---
license: cc-by-4.0
language:
- en
library_name: nemo
pipeline_tag: automatic-speech-recognition
tags:
- asr
- speech-recognition
- parakeet
- nemo
- adapter
- linear-adapter
- switchboard
- telephony
base_model: nvidia/parakeet-tdt_ctc-110m
datasets:
- hhoangphuoc/switchboard
metrics:
- wer
---

# Parakeet-TDT-CTC-110M — Switchboard LinearAdapter

A lightweight **LinearAdapter** (2.25M trainable params, dim=128) fine-tuned on
top of the **frozen** [`nvidia/parakeet-tdt_ctc-110m`](https://huggingface.co/nvidia/parakeet-tdt_ctc-110m)
for conversational telephone speech. The base model's 114.6M weights are
untouched — this file is **only the ~9.5 MB adapter**.

## Results — Switchboard test

| model | WER | utterances | audio |
|---|---|---|---|
| base `parakeet-tdt_ctc-110m` | 15.98% | 50,165 | 63.4 h |
| **+ this adapter** | **7.00%** | 50,165 | 63.4 h |

**−8.98 WER absolute / 56% relative** on the public `hhoangphuoc/switchboard`
test split (650,491 reference words; 23,703 sub / 9,284 ins / 12,577 del).

> **Off-domain caveat (important):** this is a telephony *specialist*. On
> clean read speech it **regresses** (LibriSpeech WER ~4.96% vs ~2.61% base).
> Use it for conversational/telephone audio, not general ASR.

## Usage (NeMo)

```python
import nemo.collections.asr as nemo_asr
m = nemo_asr.models.ASRModel.from_pretrained("nvidia/parakeet-tdt_ctc-110m")
m.load_adapters("switchboard_adapter.nemo")   # this file
m.set_enabled_adapters("switchboard", enabled=True)
print(m.transcribe(["call.wav"]))   # 16 kHz mono
```

## Training

- Base: `nvidia/parakeet-tdt_ctc-110m` (frozen, 114.6M params)
- Adapter: `LinearAdapter`, dim 128, 2,245,632 trainable params
- 50 epochs, effective batch 32, LR 5e-4, CosineAnnealing (500 warmup),
  bf16-mixed, grad-clip 1.0; best val WER 0.0687 @ epoch 4; ~6.8 h on one GPU.
- Data: Switchboard (LDC; not redistributed here).

## License / attribution

Adapter weights: CC-BY-4.0. Requires the base model
`nvidia/parakeet-tdt_ctc-110m` (NVIDIA, CC-BY-4.0) — load it from NVIDIA and
apply this adapter on top. This repo does **not** redistribute NVIDIA's weights.