Directional hearing, own voice attenuation, and support for unilateral hearing added to BeHear ACCESS smart hearing amplifier.

About the Alango BeHear line of smart personalized hearing amplifiers

According to the recent World Report on Hearing by the World Health Organization, today more than 333 million people worldwide with disabling hearing loss do not use hearing amplification devices.

The BeHear line of smart hearing amplifiers developed by Alango Technologies (https://alango.com), a leading independent supplier of DSP voice and audio enhancement software technologies for the communication industry, is designed to provide a solution to those people. BeHear products incorporate advanced, Alango-proprietary, fully customizable, self-fitted, hearing enhancement technologies in Bluetooth headsets, thus resolving the problems of stigma, high cost, and long fitting process associated with hearing aids.

BeHear? ACCESS is a hearing amplifier that provides enhanced hearing in specific situations for those with mild-to-moderately-severe hearing loss. It looks (and functions) like a neck loop type Bluetooth? stereo headset but also provides personalized sound enhancement for all-around hearing (face-to-face conversations, live music, nature sounds, mobile/video calls, audio play, TV watching, etc.).

A dedicated smartphone app allows wearers to control the device easily to fit their own unique hearing profile, and later quickly fine-tune sound for any specific situation. BeHear ACCESS integrates telecoil receivers to ensure best possible hearing in facilities equipped with hearing loop technology. Its long-life battery, conveniently recharged in a magnetized cradle, lasts up to 13 hours in personal hearing mode.

The software technologies inside BeHear products are regularly updated, reflecting Alango’s constant quest to improve lives of people with hearing loss. The last update includes 3 important features: 1) improving the user’s communication with others in noisy places (SoundFocus?), 2) increasing the user’s satisfaction (Own Voice Attenuation), and 3) providing a solution to people with unilateral hearing loss (CROS/BiCROS).

SoundFocus? – directional hearing in noise

Why hearing amplification may not be enough.

Understanding spoken language is a complex task involving both the ears and the brain. Ears are responsible for “data acquisition” including the first “preprocessing” stage of acoustic spectral analysis while the brain performs the tasks of sound scene analysis, sound source separation, speech recognition, and speech content extraction. If hearing is normal and the noise is not too loud, the brain receives the full information and can successfully filter out irrelevant sound sources and unwanted noises in most real-life situations. For individuals with hearing loss, however, the task of the brain is much more complicated; if the hearing loss is untreated some important parts of speech, such as fricatives (consonants such as f, s, v, and z), may not reach the brain at all. This forces the brain to rely more on contextual analysis to fill in the informational gap to comprehend the content. With an increase in hearing loss this exercise quickly becomes mentally exhausting, and at some point, practically impossible.

The right amount of frequency-dependent and individually-adjusted hearing amplification makes the subtle speech clues missing due to hearing loss hearable again, thus returning speech comprehension in quiet environments to almost normal levels. However, in noisy situations even the scientifically optimal hearing amplification may not be enough, and even make things worse. The problem is that hearing loss (and its reverse, hearing amplification) is not linear. Weak sounds need to be amplified more to be heard naturally while strong sounds may not require any additional amplification. In technical terms we speak about “sound compression” that reduces the difference between weak and strong sounds. The paradox of even optimal hearing amplification is that it decreases the difference between speech that the brain needs to comprehend and a noise that it needs to ignore. Speech analysis performed by our brain relies on the speech dynamics generated by continuously changing amplitudes of sound in different frequency regions. The time-frequency pattern of these variations is transformed into speech by our brain. A reduction (compression) in the difference between strong and weak sounds (known as “reduced dynamic range”) makes the tasks of speech pattern recognition and separation of speech from noise much more difficult and, at some point, impossible. Consequently, speech understanding in high noise by hearing impaired people requires more than just proper hearing amplification. The brain needs additional help, and the best way to provide such help is by reducing the amount of noise or other unwanted sounds in the acoustic signal before it reaches the brain.

One common way to help the brain perform its sound separation and recognition tasks is to employ directionality, i.e., to identify and amplify mainly sounds coming from the specific direction in which the hearer is looking.

Beamforming - the traditional way of making hearing directional.

In hearing aids, directionality is achieved by acoustic beamforming. The term “acoustic beamforming” comes from its similarity to a beam of light making objects (sound sources) be seen (heard) better in the direction of the light (acoustic) beam, while leaving everything outside that beam in the shadows (attenuated). In traditional hearing aids beamforming is achieved by utilizing two closely spaced microphones in the hearing aid and analyzing the tiny time difference it takes sounds from different directions to reach each of the microphones.

Like a light beam, acoustic beamforming works very well in “free field” conditions (i.e., when the two microphones are not located near other objects). In real life, however, objects such as the human head and shoulders distort the arrival time difference, making acoustic beamforming much less efficient in attenuating “out of beam” sounds. Another problem with beamforming in hearing aids is that when processing for the two ears is not synchronized exactly, beamforming can impair the brain’s ability to localize sound directions. The result may be confusing and impact the brain’s ability to recognize speech, thus making things worse – despite the reduction in noise.

