Advances in audio ICs for wearable applications are rapidly ushering in new capabilities and expanded product offerings. Two areas seeing substantial advances include audio ICs based on the Bluetooth LE Audio Specification, which is the basis of Auracast broadcast audio, as well as MEMS microphone ICs.
Qualcomm’s 2023 annual State of Sound Survey reports on global audio consumer behaviors and desires, and audio IC manufacturers are addressing many of these trends. Survey highlights include the following:
- Earbuds and headphones are increasingly crucial for activities like working, commuting, gaming and exercising.
- The need for true wireless earbuds and headphones is growing, with listeners wearing the devices daily and for long periods.
- 69% of consumers list lossless audio quality as a purchase driver for wireless audio devices, as well as low audio latency, spatial audio and whole home coverage.
- 42% identify battery life as a purchase driver for true wireless earbuds, while 31% name active noise cancellation and 30% report lossless audio quality.
- 75% are interested in Auracast broadcast audio features.
- 38% want their device to also enhance their hearing.
- 61% of respondents indicated that they struggle to hear in busy workplaces, lecture halls and meeting rooms.
In the wearable category, rapidly improving AR/VR headsets, smart bands, earbuds and smart glasses now deliver greater performance with unprecedented accuracy. For example, Bluetooth LE supports a broadcast mode that allows one device to transmit data to an unlimited number of receivers simultaneously. The introduction of Bluetooth LE Audio is the basis of high-efficiency Auracast broadcast audio. Because Auracast is part of Bluetooth, there is no extra technology needed to design it in a product—the only requirement is to support the newest version of Bluetooth LE.
If you were at CES 2024, The Auracast Experience gave attendees a first-hand introduction to Auracast broadcast audio. Auracast targets several applications but is particularly suited for wearables. For example, it enables users to process sound better in noisy environments and transmits sounds to devices like hearing aids, earbuds, smartphones and TVs.
What specifically makes Auracast suited for hearing-challenged users are features like extremely low latency, which avoids echo issues or lip-sync challenges. Although Auracast has the potential to be an assistive-listening system in the future, it is still unknown if Auracast products will be compliant with the Americans with Disabilities Act (ADA) or with existing international standards. Even when Auracast products meet all ADA standards, hearing aids typically have a five- to seven-year lifecycle, making widespread adoption slow.
New audio ICs
The latest audio chips support Bluetooth LE Audio, Auracast Broadcast audio and lossless audio, and they deliver significant improvements in sound quality for small-form-factor earbuds.
At the leading edge is Qualcomm Technologies International Ltd.’s latest audio chipsets. Qualcomm’s S3 Gen 3 Sound Platform and S5 Gen 3 Sound Platform deliver increased processing power and immersive experiences for earbuds, speakers and headsets.
Key features of the S5 Gen 3 platform include a 200-MHz CPU (compared with Gen 2’s 80-MHz CPU), a 350-MHz DSP (versus Gen 2’s 240-MHz DSP) and 1.5× greater memory compared with the previous model. As AI becomes increasingly mainstream, the S5 Gen 3 provides increased AI capabilities. The platform delivers 50× more AI power and 3× more compute than its predecessor.
The S3 Gen 3 platform supports Google Fast Pair, Qualcomm TrueWireless Mirroring and Auracast. The chips improve performance and elevate audio quality with Qualcomm’s aptX lossless 24-bit, 48-kHz music streaming. In addition to support for the Snapdragon Sound with aptX lossless music streaming, it comes with an improved DAC that delivers audiophile quality in mid-tier devices. Other features include AI, hearing enhancement, echo cancellation and noise suppression, and spatial audio, via the Qualcomm Voice and Music Extension Program.
Qualcomm also claims a new tier of ultra-premium performance at low power with its recently announced S7 and S7 Pro Gen 1 Sound Platforms. Targeting ultra-premium wireless earbuds, headphones and speakers, these chips deliver the ability to connect over standard Wi-Fi and Bluetooth. Qualcomm increased the on-board AI capabilities of the chips by 100×, with 6× more overall compute power.
The S7 and S7 Pro chips support Bluetooth 5.4, including compatibility with Bluetooth LE Audio and Auracast. They also deliver premium audio technologies, including Qualcomm’s 4th Generation Active Noise Cancellation, hearing loss compensation and personal sound amplification. The 7 Pro Sound platform is the first to support the company’s Expanded Personal Area Network (XPAN) technology and micro-power Wi-Fi connectivity, extending the audio range across the home, building or campus and supporting up to 192-kHz lossless music quality.
The S7 and S7 Pro Gen 1 are Qualcomm’s advanced audio platforms with low-power compute, on-device AI and advanced connectivity for earbuds, headphones and speakers. (Source: Qualcomm Technologies International Ltd.)
Another low-power audio chip is NXP Semiconductor’s NXH3675, an ultra-low-power Bluetooth LE audio solution with integrated flash. The Bluetooth audio chip enables Auracast and is designed for minimum power consumption in ultra-low-latency applications, such as communication headsets, hearing aids, wireless headphones and earbuds. With an integrated ultra-low-power radio and ultra-low-power DSP, the NXH3675 provides exceptionally long battery life and the opportunity to build miniaturized products.
MEMS microphone ICs
A leading player in the MEMS microphone market, one of Infineon Technologies AG’s latest additions to its XENSIV MEMS microphone product portfolio is the IM69D128S ultra-low-power digital microphone in a small, 3.5 × 2.65 × 0.98-mm package. Targeting hearable applications, such as true wireless earbuds, over-ear headsets and hearing enhancement devices, where battery life is key, the microphone’s signal-to-noise ratio (SNR) of 69 dBA provides crystal-clear audio without a battery-life penalty.
Based on an advanced digital microphone ASIC, the IM69D128S’s current consumption is 520 μA, which is half of the consumption of competitive models on the market with similar performance. It also handles the difficult task of switching between a variety of power and performance profiles without glitches that the user can hear. The pulse-density-modulation microphone incorporates Infineon’s Sealed Dual Membrane MEMS technology to deliver high ingress protection at the microphone level.
The small size of Infineon’s IM69D128S MEMS microphone makes it suitable for true wireless earbuds and over-ear headsets and other space-constrained devices like wearables, smartphones and IoT devices. (Source: Infineon Technologies AG)
It is not just the leading chipmakers that are finding opportunities in audio ICs. Startup Soundskrit, for example, recently introduced the SKR0600 MEMS microphone, a next-generation product with a 67.5-dBA SNR. The directional analog microphones provide pro-audio quality in a 3.50 × 2.65-mm form factor and exhibit a dipole polar pattern from 20 Hz to 20 kHz. The simple addition of an acoustic mesh can convert the SKR0600 into any cardioid-based polar pattern, the company said.
The SKR0600 features a substantial improvement in SNR that allows it to be integrated into smaller form factors than previously possible with directional or beamforming microphone solutions, according to the company. Where MEMS microphones typically require multiple units for directionality, Soundskrit’s SKR0600s and SKR0400s deliver improved directionality and cleaner sound in a single high-SNR microphone.
The SKR0600 microphone is finding interest from a new wave of emerging AR/VR and wearable devices. With built-in directionality, the SKR0600 is suited as a zero-latency beamformer to bring natural hearing-assistive features and real-time translation to its users. The SKR0600 can be used in space-constrained products that need close sound port spacing or devices encountering far-field sound sources. Multiple pairings of these microphones enable realistic spatial recordings, targeting mixed-reality devices.
The Soundskrit SKR0600 directional MEMS microphone with a 67.5-dBA SNR provides pro-audio quality. (Source: Soundskrit)
Advertisement
