Product Design | Audio Electronics | Acoustics | DIY | Audio Innovations
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Bang & Olufsen Unveils Beoplay EQ TWS Earbuds with Adaptive Active Noise Cancellation |
Bang & Olufsen expanded its range of true wireless earbuds with the introduction of Beoplay EQ with adaptive active noise cancellation (ANC). The design is not pitched as any technological breakthrough in ANC, or a "something-killer," but rather as an effective solution for eliminating surrounding noise and enabling total immersion in Bang & Olufsen’s signature sound. The refined design combines the latest specs with precise, powerful sound, and a secure fit. Read More
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Soniox Releases Knowledge Augmented Audio AI for Contextual Transcription |
Soniox already offers a very accurate speech recognition transcription engine for English language. Now the company has released an audio AI solution that automatically annotates the transcribed audio with real-world entities and their contextual information, providing an augmented representation of the audio stream in real-time and low-latency. Soniox offers this novel technology in Soniox APIs, iOS app and web application. Read More
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Nura Offers Personalized Sound and ANC in True Wireless Earbuds |
Nura, the Australian startup that created one of the most effective personalized sound headphone solutions, has been trying to evolve its concept into new form factors. After trying an interesting Bluetooth in-ear design with the Nura Loop, the Melbourne-based company finally launched Nura True, a “TWS with ANC” solution that promises to boost the company's technology and the brand itself. Read More
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Rational Acoustics Announces Major Update with Smaart v8.5 |
Already on the fifth major version update for Smaart v8, Rational Acoustics has now focused its attention on impulse response (IR) mode with an extensive overhaul while providing multiple new feature additions and improvements across the entire program. With the release of Smaart v8.5, a free update, the company also includes a new “Advanced Delay Finder” dialog, new features and improvements to SPL and Transfer Function measurements. Read More
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Ascendo CCRM15 Coaxial Cinema Monitors Available With Beryllium Diaphragms in Passive and Active Versions |
Ascendo Immersive Audio has introduced four versions of its much-anticipated CCRM15 speaker system, now available in passive and powered active models and with Titanium or Beryllium drivers. The 15" point-source axi-symmetric speaker has been designed as a screen channel for large theaters as left, center and right channels or can be used for very large theaters as a surround bed speaker. The CCRM15 Beryllium is now the top performing coaxial model from Ascendo. Read More
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Schiit Audio Introduces Lokius 6-Band Balanced Equalizer |
Schiit Audio continues to expand its range of "gotta have it" audio solutions, this time focusing on reinventing the equalizer...again. The all-new Lokius 6-band balanced equalizer builds on the success of the recent Loki Mini+ (highly recommended for Spotify users), taking things to a new level, now with more bands (6 vs 4), as well as balanced and single-ended input and output. Like the Loki Mini+, the new Schiit Audio Lokius is a single-discrete-gain-stage, LC filtered equalizer. Read More
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LG Updates LG TONE Free TWS Earbuds Lineup with Spatial Processing and Enhanced Performance |
LG Electronics might have given up on the smartphone market, but it’s still determined to sustain market share in the fast-growing true wireless market. The company updated its true wireless stereo offerings with the announcement of the new 2021 LG TONE Free FP series earbuds. Ideal for those who lead active lifestyles, the newest LG TONE Free models feature several enhancements, including advanced Meridian-tuned sound, powerful active noise cancellation, and hygiene-boosting UVnano charging case offered in two of the three models . Read More
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CMA Audio Announces Updated Niimbus US5 and US5 Pro Headphone Amplifiers |
The new Niimbus US5 Pro adds an additional balanced headphone connection. Because the 4.4mm Pentaconn connector has gained popularity as a new balanced headphone connection standard, CMA Audio decided to add this feature and renamed its popular US4+ as the US5 Pro. All other features and specs remain the same. The US5 also adds the 4.4mm Pentaconn connector along with every other feature from the plus model, except for the 256-step relay volume option . Read More
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Guest Editorial
Ofer Shahen-Tov
(Sound Enhancement Algorithms Engineer,
Sound Technologies at CEVA)
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El axer? All eggs er? Alexa!
Conditioning Voice Input for Recognition
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Voice-based control is enjoying healthy growth, at $10.7B in 2020 and expected to reach over $27B by 2026. The advantages are self-evident: hands-free operation and a greatly simplified interface. You state directly what you want without having to navigate menus. But as we’ve all experienced, voice can have its own drawbacks. It works fine in a quiet room when you speak directly at and close to the microphone. But on your phone, through wireless earbuds, in a busy supermarket? Not always so well. AI-based command recognition is important, but even more important is starting with a clear speech signal on which that recognition can operate. Without a clear audio input, your recognizer will often mis-identify commands. Users become frustrated and very quickly stop using the feature. |
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What Makes Voice Difficult
In a related problem, vision recognition, there’s not a lot of ambiguity in routine images, at least in reasonable lighting. However acoustic detection must contend with a lot more interference. Steady background noise – fans, AC, road noise. And other less predictable background noise - music, conversations, dogs barking, car horns, police sirens. Plucking speech from this acoustic jumble is not so simple. But it is very possible, with the right technology.
