Voice Enhancement
OnlyVoice™ with In-Ear Accelerometer

Technologies  / Voice Enhancement   / OnlyVoice™ with In-Ear Accelerometer
About
Block Diagram
Audio Examples
Integration
Applications
Additional Information

 

About
 

OnlyVoice™ is Alango’s advanced voice acquisition technology for true wireless (TWS) earphones, Bluetooth headphones and earbuds, and high-performance headsets.

  • adaptive directional beamforming with two external microphones
  • voice processing of internal (in ear) signals acquired via bone conduction microphone (accelerometer).

The combination of these two technologies allows for robust user voice pick-up, even with high noise and/or wind noise in the surrounding environment. Hence, a person or a speech recognition system on the other end can hear and understand the user clearly.

As headset and headphone product designs grow ever more compact, high-quality voice pickup remains a challenge. Holding other things constant, devices with on-ear microphone placement simply cannot match the voice intelligibility performance of a long boom device, where the microphone is placed close to the user’s mouth. In other words, there is a reason why professional-grade headsets have a long boom: voice clarity. Alango OnlyVoice™ is the ideal technological approach to raising voice signal quality on devices without a boom, enabling the same level of speech intelligibility as a long-boom design.

One of the two Alango technologies used in OnlyVoice™ is Adaptive Dual Microphone (ADM) in the end-fire configuration. With two microphones on an axis pointing to the user’s mouth, ADM functions as an optimal directional microphone that attenuates signals arriving from the back and side directions while preserving the front signal.

Alango ADM is a state-of-the-art voice enhancement technology that significantly improves voice-to-noise ratio. By itself, however, it has its limitations. Specifically, beamforming technologies are less efficient when the direction of noise coincides with the direction of the user’s voice. Very high noise levels are also challenging, while exposure to wind is always a problem with external microphones. In these situations, Combining the ADM output signal with the internal microphone signal may provide a voice quality breakthrough.

The second technology implemented in OnlyVoice™ is in-ear voice pickup and processing (via in-ear bone conduction sensor). When a person speaks, the voice signal is propagated not just externally though the air, but also internally, as bone and tissue vibrations through the jaw and ear canal. This internal voice signal can be captured by an in-ear accelerometer (or bone conduction mic).

 

Voice conduction pathways - using OnlyVoice™ with an in-ear accelerometer

 

The resulting signal is relatively isolated from the ambient external noise, and it is completely isolated from wind. As such, it can be efficient for communicating in environments where external microphones become unusable.

Unfortunately, voice pickup by an in-ear accelerometer has its own limitations. First, its bandwidth is limited to approximately 1.5KHz. While it is possible to communicate with such a narrow bandwidth, the user’s voice will sound very muffled and has relatively low intelligibility. Second, in order to pick up the speech signal vibrations, the accelerometer must maintain good physical contact with either the external auditory canal (ear canal) or the bones of the skull/jaw.

Alango’s mixer algorithm overcomes these challenges by combining the output of Adaptive Dual Microphone beamforming with the bone conducted speech signal. The combination is adaptive, based on the respective signal-to-noise ratios of the two outputs as well as the noise spectrum. When the conditions are good and the user is in a quiet environment, external dual microphone beamforming output is chosen. With the addition of ambient noises, the output of the external microphones is mixed with the output of the in-ear accelerometer to achieve the best result. In extremely adverse conditions with high ambient noise, the external microphones cannot be used, and the in-ear accelerometer output alone may be chosen.

In addition to providing the complementary combination of external mic beamforming and in-ear voice processing technologies, OnlyVoice™ incorporates Alango’s echo cancellation, noise suppression, and gains management technologies. This makes OnlyVoice™ a complete solution for enabling unparalleled voice quality in true wireless earphones, Bluetooth headphones, and boomless headsets.

Block Diagram
 

 
Audio Examples
 

Use control buttons on the interactive screenshots to play/stop/navigate

Listen to an unprocessed signal as captured by a single external microphone:

Listen to the output signal processed using Alango OnlyVoice™:

 
Integration
 

Alango OnlyVoice™ can be seamlessly integrated as an option with other Alango technologies into one Voice Communication Package (VCP). VCP includes noise suppression, acoustic echo cancellation, dynamic range compressor, automatic volume and equalization control, speech enhancement, (optional) adaptive dual microphone and several other functions.

 
Applications
 

True wireless (TWS) earbuds and earphones, Bluetooth headphones, High performance communication headsets.

Additional Information
 
OnlyVoice™ With In-Ear (Internal) Microphone
Adaptive Dual Microphone (ADM)
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