
Will J. Cassidy
- PhD with L-Acoustics
- Co-Founder of Ember DSP
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wjcassidy
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637 contributions in the last year
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Publications
Deep Learning and Differentiable Optimisation
Closed-Loop Differentiable Optimisation for Active Acoustics
2026 - The 19th International Workshop on Acoustic Signal Enhancement
Cassidy, W. J., Coleman, P., Mason, R., Venkatesh, S., Lladó, P. and De Sena, E.

Summary
This study proposes a closed-loop optimisation pipeline for active acoustic enhancement systems that accounts for sound propagation into, within, and out of the system—rather than optimising only the open-loop transfer paths. This method enables a multitude of optimisation tasks including matching a target room's late reverberation.
Perceptual Evaluation and Genre-Specific Training of Deep Neural Network Models of a High-Gain Guitar Amplifier
2023 - The 26th International Conference on Digital Audio Effects
Cassidy, W. J. and De Sena, E.

Summary
This paper evaluates DNN models (LSTM-RNN and WaveNet-based CNN) of a high-gain guitar amplifier using subjective listening tests, finding that genre-specific training makes the LSTM-RNN model perceptually indistinguishable from the real amplifier. All models were rated as realistic and non-inferior in preference despite minor accuracy differences.
Perception of Active Acoustics
Active Acoustic Enhancement Systems: A Review
2026 - The Journal of the Acoustical Society of America
Cassidy, W. J., De Bortoli, G. M., Prawda, K., Coleman, P., Mason, R., Lokki, T., Schlecht, S. J. and De Sena, E.

Summary
Active acoustic enhancement systems (AAESs) use microphones, loudspeakers and processing to modify a space's reverberation; this article reviews the field's modelling, topologies and research, using simulations to illustrate key conditions and outline future directions.
Naturalness of Double-Slope Decay in Generalised Active Acoustic Enhancement Systems
2024 - The 27th International Conference on Digital Audio Effects
Cassidy, W. J., Coleman, P., Mason, R. and De Sena, E.

Summary
Double-slope energy decay can be found in active acoustic systems whose artificial reverberation time (RT) significantly exceeds the natural RT of the room. This was found to significantly reduce perceived naturalness beyond an RT ratio of around two times.
Perceptual Model of Active Acoustic Enhancement Systems
2026 - Preprint, available at SSRN (link below)
Cassidy, W. J., Mason, R., Coleman, P., Lladó, P. and De Sena, E.

Summary
Linear and nonlinear models of perceived unpleasantness in active acoustic enhancement systems. Five new metrics are proposed to quantify artefacts of room acoustics, which are used to fit transient and harmonic sub-models. The metrics and models were evaluated with three listening tests.
Awards
Winners - MuseHub Hackathon
2024 - Queen Mary University of London
Awarded to Cassidy, W. J., Paterson-Stephens, L. and Strange, M. for a collision-based delay plugin developed in 24 hours.
Focusrite Prize for Technical Achievement
2023 - University of Surrey
"For the most outstanding final year technical project."
Jim Abbiss Pop Recording Prize
2023 - University of Surrey
"For the most outstanding pop recording on a final year portfolio."
AMS-Neve Portfolio Prize
2023 - University of Surrey
"For the most outstanding final year recording portfolio."
Industrial PhD
Perception and Optimisation of Active Acoustics
2023-2027 | University of Surrey, L-Acoustics
- JASA review paper for active acoustics
- First perceptual model for active acoustics
- First differentiable optimisation of active reverberation to match a target room
Programming and Software
- Python, PyTorch, NumPy - Optimisation Techniques
- MATLAB - AKtools Simulations and Plotting
- Treble SDK (Python) - Simulations
- Max MSP - Perceptual Test Design
- IBM SPSS - Statistical Analysis
- Fork, GitHub, Trello - Collaboration and Agile/Scrum
- Blender, Photoshop, Illustrator - Graphics

Presentations
- Presented over 70 slideshows at conferences, workshops, research seminar days and project meetings.
- Consolidated low-level technical material into digestible content for general audiences.

Measurements and Listening Tests
- Run full-system exponential sine sweep measurement campaigns with 6th order Ambisonics arrays
- Conducted seven perceptual experiments including MUSHRA, ABX, and novel multiple-stimulus methodologies

Audio Plugin Development
2025–2026
Ember DSP Ltd
Stratos

Transcendence

2023
Tonmeister Final-Year Coursework
Nostalgia

Skyline

2021–2022
Offensive Plugins Ltd
OX20 Spring Reverb

Glass

Mixing & Recording
Recording Engineer
2021-2022 | The Dairy Studios, Brixton
Engineering
- Performed vocal and drums editing for artists including Fontaines DC, Joesef and Joy Crookes
- Led vocal recording sessions for Swae Lee, Prince of Falls and Yazmin Lacey
- Recorded podcast material for That Peter Crouch Podcast and with Jordan Rakei
- Developed proficiency in ProTools and dialling in outboard workflows with 1073, 1176 and CL1B units.

Recording and Mixing Engineer
2024 | Freelance
Events & Volunteering
Extra Work During PhD
2023-2027 | University of Surrey
Immersive Sound & Lighting Event
- Built lighting display in reaction to spatial audio signals
- DMX programming for laser and festoon control
- Communicated with artist to help realise their vision

DAFx Website, Graphics and Organisation
- Created website, logo & animations, banners, namecards and awards for the DAFx 2024 conference

Audio Programming Workshops
- Conducted two 3-hour workshops for final-year Tonmeister undergraduate students on integrating graphics in C++ audio plugins
- Presented a tutorial on designing colourless feedback-delay networks to PhD students and post-doctoral staff


Ad Campaigns
Plugin Promo
2025-2026 | Ember DSP
One-Day Shoot
- Created a trailer, a ten-minute tutorial and five portrait reels
- Storyboarding and content planning
- Conducted interview and co-produced
- Camera operated
- Edited and colour graded
New Plugin Release
- A mixture of Blender renders, handheld video and drone footage
- Edited and graded in DaVinci Resolve
- Audio in Reaper
Hobbies
Content coming soon.
