Evaluating Podcast Recommendations with Profile-Aware LLM-as-a-Judge
Authors: name: Francesco Fabbri; name: Gustavo Penha; name: Edoardo D'Amico; name: Alice Wang; name: Marco De Nadai; name: Jackie Doremus; name: Paul Gigioli; name: Andreas Damianou; name: Oskar Stal; name: Mounia Lalmas
Published: 2025-08-12 09:23:35

Abstract: Evaluating personalized recommendations remains a central challenge,
especially in long-form audio domains like podcasts, where traditional offline
metrics suffer from exposure bias and online methods such as A/B testing are
costly and operationally constrained. In this paper, we propose a novel
framework that leverages Large Language Models (LLMs) as offline judges to
assess the quality of podcast recommendations in a scalable and interpretable
manner. Our two-stage profile-aware approach first constructs natural-language
user profiles distilled from 90 days of listening history. These profiles
summarize both topical interests and behavioral patterns, serving as compact,
interpretable representations of user preferences. Rather than prompting the
LLM with raw data, we use these profiles to provide high-level, semantically
rich context-enabling the LLM to reason more effectively about alignment
between a user's interests and recommended episodes. This reduces input
complexity and improves interpretability. The LLM is then prompted to deliver
fine-grained pointwise and pairwise judgments based on the profile-episode
match. In a controlled study with 47 participants, our profile-aware judge
matched human judgments with high fidelity and outperformed or matched a
variant using raw listening histories. The framework enables efficient,
profile-aware evaluation for iterative testing and model selection in
recommender systems.