Smart Hearing

As we have already seen, there are several enabling technologies that need to be in place in order to put together an effective mediated reality system. In a visual augmented reality system, this includes having some sort of device for recording the visual scene, tracking objects within it, rendering augmented features in the scene and the some means of displaying the scene to the user. We reviewed a range of approaches for rendering augmented visual scenes in the post Taxonomies for Describing Mixed and Alternate Reality Systems, but how might we go about implementing an audio based mediated reality?

In Noise Cancellation – An Example of Mediated Audio Reality?, we saw how headphone based systems could be used to present a processed audio signal to a subject directly – a proximal form of mediation such as a head mounted display – or a speaker could be used to provide a more environmental form of mediation rather more akin to a projection based system in the visual sense.

Whilst enabling technologies for video based proximal AR systems are still at the clunky prototype stage, at best, discreet solutions for realtime, daily use, audio based mediation already exist, complemented in recent years by advanced digital signal processing techniques, in the form of hearing aids.

The following promotional video shows how far hearing aids have developed in recent years, moving from simple amplifiers to complex devices combing digital signal processing of the audio environment with integration with other audio generating devices, such as phones, radios and televisions.

To manage the range of features offered by such devices, they are complemented by full featured remote control apps that allow the user to control what they hear, as well as how they hear it – audio hyper-reality:

The following video review of the here “Active Listening” earbuds further demonstrates how “audio wearables” can provide a range of audio effects – and capabilities – that can augment the hearing of a wearer who does not necessarily suffer from hearing loss or some other form of hearing impairment. (If you’d rather read a review of the same device, the Vice Motherboard blog has one – These Earbuds Are Like Instagram Filters for Live Music.)

SAQ: What practical challenges face designers of in-ear, wirelessly connected audio devices?
Answer: I can think of two immediately: how is the wireless signal received (what sort of antenna is required?) and how is the device powered?

Customised frequency response profiles are also supported in some mobile phones. For example, top-end Samsung Android phones include a feature known as  Adapt Sound that allows a user to calibrate their phone’s headphone’s based on a frequency based hearing test (video example).

Hearing aids are typically comprised of several elements: an earpiece that transmits sound into the ear; a microphone that receives the sound; and amplifier that amplifies the sound; and a battery pack that powers the device. Digital hearing aids may also include remote control circuitry to allow the hearing aid to be controlled remotely; circuitry to support digital signal processing of the received sound; and even a wireless receiver capable of receiving and then replaying sound files or streams from a mobile phone or computer.

Digital hearing aids can be configured to tune the frequency response of the device to suit the needs of each individual user as the following video demonstrates.

Hearing aids come in a range of form factors – NHS Direct describes the following:

  • Behind-the-ear (BTE): rests behind the ear and sends sound into the ear through either an earmould or a small, soft tip (called an open fitting)
  • In-the-ear (ITE): sits in the ear canal and the shell of the ear
  • In-the-canal (ITC): working parts in the earmould, so the whole hearing aid fits inside the ear canal
  • Completely-in-the-canal (CIC): fits further into your ear canal than an ITC aid

Age UK further identify two forms of spectacle hearing aid systemsbone conduction devices and air conduction devices – that are suited to different forms of hearing loss:

With a conductive hearing loss there is some physical obstruction to conducting the sound through the outer ear, eardrum or middle ear (such as a wax blockage, or perforated eardrum). This can mean that the inner ear or nerve centre on that ear is in good shape, and by sending sound straight through the bone behind a patient’s ear the hearing loss can effectively be bypassed. Bone Conduction or “BC” spectacle hearing aids are ideal for this because a transducer is mounted in the arm of the glasses behind the ear that will transmit the sound through the bone to the inner ear instead of along the ear canal.

Sensorineural hearing loss occurs when the anatomical site responsible for the deficiency is the inner ear or further along the auditory pathway (such as age related loss or noise induced hearing loss). Delivering the sound via a route other than the ear canal will not help in these cases, so Air Conduction “AC” spectacle hearing aids are utilised with a traditional form of hearing aid discreetly mounted in the arm of the glasses and either an earmould or receiver with a soft dome in the ear canal.

The following video shows how the frames of digital hearing glasses can be used to package the components required to implement to hearing aid.

And the following promotional video shows in a little more detail how the glasses are put together – and how they are used in everyday life (with a full range of digital features included!).

EXERCISE: Read the following article from The Atlantic – “What My Hearing Aid Taught Me About the Future of Wearables”. What does the author think wearable devices need to offer to make the user want to wear them? How does the author’s experience of wearing a hearing aid colour his view of how wearable devices might develop in the near future?

Many people wear spectacles and/or hearing aids as part of their everyday life, “boosting” the perception of reality around them in particular ways in order to compensate for less than perfect eyesight or vision. Advances in hearing aids suggest that many hearing aid users may already be benefiting from reality augmentations that people without hearing difficulties may also value. And whilst wearing spectacles to correct for poor vision is a commonplace, it is possible to wear eyewear without a corrective function as a fashion item or accessory. Devices such as hearing spectacles already provide a means of combining battery powered, wifi connected audio as well as “passive” visual enhancements (corrective lenses). So might we start to see those sorts of device evolving as augmented reality headwear?

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