Inworld TTS-2vsAssemblyAI TTS 1
Speed and accuracy
Left is faster. Higher reads more hard parts right.
- Inworld TTS-2126 ms · 93.4%
- AssemblyAI TTS 1171 ms · 81.5%
Inworld TTS-2 is better on non-streaming latency, streaming latency, accuracy and naturalness. AssemblyAI TTS 1 is better on stopping and price.
Last updated Methodology by Dileep Chagam
Which is better at what
Measure by measure, the same sentences, the same place.
- Non-streaming latency (median)Inworld TTS-2 is better126 ms171 msInworld TTS-2
- Streaming latency (median)Inworld TTS-2 is better127 ms159 msInworld TTS-2
- Extra audio after a stopAssemblyAI TTS 1 is betterNo stop message40 msAssemblyAI TTS 1
- Hard parts read rightInworld TTS-2 is better93.4%81.5%Inworld TTS-2
- Naturalness (1 to 5)Inworld TTS-2 is better4.524.50Inworld TTS-2
- Price per 1M charactersAssemblyAI TTS 1 is better$25.00$15.00AssemblyAI TTS 1
- Numbers and shorthand7 a.m. · 20% · 36°F · approx.93%74%Inworld TTS-2
- Codes and addressesSAVE20 · help@north-clinic.org · 1-800-555-019986%92%AssemblyAI TTS 1
- Read from contextSt. Mary's on Main St. · Dr. Okafor100%71%Inworld TTS-2
- Medical termslevothyroxine · gastroenterology99%100%AssemblyAI TTS 1
An estimate: speech-to-text transcribers scored it, not people.
Hear both
The same sentence, read by each voice.
- 01A greetingThanks for calling Cedar Valley Family Practice, this is Riley. How can I help you today?
- 02MoneyYour current balance is $1,347.09.
- 03A dateThe order was placed on 2026-03-14 and shipped two days later.
- 04Tracking codeThe tracking number is 1Z 7A4 X29 0341 8867.
- 05Email addressI have m.rivera88@example.org, is that still current?
- 06An Irish nameSiobhan Ó Briain called about the invoice.
How each ranks among all 27
- Non-streaming latency (median)3 of 274 of 27
- Streaming latency (median)5 of 198 of 19
- Extra audio after a stopn/a3 of 7
- Hard parts read right1 of 2714 of 27
- Naturalness (1 to 5)2 of 274 of 27
- Price per 1M characters11 of 262 of 26
Inworld TTS-2 vs AssemblyAI TTS 1 FAQ
Which starts talking sooner, Inworld TTS-2 or AssemblyAI TTS 1?
Inworld TTS-2. Inworld TTS-2: 126 ms. AssemblyAI TTS 1: 171 ms.
Inworld TTS-2. Inworld TTS-2: 126 ms. AssemblyAI TTS 1: 171 ms.
Inworld TTS-2. Inworld TTS-2: 127 ms. AssemblyAI TTS 1: 159 ms.
AssemblyAI TTS 1. Inworld TTS-2: No stop message. AssemblyAI TTS 1: 40 ms.
Inworld TTS-2. Inworld TTS-2: 93.4%. AssemblyAI TTS 1: 81.5%.
AssemblyAI TTS 1. Inworld TTS-2: $25.00. AssemblyAI TTS 1: $15.00.
Test your voice agent the same way.
Cekura runs these simulated calls on your agent and scores every one.