---
language:
- en
license: apache-2.0
tags:
- audio
- medical
- cardiopulmonary
- auscultation
- instruction-tuning
- lora
- medgemma
base_model: google/medgemma-4b-it
datasets:
- askyishan/StethoBench
---

# StethoLM

**StethoLM** is the first audio–language model specialized for cardiopulmonary auscultation, capable of performing instruction-driven clinical tasks across the full spectrum of auscultation analysis. It integrates a cardiopulmonary audio encoder with a medical language model backbone, trained on [StethoBench](https://huggingface.co/datasets/askyishan/StethoBench) — a comprehensive benchmark of 77,027 instruction–response pairs from 16,125 labeled recordings.

This work is published in the Transactions on Machine Learning Research (TMLR).

---

## Model Description

StethoLM connects a **COLA audio encoder** (EfficientNet-based, pre-trained on cardiopulmonary sounds via [CaReAQA](https://arxiv.org/abs/2505.01199)) to **MedGemma-4B-IT** via a learned MLP prefix projector. The audio is encoded into a short sequence of prefix tokens that are prepended to the text input of the language model. All components — audio encoder, prefix projector, and language model (via LoRA) — are jointly fine-tuned end-to-end.

**Architecture:**
- **Audio encoder:** COLA (EfficientNet backbone), pre-trained on cardiopulmonary audio, outputs 1280-dim embeddings; **fine-tuned** during StethoLM training
- **Prefix projector:** 3-layer MLP mapping audio features to 4 LM prefix tokens
- **Language model backbone:** [google/medgemma-4b-it](https://huggingface.co/google/medgemma-4b-it) fine-tuned with LoRA (r=8, α=32)

**Training:**
- **Stage 1:** Supervised fine-tuning (SFT) on StethoBench training split
- **Stage 2:** Multimodal Direct Preference Optimization (mDPO) with audio degradation-based conditional preference

---

## Intended Use

StethoLM is designed for **research** on AI-assisted cardiopulmonary auscultation. It supports seven clinical task categories:

| Task | Description |
|------|-------------|
| **Classification** | Binary normal/abnormal classification |
| **Identification** | Identifying specific sound types (e.g., wheezing, crackles) |
| **Report** | Generating a structured auscultation report |
| **Reasoning** | Explaining clinical findings |
| **Differential Diagnosis (DDx)** | Listing possible diagnoses |
| **Comparison** | Comparing findings across recordings |
| **Location** | Identifying anatomical auscultation site |

> ⚠️ **Not for clinical use.** This model is intended for research purposes only and has not been validated for clinical decision-making.

---

## How to Use

This repository contains the **adapter weights** (fine-tuned audio encoder + LoRA adapters + prefix projector, ~713 MB). The base MedGemma-4B model is downloaded automatically from HuggingFace on first run.

### 1. Clone the code repository

```bash
git clone https://github.com/askyishan/StethoLM
cd StethoLM
pip install -r requirements.txt
```

### 2. Download the adapter checkpoint

```bash
huggingface-cli download askyishan/StethoLM stetholm_adapter.pt --local-dir checkpoints/
```

### 3. Run inference

```bash
python predict.py \
    --input_jsonl data/stethobench.jsonl \
    --output_jsonl predictions.jsonl \
    --audio_dir /path/to/audio_files \
    --checkpoint checkpoints/stetholm_adapter.pt \
    --model_name google/medgemma-4b-it \
    --audio_encoder cola \
    --split test
```

---

## Training Data

StethoLM was trained on [StethoBench](https://huggingface.co/datasets/askyishan/StethoBench). The training split comprises recordings from 7 in-domain datasets; 4 additional datasets are held out as out-of-distribution (OOD) test sets.

**In-domain training datasets:**

| Dataset | Domain |
|---------|--------|
| CirCor DigiScope (heart-circor) | Heart |
| SPRSound (spr) | Lung |
| COVID-UK (coviduk) | Cough |
| CoughVid (coughvid) | Cough |
| ICBHI (icbhi) | Lung |
| ZCHSound (heart-zch) | Heart |
| KAUH (kauh) | Cardiopulmonary |

**Out-of-distribution (OOD) test datasets:**

| Dataset | Domain |
|---------|--------|
| BMD-HS | Heart |
| CINC | Cardiopulmonary |
| TR | Lung |
| FluSense | Cough |

---

## Citation

If you use StethoLM or StethoBench in your research, please cite:

```bibtex
@article{stetholm2025,
  title     = {StethoLM: An Audio–Language Model for Cardiopulmonary Auscultation},
  author    = {},
  journal   = {Transactions on Machine Learning Research},
  year      = {2025},
  url       = {https://huggingface.co/askyishan/StethoLM}
}
```