Voice quality benchmark

Methodology by Shashij Gupta

Nine agents. The same ten scenarios. 270 live calls scored across voice quality, turn taking, latency, and reliability.

9
production agents
10
scenarios
270
live calls
10
quality metrics
Quality against response timeThe tradeoff
Best trade-off zoneBest trade-off frontier
Quality composite
Median turn latency

The three fastest agents are also the three highest scoring. Cognigy is both the slowest at 3.76s and the lowest at 73.7.

Leaderboard

Conversation quality ranking

Scores marked /5 are qualitative (higher is better); % values are pass rates. Latency and stop time are in seconds, lower is better.

How the composite is calculated

The ten metrics are normalized to 0 to 100 and averaged with equal weight. Qualitative scores are scaled against 5, pass rates use their percentage, and lower latency ranks higher.

  • 1Bland92.8
    Humanness 4.13Voice tone 4.30Interruption 4.61Latency 2.62sStop time 0.62s
  • 2Retell92.2
    Humanness 3.57Voice tone 4.15Interruption 4.90Latency 2.38sStop time 2.74s
  • 3Cresta90.1
    Humanness 3.60Voice tone 4.06Interruption 4.97Latency 2.78sStop time 1.56s
  • Humanness 3.93Voice tone 4.08Interruption 5.00Latency 3.08sStop time 1.23s
  • 5Decagon87.4
    Humanness 3.60Voice tone 4.23Interruption 4.81Latency 3.13sStop time 1.76s
  • 6Sierra85.5
    Humanness 3.63Voice tone 3.81Interruption 4.67Latency 3.42sStop time 1.06s
  • 7PolyAI82.6
    Humanness 3.73Voice tone 4.22Interruption 3.68Latency 2.99sStop time 3.97s
  • 8Vapi78.3
    Humanness 3.47Voice tone 3.38Interruption 4.52Latency 3.34sStop time 5.34s
  • 9Cognigy73.7
    Humanness 3.60Voice tone 3.92Interruption 4.65Latency 3.76sStop time 7.55s
Metric by metric

Every metric, side by side

Compare every agent across the same ten measures.

Humanness
ProviderHigher is better
1Bland4.13
2ElevenLabs3.93
3PolyAI3.73
4Sierra3.63
5Cresta3.60
6Decagon3.60
7Cognigy3.60
8Retell3.57
9Vapi3.47
Voice tone + clarity
ProviderHigher is better
1Bland4.30
2Decagon4.23
3PolyAI4.22
4Retell4.15
5ElevenLabs4.08
6Cresta4.06
7Cognigy3.92
8Sierra3.81
9Vapi3.38
Interruption score
ProviderHigher is better
1ElevenLabs5.00
2Cresta4.97
3Retell4.90
4Decagon4.81
5Sierra4.67
6Cognigy4.65
7Bland4.61
8Vapi4.52
9PolyAI3.68
No unnecessary repetition
ProviderHigher is better
1Retell5.00
2ElevenLabs4.97
3Vapi4.92
4Cognigy4.91
5Bland4.74
6Cresta4.72
7Sierra4.70
8Decagon4.59
9PolyAI4.53
Relevancy
ProviderHigher is better
1Retell100%
2Cresta100%
3ElevenLabs100%
4Decagon100%
5Sierra100%
6PolyAI100%
7Vapi100%
8Cognigy100%
9Bland95%
Response consistency
ProviderHigher is better
1Bland100%
2Retell100%
3Cresta100%
4ElevenLabs100%
5Decagon100%
6Sierra100%
7Vapi100%
8Cognigy100%
9PolyAI95%
Gibberish free
ProviderHigher is better
1Retell100%
2ElevenLabs100%
3Decagon100%
4Sierra100%
5PolyAI100%
6Vapi100%
7Cognigy100%
8Cresta97%
9Bland95%
Infrastructure clean
ProviderHigher is better
1Bland100%
2Retell100%
3Cresta100%
4ElevenLabs100%
5Decagon100%
6Sierra100%
7PolyAI100%
8Vapi95%
9Cognigy95%
Median turn latency
ProviderLower is better
1Retell2.38s
2Bland2.62s
3Cresta2.78s
4PolyAI2.99s
5ElevenLabs3.08s
6Decagon3.13s
7Vapi3.34s
8Sierra3.42s
9Cognigy3.76s
Stop time after interruption
ProviderLower is better
1Bland0.62s
2Sierra1.06s
3ElevenLabs1.23s
4Cresta1.56s
5Decagon1.76s
6Retell2.74s
7PolyAI3.97s
8Vapi5.34s
9Cognigy7.55s
Per agent detail

Every agent, every metric

Open each agent for the full ten metric snapshot and the run review observation.

