A Survey on the Affordances of “Hearables” <s> Visibility (Covertness) <s> Wearable computing pursues an interface ideal of a continuously worn, intelligent assistant that augments memory, intellect, creativity, communication, and physical senses and abilities. Many challenges await wearable designers as they balance innovative interfaces, power requirements, network resources, and privacy concerns. This survey describes the possibilities offered by wearable systems and, in doing so, demonstrates attributes unique to this class of computing. <s> BIB001 </s> A Survey on the Affordances of “Hearables” <s> Visibility (Covertness) <s> Electrical hearing aids were the principal site for component miniaturization and compact assembly before World War II. After the war, hearing aid users became the first consumer market for printed circuits, transistors, and integrated circuits. Due to the stigmatization of hearing loss, users generally demanded small or invisible devices. In addition to being early adopters, deaf and hard of hearing people were often the inventors, retailers, and manufacturers of miniaturized electronics. <s> BIB002
The visibility of a wearable device is largely determined by its size and where it is worn. Even though hearables tend to be one of the smaller wearable computing devices, their ear-mounted location tends to make them highly visible in comparison to a smart-watch or pedometer. There is a spectrum of "visibility" for hearables that ranges from completely covert to intentionally visible. Several devices that are essentially invisible, such as Third Skin's Hy  , have been noted as being similar to many recent hearing aid designs BIB002 51] , and it has yet to be determined whether this will be desirable to consumers. The main affordance of covert designs is that they avoid social judgments that can be passed on visibly noticeable wearables  , thereby blending seamlessly into the background of our lives and potentially becoming more likely for user adoption. Another advantage of covert hearables is that they often result in minimal passive noise reduction compared to devices that may block the entire ear canal. However, a downside to completely covert hearables is the confusion that can potentially arise when interacting with the device via voice commands in the presence of others. Hearables that fit completely within the ear, such as Rowkin's Bit or the Bragi Dash, can result in passive noise reduction. To address this, several hearable devices use external microphones to pass sound thru the device, thus allowing the user to adjust the audio mix between outside sounds and device sounds. Such devices, which may be used to augment a user's nearby auditory scene, are quite similar to hearing aids. Several companies, e.g., Resound [53] and Starkey [51] , already market hybrid hearing aids/hearables as "smart hearing aids". Yet another affordance of larger hearables that block the ear canal is the potential to double as water-tight ear-plugs for swimmers, thus offering similar affordances as waterproof smart-watches. In such cases, these hearables often offer stand-alone applications that provide some functionality while the device is not paired to a master device (e.g., mp3 player, computer-generated speech from virtual coaches, etc.). Finally, hearables can also be designed as high-tech fashion pieces, with such devices protruding from the ear in a way that is plainly visible. The technological affordances offered by this design include better options for microphone placement but come with a potential risk for social judgments BIB001 . For example, Apple's AirPods, i.am+'s Buttons, Human's Sound, and several other hearables noticeably protrude or hang from the ear in order to better capture voice interactions. However, it should be noted that as hearables grow in size, so too does their potential to become physically loosened by contact.