Voice assistants (VAs) are present in homes, smartphones, and cars. They allow users to perform tasks without graphical or tactile user interfaces, as they are designed for natural language interaction. However, we found that currently, VAs are emulating human behavior by responding in complete sentences, limiting the design options, and preventing VAs from meeting their full potential as a utilitarian tool. We implemented a VA that handles requests in three response styles: two differing short keyword-based response styles and a full-sentence baseline. In a user study, 72 participants interacted with our VA by issuing eight requests. Results show that the short responses were perceived similarly useful and likable while being perceived as more efficient, especially for commands, and sometimes better to comprehend than the baseline. To achieve widespread adoption, we argue that VAs should be customizable and adapt to users instead of always responding in full sentences.

Many people utilize audio equipment to escape from noises around them, leading to the desired isolation but also dangerously reduced awareness. Mediation of sounds through smarter headphones (e.g., hearables) could address this by providing non-uniform interaction with sounds while retaining a comfortable, yet informative soundscape. In a week-long event sampling study (n = 12), we found that users mostly desire muting or a distinct "quiet-but-audible" volume for sound sources. A follow-up study (n = 12) compared a reduced interaction granularity with a continuous one in VR. Usability and workload did not differ significantly for the two granularities but a set of four states can be considered sufficient for most scenarios, namely: ''muted'', ''quieter'', ''louder'' and ''unchanged'', allowing for smoother interaction flows. We provide implications for the design of interactive auditory mediated reality systems enabling users to be safe, comfortable and less isolated from their surroundings, while re-gaining agency over their sense of hearing.

Media (e.g. videos, images, and text) shared on social platforms such as Facebook and WeChat are often visually enriched through digital content (e.g. emojis, stickers, animal faces) increasing joy, personalization, and expressiveness. While voice messages (VMs) are experiencing a high frequent usage, they currently lack any form of digital augmentation. This work is the first to present and explore the concept of augmented VMs. Inspired by visual augmentations we designed and implemented an editor, allowing users to enhance VMs with background sounds, voice changers, and sound stickers. In a first evaluation (N = 15) we found that participants used augmentations frequently (2.73 per message on average) and rated augmented VMs to be expressive, personal and more fun than ordinary VMs. In a consecutive step, we analyzed the 45 augmented VMs recorded during the study and identified three distinct message types (decoration, composition and integrated) that inform about potential usage.

Adoption and use of smartphone-based asynchronous voice messaging has increased substantially in recent years. However, this communication channel has a strong tendency to polarize. To provide an understanding of this modality, we started by conducting an online survey (n=1,003) exploring who is using voice messages, their motives, and utilization. In a consecutive field study (n=6), we analyzed voice messaging behavior of six avid voice message users in a two-week field study, followed by semi-structured interviews further exploring themes uncovered in our survey. Conducting a thematic analysis, we identified four themes driving voice messaging usage: convenience, para-linguistic features, situational constraints and the receiver. Voice messaging helps to overcome issues of mobile communication, through ease of use, asynchronous implementation, and voices’ rich emotional context. It also was perceived as enabling more efficient communication, helps to handle secondary occupations, and better facilitates maintenance of close relationships. Despite the increased effort required to listen to a voice message, they complement communication with people we care about.

Natural haptic feedback in virtual reality (VR) is complex andchallenging, due to the intricacy of necessary stimuli and re-spective hardware. Pseudo-haptic feedback aims at providinghaptic feedback without providing actual haptic stimuli butby using other sensory channels (e.g. visual cues) for feed-back. We combine such an approach with the additional inputmodality of muscle activity that is mapped to a virtual force toinfluence the interaction flow.

Continuous advances in personal audio technology (e.g. headphones), led to efficient noise cancellation and allowed users to build and influence their personal acoustic environment. Despite the high adoption and ubiquitous character of the technology, we do not fully understand which particular factors influence and form usage patterns. As a step towards understanding the usage of personal audio technology, we conducted two focus groups (n=10) to investigate current headphone usage and users' wishes regarding current and future personal audio technology. Based on this data, we derive a model for what we call personal soundscape curation. This model was assessed with the data of a crowdsourced survey on Amazon Mechanical Turk (n=194) on state of the art practices. Personal soundscape curation allows to describe usage strategies (curation, adaptation, renunciation) and break down influencing factors of context and environment as well as illustrate which consequences may arise from the users' behavior.

We present SwiVRChair, a motorized swivel chair to nudge users' orientation in 360 degree storytelling scenarios. Since rotating a scene in virtual reality (VR) leads to simulator sickness, storytellers currently have no way of controlling users' attention. SwiVRChair allows creators of 360 degree VR movie content to be able to rotate or block users' movement to either show certain content or prevent users from seeing something. To enable this functionality, we modified a regular swivel chair using a 24V DC motor and an electromagnetic clutch. We developed two demo scenarios using both mechanisms (rotate and block) for the Samsung GearVR and conducted a user study (n=16) evaluating the presence, enjoyment and simulator sickness for participants using SwiVRChair compared to self control (Foot Control). Users rated the experience using SwiVRChair to be significantly more immersive and enjoyable whilst having a decrease in simulator sickness.

We present FaceTouch, a novel interaction concept for mobile Virtual Reality (VR) head-mounted displays (HMDs) that leverages the backside as a touch-sensitive surface. With FaceTouch, the user can point at and select virtual content inside their field-of-view by touching the corresponding location at the backside of the HMD utilizing their sense of proprioception. This allows for rich interaction (e.g. gestures) in mobile and nomadic scenarios without having to carry additional accessories (e.g. a gamepad). We built a prototype of FaceTouch and conducted two user studies. In the first study we measured the precision of FaceTouch in a display-fixed target selection task using three different selection techniques showing a low error rate of 2% indicate the viability for everyday usage. To asses the impact of different mounting positions on the user performance we conducted a second study. We compared three mounting positions of the touchpad (face, hand and side) showing that mounting the touchpad at the back of the HMD resulted in a significantly lower error rate, lower selection time and higher usability. Finally, we present interaction techniques and three example applications that explore the FaceTouch design space.

This paper presents Glass Unlock, a novel concept using smart glasses for smartphone unlocking, which is theoretically secure against smudge attacks, shoulder-surfing, and camera attacks. By introducing an additional temporary secret like the layout of digits that is only shown on the private near-eye display, attackers cannot make sense of the observed input on the almost empty phone screen. We report a user study with three alternative input methods and compare them to current state-of-the-art systems. Our findings show that Glass Unlock only moderately increases authentication times and that users favor the input method yielding the slowest input times as it avoids focus switches between displays.