Acoustics · Systems · Engineering

Janis
Heldmann

Acoustic systems engineer building tools, models, and real-world deployments.

From 64-channel reverberation systems in live venues to bio-based acoustic materials, my work focuses on what happens when controlled models meet messy physical reality.

Janis Heldmann

Case Study · Deployed System

Reverberation Enhancement System
G Livelab Helsinki & Tampere

A deployed multi-channel reverberation system developed through research at Aalto Acoustics Lab and implemented in live music venues across Finland. The project focused on a recurring problem in acoustic engineering: how to move spatial audio research beyond controlled laboratory conditions into systems that remain stable, usable, and reliable during real performances.

64-channel FDN Real-time DSP Spatial acoustics Live deployment
G Livelab Helsinki venue G Livelab Helsinki
Multi-channel speaker array at Aalto Acoustics Lab Multi-channel speaker array · Aalto Acoustics Lab

The Challenge

G Livelab hosts amplified concerts, acoustic performances, and immersive productions in spaces not originally designed around a single acoustic identity.

The difficulty was not simply generating reverberation, but operating a large-scale reinforcement system under live conditions with open microphones, changing stage configurations, strict latency constraints, and engineers whose attention needed to remain on the performance rather than on DSP infrastructure.

The system had to integrate into an existing venue workflow and remain manageable during concerts without requiring specialist knowledge in spatial acoustics or feedback control.

My Role

My work focused on the implementation and deployment of the reverberation system architecture, including real-time DSP integration, feedback mitigation, computational optimisation, and system tuning in the venue environment.

This included translating a research prototype into a stable operational system that could function reliably in everyday concert use while remaining practical for venue engineers to operate.

The System

The reverberation engine is based on a 64-channel Feedback Delay Network using frequency-domain matrix operations to reduce computational cost at high channel counts.

To reduce the risk of acoustic feedback in live conditions, the system employs a time-varying feedback matrix while preserving spatial coherence and perceptual stability.

The architecture was designed around practical deployment constraints: low-latency operation, reliable real-time behaviour, scalable routing, and a control structure that could be used confidently during live events.

From Research to Deployment

Many acoustic systems function well as laboratory prototypes but become difficult to maintain once exposed to the realities of deployment: hardware limitations, unstable feedback behaviour, computational limits, changing room conditions, and operator workflow under pressure.

This project required bridging research in artificial reverberation and spatial acoustics with the practical constraints of live venue operation. The system is now in regular use at G Livelab venues for acoustic and immersive performances, serving as an ongoing demonstration of multi-channel reverberation research in a real-world environment.

40 Loudspeakers · 6 microphones · 64-channel system
2 Deployed venues
🏆 3rd Best Paper · DAFx 2021
JAES Case study currently under review

Published & Submitted Research

  • 2021

    The Role of Modal Excitation in Colorless Reverberation

    Janis Heldmann, Sebastian Schlecht · DAFx 2021, Vienna

    🏆 3rd Best Paper Award · DAFx 2021
  • 2026

    Reverberation Enhancement System Design and Operation: A Case Study

    Gian Marco De Bortoli*, Janis Heldmann*, Karolina Prawda, Sebastian J. Schlecht, Tapio Lokki · Journal of the Audio Engineering Society

    * Equal contribution · Under Review · JAES 2026

Consulting & Tools

Making acoustic complexity usable.

I develop browser-based tools, modelling workflows, and reporting systems that translate acoustic analysis into practical decisions. The focus is not only modelling accuracy, but usability: tools that help acoustic analysis function outside specialist research workflows and support real design, engineering, and material decisions.

The throughline across all of it: reducing the distance between technical knowledge and actionable decisions.

Areas of Work

  • Acoustic modelling and prediction
  • Measurement and characterisation workflows
  • Browser-based technical visualisation tools
  • Research-to-deployment system design
  • Decision-support interfaces for acoustic analysis
  • Scientific reporting and data pipelines

Many acoustic workflows remain fragmented across scripts, spreadsheets, proprietary software, and specialist knowledge that is difficult to communicate outside a research environment. These tools were developed to reduce that fragmentation and create more direct interaction between modelling, measurement, and operational use.