This filtering offers advantages beyond speech control. It also improves clarity for phone or conference calls. A listener at the other end of the call will hear you and other speakers more clearly over background noise.
Making this possible is an Audio Front-End (AFE), a set of signal processing stages before recognition or communication. This AFE cleans up raw audio signals, emphasizing the most prominent human speaker over other inputs and reducing audio clutter around that signal.
Voice Activity and Direction of Arrival Detection
Many devices hosting voice-based recognition are battery powered - phones, watches and remotes - and must minimize power consumption. Voice activity detection (VAD) is a very low power stage dedicated solely to detecting a human speaker. Everything else can remain powered down until this detection triggers. How are human voices distinguished from a dog barking or other non-human noises? Through some clever yet very deterministic filtering.
Direction of arrival (DOA) detection requires that the device (phone, remote, etc.) host more than one microphone, often several microphones. Direction of arrival can then be deduced (after human filtering is applied) through slight differences in arrival times of an acoustic pulse at each microphone. DOA detection is important to enable the audio front-end to zoom-in (acoustically) on the speaker, as I’ll explain next.
Noise Reduction
There are multiple ways to reduce noise, some spatially sensitive and some based on single-channel filtering. The spatial methods provide a way to zoom in on a speaker through beamforming. This is the same trick wireless technologies use to preferentially select a certain cell tower over others, but here the trick is applied to acoustic rather than radio waves. Here, signal processing uses inputs from multiple microphones to preferentially optimize reception from a certain direction. Which is guided of course by the DOA detection.
Single channel filtering looks more like conventional filtering in the frequency domain. Most trivially this might be a bandpass filter, though more complex options are also possible. The problem with this approach is that it will often compromise trigger word detection and automatic speech recognition. Some cloud platforms ask that such filters be disabled before using their speech recognition services, for precisely this reason. Single-channel filters can still have value in voice communication rather than recognition, to reduce noise for a listener at the other end of the line.
Echo Cancellation
In any enclosed space (a room, a car cabin), sound travels in many directions and can echo from walls, windows and furniture, arriving a little later at microphones than the direct signal. Or a listener may experience unpleasant feedback from their speaker to microphone. Getting rid of these annoyances, which at minimum add to noise, is the job of acoustic echo cancellation (AEC). AEC techniques compare the reference signal, the first received and strongest signal from the direct path to the microphone, to later received echoes. These are similar in form but attenuated, so are readily understood and subtracted from the signal.
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Example for echo cancelation - spectrogram of 2 signals, before and after AEC activation. |
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Putting It All Together
High accuracy voice recognition is only possible with a high-quality audio front end. That demands some pretty sophisticated audio front-end processing, from human voice activity detection through DOA detection, beamforming, echo cancellation and filtering where appropriate. All based on sophisticated signal processing algorithms. Multiple variations are possible depending on your preferred balance between high-end tech and mass market pricing. I’ll explain more next week, and detail how CEVA ClearVox can help you meet both needs. |
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NAD Electronics M33 Masters BluOS Streaming DAC Amplifier - The Complete Package for a Wireless Life
By Stuart Yaniger
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Featured on the cover of audioXpress July 2021 edition, the NAD Electronics M33 Masters BluOS Streaming DAC Amplifier is the subject of review from Stuart Yaniger. In audioXpress August 2020, Stuart Yaniger reviewed the compact but mighty M10 Masters Series Streaming Amplifier from NAD Electronics, which combined performance, an attainable price, and powerful features including a network streamer and the latest Dirac Live room correction with bass control. Shortly after that, he received the new flagship NAD M33 BluOS enabled streaming DAC amplifier, which can serve as the heart of a reference whole-home system. The Masters M33 amplifier design was the first mainstream product to implement the Purifi Audio Eigentakt (self-clocking) amplifier modules, offering a minimum of 200W per channel. In his review, Yaniger carefully examines all the unique features of the M33 before offering the definitive measured overview of this ultra-high-performance amplifier. This article was published in audioXpress, July 2021. Read the Full Article Now Available Here
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An Extended Response, Home Audio 6.5” Midbass Transducer from Purifi Audio
By Vance Dickason
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This new Test Bench article is Vance Dickason's much-anticipated perspective of the Purifi Audio PTT6.5X04-NFA-01 Midbass Transducer, where he highlights some of the new and unique engineering technology achievements, and explores step-by-step everything that makes this product a unique proposition. This 6.5” "Extended Woofer," as Purifi Audio calls it, is an over-achiever, and to help understand why, Dickason talks with Lars Risbo about the research and thought process that lead to many of the features found in this woofer. Including the unique cone assembly that consists of a mildly curvilinear paper cone made with a proprietary fiber mix, a 3.13” concave dust cap, and a V-shaped edge reinforcing ring, and of course the NBR surround, which Dickason calls "probably the most unique surround in the history of Voice Coil’s Test Bench." All the details, exchanges with Lars Risbo, and of course the measurements, are included. This article was published in Voice Coil July 2021. Read the Complete Article Online Here
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