Product Design | Audio Electronics | Acoustics | DIY | Audio Innovations
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Bowers & Wilkins Unveils Evolved 800 Series Diamond |
The details about the new Bowers & Wilkins 800 Series Diamond speaker range have been unveiled for some time to global distribution channels and the trade press, and they weren't supposed to become public until September 1. But as always, someone decided to leak the information, and the embargo was lifted today. The new flagship Bowers & Wilkins D4 loudspeaker range introduces an all-new industrial design, updated drivers, and sets even higher standards. Read More
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Panasonic Introduces SoundSlayer SC-GN01 Around-The-Neck Wearable Speaker System |
Every once in a while, the distant memory of the Sennheiser Surrounder Pro (1997) returns, whenever a new company decides to revive the around-the-neck collar speaker concept. This time, Panasonic unveiled its SC-GN01 Wearable Immersive Gaming Speaker System (WIGSS) targeting gamers and marketed as a wearable speaker system that offers "immersive play without sacrificing comfort." The new SoundSlayer SC-GN01 design isn't even wireless unlike most recent solutions in this form-factor. Read More
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Sound Particles Space Controller Makes Immersive Audio Intuitive |
Sound Particles, the innovative 3D audio software company adopted by game production companies and all major Hollywood studios, just released a simple and intuitive solution for spatial audio control. Space Controller is an affordable plug-in and mobile app that together allow users to pan sounds by simply pointing their phone in the direction they want the sound to be. A universal controller for any production format. Read More
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Dan Clark Audio Announces New Stealth Closed-Back Planar Headphones |
High-end headphones can be a very rewarding category for a few very focused manufacturers, and it's always refreshing to see a completely new closed back design that actually involves a serious R&D effort and advances headphone technology further. The new Stealth planar magnetic headphones by Dan Clark Audio (US $3999) are based on a custom-designed planar driver, matched with superior materials and ergonomics. Read More
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Monoprice Unveils New Monolith THX Ultra-Certified Powered Subwoofers |
Monolith, the premium audio brand from Monoprice, launched a new 13” powered subwoofer to its growing line of affordable, THX Ultra-certified home theater solutions. The new subwoofer design, which will be complemented with a 16” version later in the year, was engineered for spaces greater than 3,000 cubic feet in volume. Both use new custom-designed drivers, coupled with a DSP-controlled and 2000W (RMS) power amplifiers, optimized for low distortion bass output in home theater systems. Read More
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L-Acoustics Unveils Ultra-Compact SB10i Subwoofer for High-End Residential and Commercial Projects |
French professional audio manufacturer L-Acoustics is determined to expand its range of solutions to reach also commercial installation and high-end residential markets. The latest product now unveiled by the company meets those requirements in the low-end. The L-Acoustics SB10i subwoofer extends the company's line of SB subs, with a vastly scaled-down enclosure design, not much larger than two side-by-side shoe boxes. Read More
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Fluid Audio Announces Focus Headphones with Frequency Response Correction and Room Simulation Software |
California studio monitor company Fluid Audio has ventured into headphones for recording and mixing and announced the release of its new Fluid Audio Focus headphone playback and mixing system. Following the recent market trend of combining headphones with correction and processing software, Fluid joined forces with Russian software house dSONIQ, and bundled its new Focus headphones with Realphones headphone correction and binaural room simulation solution . Read More
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Noveto Completes Chipset Development to Drive SmartBeaming Technology |
Noveto, the company responsible for the development of one of the most promising audio technologies, with large implications in multiple markets, including mobile and automotive industries, confirmed the successful completion of its proprietary new C1 chipset. The development is designed to drive its SmartBeaming technology, a speaker that dynamically tracks and beams audio to the user's ears, creating a personal audio zone . Read More
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Guest Editorial
Ofer Shahen-Tov
(Sound Enhancement Algorithms Engineer,
Sound Technologies at CEVA)
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Alexa? Pull Clear Speech from Noise
Conditioning Voice Input for Recognition 2
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In my previous blog ( read it here), I talked about methods to pick out a clear voice signal from background noise. This is an essential requirement for reliable voice-based control, even for high quality communication from noisy environments. Paradoxically clear voice pickup is easy to solve if you can throw lots of technology at the problem. Just use high-end voice activity detection, many-microphone beamforming and echo cancellation and you’ll have a premium product for high-end markets. A more interesting challenge is to be able to offer almost as good voice pickup quality at more attractive pricing for your mid-range markets. I’ll talk about techniques for both markets here |
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Voice activity detection (VAD)
This step is the start of the voice pickup pipeline – is someone speaking or not, amid the acoustic background? The first step is simply to look at signal, separating out frames with clear activity from background.
