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Deepgram Aura 2 Deepgram · text-to-speech (TTS) API

Visible delay

266 ms median and 526 ms P95 time to first audio on Coval (30 days to October 22, 2026): Visible delay speed tier.

Benchmark summary: Visible delay speed tier on Coval's P95 (the voice becomes a visible part of the delay).

Deepgram Aura 2 is a proprietary text-to-speech (TTS) API from Deepgram, measured by two independent benchmarks: Coval and Speko.

Speed tier

Visible delay

P95 of 320 ms or more. The voice becomes a visible part of the delay.

Median time to first audioCoval, 30 days
266 ms
P95 time to first audio (slow turns)Coval, 30 days
526 ms
Naturalness EloSpeko
1584
Listener Elo (95% interval)Artificial Analysis
not rated
Numbers and dates (0 to 1)Speko
0.2
List price per 1M charactersall sources
$30

Data read October 22, 2026. No combined score: methodology

Gradium TTS vs Deepgram Aura 2 Fastest TTS APIs, by speed tier

Speed

On Coval's 30-day window ending October 22, 2026 (3,308 runs from US East), Deepgram Aura 2 starts speaking after 266.4 ms on a typical turn (median) and 526.2 ms on a slow turn (P95, the slowest one in twenty). That P95 is 23rd lowest of the 32 models Coval measures, which puts it in the Visible delay tier: the voice becomes a visible part of the delay. On the median it is a tie (gap under 10 ms) with Rime Mist v3, Soniox TTS Real-Time v2 and Soniox TTS RT v1. Speko's board plots it at 147 ms time to first audio from US East; its model page reports a 125 ms sweep.

Voice quality

Speko rates its naturalness at 1,584 Elo from blind A/B votes on phone-agent lines (9th highest of the 43 models Speko rates).

Numbers and dates

Speko's pronunciation test on numbers, dates and currency scores it 0.2 on a 0-to-1 scale (25th highest of the 30 models Speko scores). This is the accuracy measure used here; Coval's word error rate separates models too little to compare them.

Price

Coval lists $30 per 1M characters (since Aug 10, 2026). Speko lists about $30. List prices, as each source prints them.

Languages tested

Tested in Spanish, German and French by Artificial Analysis or Speko. A language missing here was not tested, which does not mean it is unsupported.

Benchmark measurements

Latency and accuracy — Coval (30-day window)

Mean TTFA
300.3 ms
P50 / median time-to-first-audio (TTFA)
266.4 ms
P90 TTFA
491.6 ms
P95 TTFA
526.2 ms
Latency consistency (standard deviation)
142.1 ms
Leading silence
190.5 ms
Time to first byte (network arrival)
109.8 ms
Accuracy: word error rate (WER)
2.2%
WER basis
pooled
Latency runs
3,308 runs
Accuracy runs
3,306 runs
Window
30d
Coval snapshot
2026-10-22T14:00:19.256741Z
Coval model ID
aura-2-thalia-en
Coval model page
benchmarks.coval.ai
List price per 1M characters
30 USD
Price listed since
Aug 10, 2026

Speko

P50 TTFA, US East
125 ms
Naturalness (Elo)
1,584
Head-to-head win rate
65%
Pronunciation robustness (0 to 1)
0.2
Voice drift (lower is steadier)
9
Price per 1M characters
30 USD
Measured on
2026-07-03
Speko model
aura-2
Speko model page
benchmarks.speko.ai
Time to first audio, board chart
147 ms

Price (all sources)

Lowest list price per 1M characters
30 USD
Highest list price per 1M characters
30 USD

Not collected

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