how right Yogi Berra was when he commented 68 Silicon Chip that “It’s tough to make predictions, especially about the future.” The SoundCam is a product which has been in the making for over 15 years, and has now materialised as CAE’s flagship product. It is a (somewhat) affordable and portable instrument which we think is incredibly innovative, and it’s likely to have numerous applications, many of which haven’t even been thought of yet. You could use it to locate a drone in the dark, find sound leaks in soundproof rooms, spot birds in distant trees at night, identify which part of an engine is starting to fail; the possibilities are many. According to Sales Chief Maik Kuk- “Hands-on” review by Allan Linton-Smith linski, some of the main applications that they see for the SoundCam are in the automotive industry. Not only can it potentially find mechanical problems, but it can also assist with vehicle noise reduction. It can instantly pinpoint annoying squeaks, rattles, engine and wind noise. It has even been used for Formula 1 wind tunnel tests. Not only can it pinpoint sound sources, but it can also quantify the frequency and amplitude and record sessions for downloading. You can watch a short (four-minute) video on the SoundCam at https://youtu.be/-VmPZeYx2II You can also read more technical info and download data from their website at siliconchip.com.au/link/ ab45 Fig.1 shows the SoundCam being Australia’s electronics magazine siliconchip.com.au Fig.1: the first thing we thought of when testing the SoundCam was whether it could be useful to us for loudspeaker development. While we use electronic instruments for analysis as much as possible, we still have to rely on our ears quite often to detect problems such as drivers rubbing on the cabinet, and to assess things like off-axis response. The SoundCam can provide a more objective measurement of these things, and much more. used to examine the high-frequency output from our Senator two-Way Loudspeaker System (September-October 2015; siliconchip.com.au/Series/291) at a 45° angle. The spectrum analysis shows that the tweeter is reproducing sound up to the specified 20kHz maximum frequency at this angle. It also indicates the amplitude distribution is very evenly spread away from the horn. Fig.2 is a closeup of the SoundCam screen during this test, so you can see the results in more detail. Fig.3 shows a grand piano while it is being played. The highest intensity sound (yellow/orange/red) seems to be emanating from the holes opposite the soundboard, not directly from the strings. The SoundCam filters are set to respond from 1.4kHz to 18.4kHz, with the sound mainly being detected up to about 5kHz. The bars represent each chord being played; the lower yellow bars are the bass notes. Fig.4 shows the action side of the instrument, which has 64 MEMS microphones placed in concentric circles, each covered by a Gore-Tex screen for protection from rain, wind and dust. There are four bright LEDs near the centre to assisting with photography and videos. We’ll take a detailed look at MEMS microphones in a forthcoming issue. siliconchip.com.au First impressions The camera arrived in a large foamlined suitcase and is surprisingly sturdy, incorporating the best of German engineering. You could call it “bulletproof”, but it is also beautifully and stylishly designed and is ergonomically correct, which enhances its natural ‘feel’. As soon as you lift it out of its case, it looks and feels really strong. CAE has spent much time with this aspect of its design, which is great for field technicians and others who need to hold its 3.5kg bulk in the air. When used in the field, it might even take some knocks or (shock horror) be dropped. I was convinced that it would survive an explosion, but still handled it with kid gloves because it isn’t mine! We borrowed the review unit from Pulse Acoustic Consultancy who use the SoundCam for various projects, including pinpointing noise problems in squeaky rooftops, air conditioner duct noise and for soundproofing studios. For those who want a fixed setup, an exceptionally sturdy Rollei tripod and carry strap are cleverly included in the case. This has a quick-release attachment, and the whole setup can be assembled in a couple of minutes. We tried tested the unit in as many different applications as possible, but it rained continuously for the whole time it was on loan. We have no doubts that the unit is waterproof as claimed, but were not game to get it soaking wet, especially when the instrument was booked to do some serious work at a local TV studio the next day. So we mainly tested it on loudspeakers Fig.2: while showing the location and intensity of sounds on the image captured by the camera, by default the SoundCam also gives you a ‘waterfall’ type spectrum-over-time display as well as an instantaneous spectrum display to its right. Australia’s electronics magazine October 2020  69 Fig.3 (left): here is a SoundCam view of the strings of a grand piano. Interesting (but perhaps not surprisingly), this shows that much of the sound comes off the sounding board rather than the strings themselves. Fig.4: the array of MEMS microphones that make up the SoundCam, along with the four bright white LEDs surrounding the video camera at the centre of the unit. It is sturdily built. and musical instruments. While they did not make a big deal out of this sort of application, this instrument has excellent potential for speaker and sound equipment manufacturers. It can be used to examine and analyse sound patterns, dispersion factors, directional radiation, buzz and rub and also identify problems such as leaky cabinets and cabinet vibration, rattles and squeaks. Operating principles The SoundCam contains 64 MEMS microphones, each covered by a GoreTex type of material for protection against moisture and dust. The sockets for LAN, recharging and USB are also nicely covered by a rubberised material which