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Figure 1: VAD functionality on an example signal |
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Looking only at the raw detector signal, some detections will be real and some will be false. Setting a good threshold for SnR can help find a good tradeoff. In a value-priced product a purely energy-based detection (integration in the window) may be enough. A premium product may add adaptive detection using a neural net. Both profiles are common in wearables and earbuds. The common analysis to compare these techniques is to plot true positives versus false positives on a receiver operating characteristics (RoC) curve. This tradeoff between false positive and true positive detections will help you decide how to tune your product. |
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Figure 2: RoC chart of several VAD solutions |
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Direction of arrival (DOA) detection
This algorithm compares slight delays in arrival time for a detected signal at different microphones. Naturally, pickup for each microphone should be selective to human voice profiles. Then, accuracy of detection will be a function of the number of microphones used and the distribution of those microphones.
High-end devices like smart speakers or smart TVs can generally assume that the speaker is at some distance away, so DOA will be quite accurate. Mid-market products will often be much closer to the speaker and will almost certainly use less microphones, so DOA must be adjusted accordingly. This factor should be considered especially for beamforming, important for noise reduction in the next section.
Noise reduction
Arguably the best possible noise reduction is spatial – zooming into the speaker using beamforming techniques. Which again requires multiple microphones and uses the DOA as a starting point to select where it should zoom in. The more microphones you can use, the more accurately you can zoom in on the speaker, effectively suppressing all other sources of noise. But even with two microphones you can create an improved level of discrimination over one microphone.
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Figure 3: Beamformer filter pattern using 3 mics and 7 mics |
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For a single microphone, beamforming isn’t possible. This might not be a problem if the speaker is naturally close to the mic. For example, voice pickup in earbuds through bone conduction may already be sufficiently noise free. Also remember that for speech recognition, cloud providers recommend against using filters to remove noise since these can also reduce recognition accuracy.
Echo cancellation
Echoes, mostly from fixed surfaces around a room, create a tail of background noise related to the speaker signal. On low-end devices, the loudspeakers and the plastic capsule of the device tend to add noise or even non-linear effects. Which means that AEC algorithm must be tunable not only to environmental echoes but also to any possible acoustic noise from the device housing.
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Figure 4: The standard pipeline for AEC usage |
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Figure 5: Echo tail amplitude ration over time in 3 different rooms |
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CEVA ClearVox across the range
As you can see, one size does not fit all when it comes to accurate voice pickup. Solutions must be crafted to meet the needs of different markets, premium versus mass-market objectives. CEVA can help you satisfy both targets, to get maximum value from a high-end implementation with NN-assisted algorithms and many microphones for audio zoom. Or a value-based implementation with energy-based VAD and only two or even one microphone. CEVA has many years of experience in this field. In audio applications for earbuds, headsets, and spatial audio. All this experience is encapsulated in our CEVA ClearVox product, available for CEVA DSP and Arm platforms. |
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Build a Single-Ended Guitar Tube Amplifier
By Costas Sarris
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In this project article for audioXpress, the author shares his guitar tube amplifier, a simple, low-wattage project that any DIYer can easily build. Costas Sarris believes in building simple tube amplifier designs, with simple circuits that he found to work better, particularly when the electric signals carry music information, because the signal distortion is easily handled. Inspired by late 1950s Fender “Princeton” and “Champ” amplifier designs, this is an extremely musical design that is certain to deliver very rewarding results and work well in the studio or a stage. "When a guitarist friend urged me to build a guitar tube amplifier, we agreed that the amplifier design should be a simple, low-wattage single-ended amplifier — built much like a Swiss army knife — for everyday use. The essence of this amplifier is simplicity. That’s what makes it different," he shares. This article was originally published in audioXpress, June 2015. Read the Full Article Now Available Here
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Voice Coil Acoustic Patents |
Desktop Audio Monitor System and Method
By James Croft
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In this Acoustic Patents review article, James Croft (Croft Acoustical) looks at one of the most interesting concepts for a “Desktop Audio Monitor System and Method,” US Patent 9036837, granted in 2015 to James Tuomy (Framingham, MA), Barry Michael Kosherick (Hudson, MA), Laurie Wilk (Framingham, MA), and J. Richard Aylward (Ashland, MA). The concept was actually introduced to the market a year earlier, and made its big debut at the NAMM Show 2015, with the company Phasx Technologies. The patent, filed in 2010 was deservedly granted to this desktop audio loudspeaker system with an innovative radiating solution to reduce multipath effects caused by reflection of sound by the desktop. This article was originally published in Voice Coil, August 2015. Read the Full Article Now Available Here
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