Nova-2 Voicemail - Benchmarks & Performance - OpenTranscription

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Nova-2 Voicemail

Name: Nova-2 Voicemail
Author: Deepgram

Deepgram

Batch & Realtime

Optimized for low-bandwidth single speaker voicemail

Transcribe with this model Compare in playground

1 languages · benchmarked

Overall Score

76.7

#9 of 28

Word Error Rate

17.51%

Character Error Rate

12.36%

Match Error Rate

17.10%

Word Info Lost

22.71%

Avg Latency

954ms

Benchmarks Run

Benchmark trend

last 30 runs

Word error rate

17.51%

↓ 2.7% · 30d

5 runs ago

latest

Avg latency

954ms

↓ 22.3% · 30d

5 runs ago

latest

Cost vs. accuracy

overall WER · 28 models

Nova-2 Voicemail

field · 27 models

lower-left is better

Performance by category

8 categories

WER

lower is better

Legal

4.2%

Technical

5.5%

Medical

7.3%

Conversational

10.8%

Finance

11.3%

General

11.6%

Noisy Environment

31.3%

Code-Switching

65.3%

Category	WER	CER	MER	WIL	Latency	Benchmarks
Code-Switching	65.33%	59.99%	64.54%	69.19%	1.1s	2
Conversational	10.80%	7.10%	10.75%	13.53%	1.0s	2
Finance	11.29%	5.50%	11.21%	18.73%	1.5s	2
General	11.55%	6.36%	11.45%	18.47%	881ms	9
Legal	4.22%	1.89%	4.18%	6.18%	1.5s	2
Medical	7.28%	2.78%	6.98%	9.80%	764ms	2
Noisy Environment	31.25%	22.64%	29.58%	37.72%	707ms	4
Technical	5.50%	3.38%	5.42%	7.85%	684ms	2

Latency

p50 → p99 · 5 runs

Latency distribution

lower is better

1.6s

p50

1.7s

p90

1.7s

p95

1.7s

p99

Performance by accent

5 accents

Accent	WER	Benchmarks
African	26.15%	1
Australian	13.85%	1
Indian	26.98%	1
British	11.94%	1
American	13.21%	1

Realtime Score

75.5

TTFW (P50)

1014 ms

Flicker

10.1%

Cadence

0.8/s

RTF

1.02×

Word Error Rate

19.27%

Character Error Rate

12.34%

Benchmarks Run

Pricing

pay per second

Rate

$0.0058

/min

Per-second billing. Bring your own provider key and pay your provider directly — a 5% routing fee applies (first 100 min/mo free).

Set up BYOK

Cost estimator

1 hour

$0.35

10 hours

$3.49

100 hours

$34.92

1,000 hours

$349.20

Billed per second of audio processed.

API & usage

POST /api/v1/transcriptions

Model ID

deepgram/nova-2-voicemail

Get an API key

Authenticate every request with your secret API key as a Bearer token. Issue a key from your dashboard.

This model also supports realtime streaming over WebSocket.

Quickstart

Upload your audio, create a job with this model, then poll the job or set a webhook_url to be notified when it completes.

# 1. Request a signed upload URL
curl https://opentranscription.io/api/v1/uploads \
  -H "Authorization: Bearer $OT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "file_name": "interview.mp3", "file_size": 3456789, "mime_type": "audio/mpeg" }'
# → { "upload_url": "...", "file_path": "...", "expires_at": "..." }

# 2. Upload the audio bytes to the signed URL
curl -X PUT "$UPLOAD_URL" --upload-file interview.mp3

# 3. Create the transcription job
curl https://opentranscription.io/api/v1/transcriptions \
  -H "Authorization: Bearer $OT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "file_path": "$FILE_PATH",
    "model": "deepgram/nova-2-voicemail",
    "language": "en",
    "webhook_url": "https://your-app.com/webhooks/ot"
  }'
# → we POST a signed event to your webhook_url when the job finishes — no polling required

Key parameters

file_path

string

required

Storage path returned by the upload step.

model

string

required

The model to run this job on.

language

string

ISO 639-1 language code. Omit to auto-detect.

webhook_url

string

HTTPS URL notified with the result when the job completes. Delivered events are signed (X-OT-Signature).

Response

A completed job returns the transcript in the OpenTranscription Unified Schema (OTUS).

{
  "id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "status": "completed",
  "transcript": {
    "text": "Welcome to the meeting, everyone.",
    "language": "en",
    "confidence": 0.97,
    "segments": [
      {
        "id": 0,
        "start": 0,
        "end": 3.5,
        "text": "Welcome to the meeting, everyone."
      }
    ],
    "words": [
      {
        "word": "Welcome",
        "start": 0,
        "end": 0.42,
        "confidence": 0.99
      }
    ]
  }
}

Webhooks — skip polling

We POST a signed event to your webhook_url when a job completes or fails; verify the X-OT-Signature (HMAC-SHA256, reject if older than 300 s) and dedupe on the event id, then fetch the full transcript via GET /api/v1/transcriptions/{id}.

# We POST a signed event to your webhook_url when a job finishes.
# Headers:
#   X-OT-Signature: t=1736937042,v1=5257a869e7eceb6c6c2c2a1b4d6e9f8c2a1b4d6e9f8c2a1b4d6e9f8c2a1b4d6e
#   X-OT-Event-Id: evt_9f8c2a1b4d6e
#   X-OT-Event-Type: transcription.completed
#
# Body (thin event — fetch the transcript with GET /transcriptions/{data.id}):
{
  "id": "evt_9f8c2a1b4d6e",
  "event": "transcription.completed",
  "created": "2025-01-15T10:30:42.000Z",
  "data": {
    "id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
    "status": "completed",
    "error_code": null
  }
}
#
# Verify: HMAC-SHA256 over "<t>.<raw_body>" with your signing secret,
# constant-time compare against any v1, and reject if |now - t| > 300s.

Rate-limited per tier — see the X-RateLimit-* response headers.

Full API reference

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Supported Languages

English

Supported Formats

mp3wavflacm4aoggwebm

Features

Code-switchingWord TimestampsCustom Vocabulary

Nova-2 Voicemail

Benchmark trend

Cost vs. accuracy

Performance by category

Latency

Performance by accent

Pricing

API & usage

Similar models

About Nova-2 Voicemail