can be flipped to one side for use. The four ultra-bright white LEDs come in handy for illuminating objects, for a clear image of the device under test. The instrument identifies the origin of sound sources and pinpoints them by analysing the time of sound arrival at the various microphones on the receiver. The device is totally passive, and unlike a radar which emits signals, the SoundCam is undetectable. That might make it very useful for military and surveillance applications (as well as bird-watching)! The manufacturer advises that there is significantly less resolution at lower frequencies; this particular model has some difficulty pinpointing sounds below about 800Hz. 70 Silicon Chip CAE has larger models to cope with longer sound wavelength (ie, lower frequencies), but this model is their flagship instrument, designed for general field applications. User interface On the operator side of the instrument, there is a large 7-inch 800x480 pixel colour touchscreen. At startup, the screen is split into three sections: a viewing area, a small second screen which shows a vertical spectrum analysis, also with the controls for user-settable filters for upper and lower frequencies. At the lower left, a third screen records frequency over time for the time recording settings selected, or continuous logging. There is also a bargraph calibrated in dB which indicates areas of sound intensity, and this can be adjusted for sensitivity. Adjustments can be made for the distance from sound-generating objects, but this is not a critical setting, and just about any distance setting will typically suffice. You can also switch to a full-screen view, without the spec- Fig.5: the SoundCam can quickly pinpoint sound leaks in places like recording studios. Australia’s electronics magazine siliconchip.com.au Fig.6 the SoundCam mounted on its tripod. Here the four LEDs can be seen brightly glowing. Fig.7 (below): the SoundCam is supplied, with accessories, in a sturdy carry case. trum or filter settings. Still images or videos can be recorded onto an SD card for subsequent analysis and interpretation. Specifications Physical Properties Dimensions Weight Waterproof Anti Theft System Battery Life 340 x 340 x 95mm 3kg IP54 Kensington Lock Min 2.5h Display Size Resolution Touch 155 x 86mm 800 x 400px 10-finger capacitve Embedded Controller Processor Internal Storage Operating System ARM A53 4x1.2GHz with 1GB RAM 32GB Linux for ARM Interfaces USB Ethernet Audio For data export LAN (for running softwae on laptop/PC) 3.5mm for headphones Sensors Microphones Frequency range Sound pressure Sample rate Resolution 64 digital MEMS 10Hz - 24kHz Max 120dB 48kHz 24-bit Optical Camera Type Resolution Lighting Aperture angle Shutter Digital 320x240 (50fps) or 640x480 (16fps) 4 LEDs ±38° Global shutter Power Battery Supply Input Management Li-ion rechargeable (48Wh) Power Adaptor 19V Smart work and charge simultaneously SoundCam applications Finding an annoying noise in a vehicle is always a problem. Often, mechanics have to use a trial and error approach, and some difficult noise problems may never be solved. But with the SoundCam, unwanted sounds can be isolated in a matter of minutes with either an internal “shoot” or an external video of the passing vehicle. Even the weirdest engine noises or external wind-related noises can be isolated and fixed quickly, making it great for body shops as well for mechanics. And note that many parts of an engine or transmission which are worn, damaged or otherwise failing will often make noise, so by pinpointing the source of that noise, it may be possible to determine what needs to be fixed or replaced. Fig.5 shows the SoundCam picking up a sound ‘leak’ entering a soundproofed studio, so that it can be blocked. Annoying noises can also be a real problem in buildings. This includes sound transmissions or leaks between adjacent apartments, offices and factories where soundproofing is insufficient or faulty. Other noise problems can be caused by worn bearings in machinery, badly designed or installed ducting etc. The SoundCam can quickly pinpoint these noise locations. Annoying noises such as rattles, squeaks and buzzes can also emanate from devices such as hair dryers, blowers, washing machines, vacuum cleaners etc. If these problems can be identified during manufacturing, they can be fixed before reaching customers’ hands, improving the user experience and reducing costs associated with returns. This instrument clearly has many other applications not mentioned in the CAE literature. It can spot drones and other “stealth” aircraft (which may be invisible to radar), as well as to detect ground vehicle movement and even people walking in concealed locations such as forests or jungles. It could be used in mining, to detect underground movesiliconchip.com.au ment, locate avalanches and falls, locate vehicles and to assist with the detection of lost or trapped personnel. As you can see from the images earlier, we have also investigated its use in loudspeaker development. Driver buzzing and rubbing are common problems during loudspeaker production, so devices like the SoundCam can simplify quality checks. Loudspeaker cabinets can also be checked for rattles, leaks and unwanted vibration. Conclusion The SoundCam is a highly developed and (relative to its capabilities) affordable instrument which has many applications, and is also easy to use. It is extremely rugged and can easily and quickly set up by just about anyone with minimal instruction. There is no doubt that such an innovative device will find success in many, many different applications. Also, I really want one! This instrument was kindly loaned for review by the Australian distributor, Pulse Acoustic Consultancy, Level 4, 73 Walker Street, North Sydney NSW 2060. For enquiries, contact Mathew Harrison on 0425 467 764 or visit www.pulseacoustics.com.au SC Australia’s electronics magazine October 2020  71