HiMMP Heaviness Lab
Hearing hardness and punch in real metal mixes
Compare nine mixes, play with stems, and see why some versions feel heavier than others
The HiMMP Heaviness Lab is an interactive demonstration of how metal production techniques shape the perception of heaviness. Using a "one song, many mixes" design and psychoacoustic modelling, it shows how acoustic hardness and punch contribute to heaviness, and how producers trade them off in real projects. Start by listening, then explore the stems and the data.
Who is this for?
Producers & Engineers
- Compare nine world-class mixes of the same song
- Solo and balance stems for drums, bass, guitars, and vocals
- Hear how hardness, punch, and dynamics shape heaviness in practice
Students & Educators
- Use guided listening tasks to introduce psychoacoustic concepts
- Connect listening examples to visualizations and simple models
- Integrate the Lab with seminars on production, perception, and analysis
Researchers
- Inspect the stimuli used in our psychoacoustic studies
- Explore relationships between acoustic hardness, punch, and perceived heaviness
- Link directly to methodological details and related publications
More ways to explore
🎸 Compare Stems
A/B compare individual instruments across all nine producers
📖 Theory
Understand the ecological perception and hardness model
🎵 About the Song
Learn about "In Solitude" and its design
🔬 Methodology
Study design, participants, and analysis
📦 Downloads
Audio packs, figures, and supplementary materials
ℹ️ About & Credits
Project team, funder, and acknowledgements
What you are hearing
The Lab is based on two empirical studies. In a production study, nine internationally recognised metal producers created full mixes and stems of the same song. In two listening tests, participants rated segments of these mixes on heaviness and punch, while acoustic models estimated hardness and dynamic range.
Across all mixes and stems, acoustic hardness (spectral-textural density) explains a large proportion of the variance in perceived heaviness (r ≈ .775, R² ≈ .60), with punch (temporal impact) playing a secondary, asymmetrical role. The Lab turns these findings into guided listening tasks that connect models, measurements, and musical experience.