Operational · Material development

JCAL Two-Layer Absorption Calculator

An interactive tool for exploring how porous material parameters influence predicted absorption behaviour across layered structures and orientations.

Originally developed as part of my own research workflow to make the relationships between transport parameters, layer geometry, and acoustic response more directly interpretable during material development. Rather than replacing analytical models, the interface functions as an intuition-building layer on top of them.

Operational
Operational · Resonator design

Dual-Neck Helmholtz Resonator Calculator

A browser-based frequency response tool for resonator acoustics applied to microphone inlet and acoustic cavity design. Built on a lumped-element model with end-correction logic.

Designed to make resonator tuning accessible at the design stage, where iteration between geometry and acoustic behaviour needs to happen before physical prototyping begins.

Operational · v1.4
Research prototype · Inverse modelling

Acoustic Material Identifier

A research prototype exploring whether JCAL transport parameters can be estimated from impulse response measurements using a neural surrogate model.

The forward model phase is complete. The long-term goal is to make material characterisation possible in field and industrial settings where impedance tube measurements are impractical or unavailable.

Research prototype
Production workflow · Research pipeline

Bio-Material Characterisation Pipeline

An end-to-end Python pipeline connecting impedance tube measurement data to JCAL parameter fitting, transfer-matrix prediction, and publication-ready figure generation.

Developed for reproducibility across collaborating research groups and validated against analytical models and measurement workflows. Structured to support the full chain from raw specimen data to modelled acoustic performance.

Production workflow
Custom development · On request

Custom Acoustic Reporting Interfaces

Bespoke browser-based interfaces for acoustic measurement reporting, performance visualisation, and technical communication to non-specialist audiences.

Built for contexts where the primary challenge is not computation but interpretation: making acoustic outputs legible to architects, procurement teams, or clients who need to act on technical data they did not generate themselves.

On request

Case Study · PhD Research

Bio-Based Foam-Formed Sound Absorbers

PhD Research · Acoustic Modelling and Characterisation · Aalto University

JCAL Modelling Impedance Tube Transfer Matrix Method Foam-Forming Ongoing PhD

Bio-based acoustic materials are often treated as too variable and unpredictable for reliable modelling and deployment. My research focuses on how existing acoustic modelling frameworks fail when applied to structurally irregular bio-based materials.

The work centres on foam-formed plant fibre absorbers whose internal density gradients and directional structures challenge assumptions embedded in conventional porous acoustic models. The framework used to evaluate these materials was not built for them.

My work combines acoustic characterisation, JCAL modelling, transfer matrix prediction, and analysis of orientation-dependent behaviour in foam-formed porous structures.

Research Focus

The research combines acoustic characterisation, physical modelling, and material synthesis across collaborations between Aalto Acoustics Lab, Aalto Chemistry Department, and Lumir Oy.

  • JCAL modelling limitations for bio-based fibres
  • Orientation-dependent acoustic behaviour
  • Transfer matrix prediction of layered structures
  • Density-gradient effects in foam-formed materials
  • Linking laboratory characterisation with architectural deployment
Raw Material Reed · Lupine · Softwood
Foam-Forming Creates density gradients that break standard model assumptions
Characterisation Impedance tube · ISO 10534-2 · JCAL fitting
Modelling Transfer matrix method · Analytical fibrous models · Layered approaches
Deployment Lumir Oy · Real-world production and architectural installation
Grand Hansa Helsinki, Lumir bio-based acoustic treatment

Real Deployment · Lumir Oy

Grand Hansa, Helsinki

Lumir's foam-formed bio-based material is sprayed directly onto existing structures in heritage spaces, conforming to complex geometries without altering the visual character of the architecture.

This is the deployment challenge that laboratory characterisation must ultimately serve: a material that performs acoustically, installs without disruption, and remains invisible once in place.

The collaboration between Aalto Acoustics Lab and Lumir Oy creates a direct feedback loop between material synthesis, acoustic characterisation, and real-world installation, shortening the distance between a measurement in an impedance tube and a decision on a building site.

