Lenia Margariti, PhD

Voice Assistant Feature

Voice Assistant Feature for the COSMOTE Mobile App
2018-2019

Duration: 2 months

Role: Digital Transformation Analyst / UX Designer, COSMOTE / DT

Team: IT D&I, Software Engineers, Athena Research Center

Methods: Feature Design / Development, UI Design, Creative Coding

Impact: Designed a conversational AI feature for the COSMOTE mobile app, defining data visualization strategy, interaction states, and multimodal feedback patterns that made voice interactions intuitive, understandable, and accessible.

Overview

As part of a collaboration between COSMOTE’s IT D&I Team and Athena Research center, I designed a conversational voice assistant feature for the COSMOTE mobile application.

The feature explored how conversational AI could help customers complete tasks and access information in the existing COSMOTE mobile app through voice interactions, creating a more natural and accessible way to engage with digital services.

The Challenge

Voice interactions introduce unique usability challenges. Unlike graphical interfaces, users need clear feedback about whether the system is listening, processing a request, or responding.

The challenge was to design a voice assistant experience that:

  • Integrated seamlessly within the existing mobile app.
  • Made conversational interactions intuitive and trustworthy.
  • Provided clear feedback throughout the interaction lifecycle.
  • Balanced simplicity with technical feasibility.

My Role

I worked across UX design, interaction design, and front-end implementation.

My responsibilities included:

  • Designing conversational interaction patterns.
  • Defining the voice assistant user experience.
  • Designing the visual language and interface states.
  • Creating prototypes of animated interactions.
  • Developing interface components in React and React Native - including animated waveforms utilizing D3 data visualization library.
  • Collaborating closely with engineers working on speech recognition, NLP, and audio processing.





Above: UI Customization: SVGs for gamification.

Design Process

I mapped the end-to-end voice interaction journey, focusing on key user states:

  • Invoking the assistant.
  • Listening.
  • Processing requests.
  • Delivering responses.
  • Recovering from errors or misunderstandings.

A significant design challenge was communicating these invisible system states through visual feedback.

I initially explored dynamic waveform visualisations that translated audio activity into animated SVG graphics, prototyping with React and D3.js data visualization library.

Through prototyping and technical evaluation, we identified limitations in the available audio data and shifted toward a simpler and more robust interaction model.

The final design used a central voice interaction button combined with animated pulse states that clearly communicated system status and user progress throughout the conversation.



Above: An example of the animated waveform.

Outcome

The project produced a functional voice assistant feature prototype and established interaction patterns for future conversational experiences within the COSMOTE/Deutsche Telecom ecosystem.

The work demonstrated how thoughtful UX design and motion feedback can improve user confidence and understanding in voice-first interactions, while balancing user needs, technical constraints, and implementation complexity.