SoundFocus – the new type of directional hearing

Like all living beings experiencing natural directivity with two, relatively far apart, ears, the smart BeHear ACCESS hearing amplifier does not use traditional acoustic beamforming. Instead, BeHear ACCESS directionality is based on an innovative principle that relies on sound field irregularities caused by the reflection and attenuation of sound by the human head and shoulders. We call this technology SoundFocus.

BeHear ACCESS integrates four microphones, one in each earcup and one in each control box (resting on the wearer’s chest). The microphones are positioned in different locations, relatively far apart from each other.

The fact that the body is not transparent to sound is also a factor. For example, sounds coming from the front are well received by the control box microphones, while sounds coming from the rear are attenuated (shadowed) by the body. Sounds coming from left are perceived more strongly through the left earbud microphone, and vice versa. When analyzed together, the four microphones give a very good and quick indication of the direction of the sound in different frequency regions, allowing the technology to decide whether to amplify or attenuate it.

BeHear ACCESS supports three degrees of “sound focus” (directionality): narrow, wide, and omni. Choosing the narrow sound focus will concentrate on sounds coming from the direction corresponding to wearer’s face, or line of sight.

Sounds originating outside the wearer’s field of view will be amplified less, thus improving perceptual sound quality and intelligibility of face-to-face conversations. Choosing the wide sound focus will capture a greater angular range to include sounds from the left and right (relative to wearer’s face). This setting is useful for an outdoor situation, or if a group of individuals is participating in the conversation. The omni sound focus enables a full range of amplified sounds while preserving natural sound localization clues so that wearer will clearly distinguish between sounds coming from the front, sides, and back.

Own Voice Attenuation

The “my voice” echo problem

Hearing their own voice unnaturally amplified has been a major problem for hearing aid wearers for quite some time. The issue is especially pronounced when using earbuds that completely seal off the ear canal. The tighter the seal of the ear bud, the less outside noise is heard and the better the sound quality transmitted through the speaker in low frequencies, but also the greater the annoyance from the perceived echo of the wearer’s own voice, amplified. In the past, clinical treatment of this problem has been fraught with negative consequences, e.g., turning down amplification of low frequencies leading to reduced speech comprehension due to insufficient amplification.

Technology helps

BeHear ACCESS includes the Own Voice Attenuation (OVA) software technology developed by Alango that reduces the perception of the wearer’s own voice echo while amplifying other important voices and sounds. This is achieved by utilizing a unique 4 microphone own voice detection technology specific for the BeHear ACCESS microphone configuration. Due to the different location of the earbuds’ microphones relative to wearer’s mouth, responses to the wearer’s voice are different from those of the control box microphones, which rest on the wearer’s chest.

When the differences between each of the microphones are analyzed for different frequency regions, they create a pattern that is recognized by the algorithm. As soon as the wearer’s voice pattern is detected, the OVA technology quickly reduces the amplification gain for that pattern, making the wearer’s voice amplification less noticeable. The sensitivity of the “own voice” detector as well as the corresponding amplification reduction can be controlled by the user with a single slider in the BeHear ACCESS smartphone app.

Support for Unilateral Hearing (CROS/BiCROS)

Those who rely on one ear for communication often experience difficulties when they need to hear someone located on their “bad side”. The problem can become severe in noisy environments. A typical example is a driver whose healthy ear is located on the side opposite to the passenger. To help these people, BeHear ACCESS smart hearing amplifiers integrate CROS (Contralateral Routing Of Signal) and BiCROS (Bilateral microphones with Contralateral Routing Of Signal) functionality, typically found only in high-end hearing aids.

CROS functionality aids those who have almost no hearing in one ear and close to perfect hearing in the other ear. For such cases CROS technology collects the microphone signal on the bad side and reproduces it in the healthy ear, thus making sounds generated from the bad side much more intelligible by the healthy ear. BiCROS functionality aids those who have no hearing in one ear and some hearing loss in the other ear. BiCROS in BeHear removes unwanted noise from the left and right microphone signals, intelligently mixes the result separately in various frequency regions, amplifies the sounds to address the wearer’s hearing loss, and then reproduces them in the better ear.

CROS or BiCROS functionality will also help people with unilateral hearing enjoy music and other stereo audio content. When activated, all streamed stereo audio will be automatically mixed down to mono and reproduced in the functional ear, thus allowing people to enjoy the full sound spectrum without missing the channel corresponding to the other, damaged side.

More to Come

We will continue to innovate. Next stop – tinnitus masking. BeHear devices will be able to generate masking noises defined by the user, who can easily control the central frequency, the width of the noise shaping filter, and the time modulations.

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