Published Research

  • 2026

    Sound Absorption of Foam-Formed Softwood Fibres: Characterization, Modelling, Prediction

    Janis Heldmann, Jose Cucharero-Moya, Tapio Lokki · Applied Acoustics

    Journal Article
  • 2026

    Orientation-Dependent Acoustic Behaviour of Foam-Formed Reed and Lupine Fibre Absorbers: Limitations of Homogeneous Porous Modelling

    Janis Heldmann, Marike Langhans, Tapio Lokki · Forum Acusticum 2026, Graz

    Conference · Peer Reviewed
  • 2025

    Sound Absorption Prediction of High-Density Foam-Formed Softwood Fibres

    Janis Heldmann, Jose Cucharero-Moya, Tapio Lokki · Forum Acusticum / Euronoise 2025

    Conference
  • 2024

    Characterization, Modelling and Prediction of Bio-based Foam-Formed Fibres for Sound Absorption

    Janis Heldmann, Jose Cucharero-Moya, Tapio Lokki · INTER-NOISE 2024

    Conference
  • 2023

    Modelling of Hierarchical Pore Structures in Freeze-Dried Pectin Cryogels

    Janis Heldmann, Makoto Ueki, Tapio Lokki · Symposium on the Acoustics of Poro-Elastic Materials

    Conference
  • 2023

    Bending of Sound Waves in the Vicinity of Porous Materials

    Arif Yurek, Janis Heldmann, Tapio Lokki · European Acoustics Association Convention

    Conference

Artistic Practice

Performance, sound design,
and lecture-based artistic work.

Over the past decade I have worked across breakdance, contemporary dance, theatre, and interdisciplinary performance in Germany and Finland, including stage performance, sound design, teaching, and artistic collaboration.

Currently developing lecture performances that combine movement, spoken text, live music, and scientific content. The work explores ecological and biological systems through embodied experience rather than representation.

10+ Years international performance
🏆 German Champion · Battle of the Year 2011 & 2012
3 Ongoing lecture performance projects
Lecture Performance · Ongoing

I, Holobiont?

with Nella Turkki · Herne, 2025–2026

A lecture performance exploring the idea of organisms as interconnected living systems composed of host and microbial life. Combining dance, spoken text, live music, and scientific narration, the work examines how ecological and biological interdependence shapes human behaviour and perception.

Performed and touring.

Performance · Sound Design · 2022

Metsänalaiset

Under the Forest · with Nella Turkki · Varkaus / Vantaa

A dance-theatre piece set in a forest environment. Janis performed and created the sound design, building a spatial soundscape drawn from the mycorrhizal networks that connect trees beneath the soil.

Lecture Performance · In Development

Juurimatka

Root Journey

A lecture performance in development combining plant biology, embodiment theory, and personal narrative.

Performance History

Stage career spanning breakdance competition at world level, contemporary dance, and theatre with companies including Goethe Theater Bremen, Schauspielhaus Bochum, Tanzhaus NRW, and Renegade. Teaching and artistic direction at PACT Zollverein, Folkwang Universität, and Grillo Theater Essen.

2025Edged in the Skin · Sound Design · Mia Malveniemi Company · Vaasa
2021ILMA · Sound Design & Live Music · by Nella Turkki · Helsinki
2018V.I.E.R · with Lin Verleger · Pottporus Festival, Herne
2018Basmalla · by Neco Celik · Zeche 1, Bochum
2017The Hidden Door · by Cesar Iglesias Ungo · Tanzhaus NRW
2016Akika X · by Samir Akika · Goethe Theater Bremen
2015Einer Flog über das Kuckucksnest · Goethe Theater Bremen
2015Ruhm · by Neco Celik · Schauspielhaus Bochum / Renegade
2013Ruhr-Ort · by Susanne Linke · Renegade / Schauspielhaus Bochum
2011Zoff in Chioggia · by Nuran David Calis · Schauspielhaus Bochum

Full production history and artistic CV available on request.

Contact

Open to the right opportunity.

Currently completing PhD research at Aalto University with a focus on acoustic modelling, characterisation, and deployable technical systems.

Interested in Application Engineering, applied R&D, and technical product environments where modelling, measurement, and operational usability intersect. Also available for acoustic consulting, technical tooling, and interdisciplinary collaborations.