Step 1
Requirements Analysis
Amsel - Voice Training Mobile App
Impact We Have Created Together
- 10k+ app installs
- 500+ paying users
- 4.8+ App Store rating
When We Joined
We joined at the idea stage and supported the project from educational analysis through development and store release.
Who This Is For
Founders and product teams who want to turn expert knowledge into personalized mobile learning products with algorithm driven content and subscription models.
Duration:
3 months, Partnership ongoing
Type:
End to end product development with responsibility for concept, design, implementation, and launch.
Tech stack:
Product Design
Flutter Apps
Python
Product Design
Flutter Apps
Python
268
Views
Sarah Fuhs
CEO
- Idea
- Solution
- Key components
- Development Process
- Technology & Integration
- Main Features
- Main Challenge
- Advice We Give
- Most Special Step
Idea
Sarah Fuhs is an experienced voice trainer with a background in singing and piano.
After years of teaching and running voice training courses, she wanted to reach more people and make her method accessible beyond in person sessions.
Her idea was to guide users from their first vocal exercises to confident singing through a structured digital experience.
The challenge was to preserve the quality and logic of professional voice training while translating it into a product that works independently and supports individual learning progress.
Solution
We designed and built a focused mobile application that delivers personalized voice training sessions.
The app guides users through onboarding, allows them to configure trainings based on personal needs, and generates suitable sessions automatically.
A server based logic controls exercises, audio files, and rules, enabling continuous improvement without requiring app updates.
A freemium model keeps access simple while supporting sustainable monetization.
Key components
Development Process
Step 2
Concept and Design
Step 3
Implementation
Step 4
Quality Assurance
Step 5
Deployment
We worked closely with Sarah to understand her training method, exercises, and educational goals. All requirements for the first version were documented clearly.
A UI design system aligned with the brand was created. All features were designed iteratively together with Sarah to ensure clarity and focus.
The mobile app was built with Flutter and the backend with Node.js. Close collaboration ensured performance, stability, and clean execution.
Training generation logic was tested extensively. All training combinations were validated together with Sarah.
The app passed store reviews and was released. We continue to maintain and scale the product together.
Technology & Integration
Technology
Product Design
Figma for product redesign and design systems.
Mobile Apps
Flutter for iOS and Android using a single codebase.
Back-End
Python integrated via APIs and extended to support new product features.
Integrations
- Apple App Store In-App Purchases
- Google Play In-App Purchases
Main Features
Training Configuration
Users can configure trainings based on personal goals, difficulty levels, focus areas, and duration.
The configuration process is intentionally simple, allowing users to create meaningful training sessions without technical complexity.
Saved configurations enable repeated use and long term progression while keeping flexibility for changing needs.
Training Generation Logic
The core of the product is the training generation logic.
Based on user settings, the system selects and combines suitable exercises to create balanced training sessions.
This logic runs on an external server, allowing exercises, rules, and audio files to be updated independently from the app.
This ensures flexibility, scalability, and continuous improvement without forcing users to update the app.
Training Execution
Training sessions are executed through a dedicated audio player with a clear navigation layout.
Exercises include audio examples, breathing countdowns, and contextual guidance. Users can pause, repeat, and complete sessions at their own pace.
Finished trainings can be repeated at any time to reinforce learning and consistency.
Training Overview
Users can review completed trainings and see insights such as total training time and number of sessions per month.
A calendar based overview visualizes progress and supports motivation.
This transparency helps users stay engaged and track improvement over time.
Membership Management
The app follows a freemium model. All features are available, but weekly training usage is limited for free users.
Paid memberships unlock unlimited trainings, saved configurations, and personal goals.
Subscriptions are handled via in app purchases with flexible billing options.
Main Challenge
The biggest challenge was structuring voice training sessions dynamically based on individual user settings.
Each exercise serves a specific purpose and must be combined in the correct order and balance.
We documented all parameters, rules, and dependencies in detail to understand how training logic works.
The system needed to remain flexible while producing reliable and meaningful sessions. Moving the logic to a server enabled continuous adjustments without app releases, ensuring long term maintainability and control.
What We Learned
We learned that algorithm driven learning products require deep domain understanding before implementation.
Clear rule definitions and testable logic are essential for reliability.
Why This Matters for Our Partners
These learnings help partners build adaptive learning products that scale without losing quality. They reduce maintenance effort and support long term evolution.
Our Advice
If your product relies on personalized logic, invest early in defining rules and parameters clearly before implementation. This prevents costly rework later.
Most Special Step
The most special part of this project was translating a deeply personal and nuanced craft into a reliable digital system without losing its soul.
Voice training is not a mechanical process. It relies on balance, progression, repetition, and a strong sense of guidance.
Sarah's method is built on years of experience and intuition, which made it especially challenging to formalize into clear rules and logic.
Together, we broke down exercises, intentions, and progressions until they could be expressed as configurable parameters.
Seeing handwritten notes, tables, and training concepts slowly transform into a functioning algorithm was a defining moment.
This step showed how expert knowledge can be scaled responsibly through technology when trust, patience, and deep collaboration are present.
Behance
Sarah Fuhs
CEO
5.0
From the first concept to the final app, the collaboration felt thoughtful and precise. The team translated complex voice training requirements into a clear and intuitive mobile experience. Communication was open, and iterations were handled with care. The result is an app that feels both professional and personal.
Other References
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The references below show how we work, what we deliver, and the outcomes our partners achieve with us.
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