JAM: A Tiny Flow-based Song Generator with Fine-grained Controllability
  and Aesthetic Alignment
Authors: name: Renhang Liu; name: Chia-Yu Hung; name: Navonil Majumder; name: Taylor Gautreaux; name: Amir Ali Bagherzadeh; name: Chuan Li; name: Dorien Herremans; name: Soujanya Poria
Published: 2025-07-28 14:34:02

Abstract: Diffusion and flow-matching models have revolutionized automatic
text-to-audio generation in recent times. These models are increasingly capable
of generating high quality and faithful audio outputs capturing to speech and
acoustic events. However, there is still much room for improvement in creative
audio generation that primarily involves music and songs. Recent open
lyrics-to-song models, such as, DiffRhythm, ACE-Step, and LeVo, have set an
acceptable standard in automatic song generation for recreational use. However,
these models lack fine-grained word-level controllability often desired by
musicians in their workflows. To the best of our knowledge, our
flow-matching-based JAM is the first effort toward endowing word-level timing
and duration control in song generation, allowing fine-grained vocal control.
To enhance the quality of generated songs to better align with human
preferences, we implement aesthetic alignment through Direct Preference
Optimization, which iteratively refines the model using a synthetic dataset,
eliminating the need or manual data annotations. Furthermore, we aim to
standardize the evaluation of such lyrics-to-song models through our public
evaluation dataset JAME. We show that JAM outperforms the existing models in
terms of the music-specific attributes.