CekuraBench

Cartesia Sonic 3.5vsDeepgram Flux

Cartesia Sonic 3.5Deepgram Flux
Compare

Speed and accuracy

Left is faster. Higher reads more hard parts right.

Fast and accurate60%70%80%90%100%00.5s1s1.5s2sTime until the caller hears the voice
  • Cartesia Sonic 3.5261 ms · 73.1%
  • Deepgram Flux194 ms · 77.4%

Cartesia Sonic 3.5 is better on naturalness and price. Deepgram Flux is better on non-streaming latency, streaming latency, stopping and accuracy.

Last updated Methodology by Dileep Chagam

Which is better at what

Measure by measure, the same sentences, the same place.

MeasureCartesia Sonic 3.5Deepgram Flux
  • Non-streaming latency (median)Deepgram Flux is better261 ms194 ms
  • Streaming latency (median)Deepgram Flux is better244 ms154 ms
  • Extra audio after a stopDeepgram Flux is better809 ms80 ms
  • Hard parts read rightDeepgram Flux is better73.1%77.4%
  • Naturalness (1 to 5)Cartesia Sonic 3.5 is better4.414.16
  • Price per 1M charactersCartesia Sonic 3.5 is better$39.20$45.00
Hard parts read rightCartesia Sonic 3.5Deepgram Flux
  • Numbers and shorthand7 a.m. · 20% · 36°F · approx.69%72%
  • Codes and addressesSAVE20 · help@north-clinic.org · 1-800-555-019975%81%
  • Read from contextSt. Mary's on Main St. · Dr. Okafor54%69%
  • Medical termslevothyroxine · gastroenterology97%97%

An estimate: speech-to-text transcribers scored it, not people.

Hear both

The same sentence, read by each voice.

19 sentences, the same for both
  1. 01A greetingThanks for calling Cedar Valley Family Practice, this is Riley. How can I help you today?
  2. 02MoneyYour current balance is $1,347.09.
  3. 03A dateThe order was placed on 2026-03-14 and shipped two days later.
  4. 04Tracking codeThe tracking number is 1Z 7A4 X29 0341 8867.
  5. 05Email addressI have m.rivera88@example.org, is that still current?
  6. 06An Irish nameSiobhan Ó Briain called about the invoice.

How each ranks among all 26

MeasureCartesia Sonic 3.5Deepgram Flux
  • Non-streaming latency (median)8 of 266 of 26
  • Streaming latency (median)10 of 186 of 18
  • Extra audio after a stop6 of 64 of 6
  • Hard parts read right24 of 2619 of 26
  • Naturalness (1 to 5)14 of 2626 of 26
  • Price per 1M characters16 of 2521 of 25

Related comparisons

Cartesia Sonic 3.5 vs Deepgram Flux FAQ

  • Deepgram Flux. Cartesia Sonic 3.5: 261 ms. Deepgram Flux: 194 ms.

  • Deepgram Flux. Cartesia Sonic 3.5: 244 ms. Deepgram Flux: 154 ms.

  • Deepgram Flux. Cartesia Sonic 3.5: 809 ms. Deepgram Flux: 80 ms.

  • Deepgram Flux. Cartesia Sonic 3.5: 73.1%. Deepgram Flux: 77.4%.

  • Cartesia Sonic 3.5. Cartesia Sonic 3.5: $39.20. Deepgram Flux: $45.00.