Large audio-language models (LALMs) describe audio at the clip level but cannot assign timestamps to the events, speakers, or sounds they identify. Despite being essential for downstream tasks like speech recognition and dense audio captioning, timestamping remains a key limitation of most LALMs. We present TEMPO (Temporally-grounded Multi-task Post-training), the first unified model to handle audio, speech, and music timestamping tasks. Our core contribution is a supervised fine-tuning (SFT) stage built on three innovations: atomic timestamp tokens, a time-aware projector that injects sinusoidal wall-clock encodings into audio frame embeddings, and a distance-aware Gaussian loss. Our training is based on a synthetic-to-real curriculum. We further introduce, to our knowledge, the first application of reinforcement learning to unified audio timestamping, using GRPO with verifiable temporal rewards that directly optimize the evaluation objectives. Rather than serving as the primary source of performance gains, GRPO acts as a refinement stage on top of the SFT checkpoint, providing modest additional improvements. To support this work, we build a training dataset containing 119K samples and an evaluation benchmark containing 10K samples, drawn from established corpora across five tasks. On this benchmark, TEMPO outperforms Audio Flamingo Next and Qwen3-Omni, two state-of-the-art LALMs explicitly trained on timestamped data. Experiments confirm that SFT delivers most of these gains, with GRPO providing consistent but moderate refinements.

In many real-world settings like journalism, law, medicine, and science communication, information is passed from one person or system to another through multiple rounds of summarization or rewriting. This process, known as multi-hop information transfer, also happens increasingly in workflows involving large language models (LLMs). But while summarization models and factuality metrics have improved, we still don’t fully understand how meaning and factual accuracy hold up across long chains of transformations, especially when both humans and LLMs are involved.In this paper, we take a fresh look at this problem by combining insights from cognitive science (Bartlett’s serial reproduction) and information theory (Shannon’s noisy-channel model). We build a new dataset of 700 five-step transmission chains that include human-only, LLM-only, mixed human-LLM, and cross-LLM settings across a wide range of source texts. To track how meaning degrades, we introduce three new metrics: Information Degradation Rate (IDR) for semantic drift, Meaning Preservation Entropy (MPE) for uncertainty in factual content, and Cascaded Hallucination Propagation Index (CHPI) for how hallucinations accumulate over time. Our findings reveal that hybrid chains behave asymmetrically. When a human summary is refined by a language model, the final output tends to preserve meaning well, suggesting that models can improve upon human-written summaries. The code and data will be available at : https://github.com/transtrace6/TransTrace.git.