01BlandProduction voice agent+

Metric snapshot · three run average

Composite
92.8
Humanness
4.13
Voice tone + clarity
4.30
Interruption score
4.61
No repetition score
4.74
Relevancy
95%
Response consistency
100%
Gibberish clean
95%
Infrastructure clean
100%
Median latency
2.62s
Stop time after barge in
0.62s
Observed in run review

Highest composite. Led humanness (4.13) and the quickest barge in recovery in the field (0.62s, averaged across every interruption) with fast turns. A couple of relevancy and gibberish edge cases were the only blemishes.

02RetellProduction voice agent+

Metric snapshot · three run average

Composite
92.2
Humanness
3.57
Voice tone + clarity
4.15
Interruption score
4.90
No repetition score
5.00
Relevancy
100%
Response consistency
100%
Gibberish clean
100%
Infrastructure clean
100%
Median latency
2.38s
Stop time after barge in
2.74s
Observed in run review

The cleanest reliability sheet in the field: perfect relevancy, consistency, gibberish and infrastructure, zero unnecessary repetition, the fastest turns, and a solid 2.74s barge in recovery once first message overlaps are excluded.

03CrestaProduction voice agent+

Metric snapshot · three run average

Composite
90.1
Humanness
3.60
Voice tone + clarity
4.06
Interruption score
4.97
No repetition score
4.72
Relevancy
100%
Response consistency
100%
Gibberish clean
97%
Infrastructure clean
100%
Median latency
2.78s
Stop time after barge in
1.56s
Observed in run review

Second-best interruption handling (4.97) with fast, clean turns and a quick 1.56s barge in recovery. A few gibberish edge cases were the only mark against it.

04ElevenLabsProduction voice agent+

Metric snapshot · three run average

Composite
90.0
Humanness
3.93
Voice tone + clarity
4.08
Interruption score
5.00
No repetition score
4.97
Relevancy
100%
Response consistency
100%
Gibberish clean
100%
Infrastructure clean
100%
Median latency
3.08s
Stop time after barge in
1.23s
Observed in run review

Perfect interruption score (5.0), near-perfect no repetition, a fully clean reliability sheet, and a quick 1.23s barge in recovery. Mid-pack latency is the main thing left to improve.

05DecagonProduction voice agent+

Metric snapshot · three run average

Composite
87.4
Humanness
3.60
Voice tone + clarity
4.23
Interruption score
4.81
No repetition score
4.59
Relevancy
100%
Response consistency
100%
Gibberish clean
100%
Infrastructure clean
100%
Median latency
3.13s
Stop time after barge in
1.76s
Observed in run review

A clean sheet on every reliability metric with strong voice tone (4.23) and a quick 1.76s barge in recovery. Mid-pack latency keeps it just outside the top group.

06SierraProduction voice agent+

Metric snapshot · three run average

Composite
85.5
Humanness
3.63
Voice tone + clarity
3.81
Interruption score
4.67
No repetition score
4.70
Relevancy
100%
Response consistency
100%
Gibberish clean
100%
Infrastructure clean
100%
Median latency
3.42s
Stop time after barge in
1.06s
Observed in run review

A clean reliability sheet and the second-quickest barge in recovery (1.06s), but the lowest voice tone clarity in the upper group and the slowest turns (3.42s) hold it mid pack.

07PolyAIProduction voice agent+

Metric snapshot · three run average

Composite
82.6
Humanness
3.73
Voice tone + clarity
4.22
Interruption score
3.68
No repetition score
4.53
Relevancy
100%
Response consistency
95%
Gibberish clean
100%
Infrastructure clean
100%
Median latency
2.99s
Stop time after barge in
3.97s
Observed in run review

Strong voice tone and a near clean reliability sheet, but the weakest interruption handling in the field (3.68) and a slow ~4s barge in recovery pull the composite down.

08VapiProduction voice agent+

Metric snapshot · three run average

Composite
78.3
Humanness
3.47
Voice tone + clarity
3.38
Interruption score
4.52
No repetition score
4.92
Relevancy
100%
Response consistency
100%
Gibberish clean
100%
Infrastructure clean
95%
Median latency
3.34s
Stop time after barge in
5.34s
Observed in run review

Low unnecessary repetition (4.92), but the lowest voice tone clarity in the field (3.38) and a slow 5.34s barge in recovery place it near the bottom of this quality slice.

09CognigyProduction voice agent+

Metric snapshot · three run average

Composite
73.7
Humanness
3.60
Voice tone + clarity
3.92
Interruption score
4.65
No repetition score
4.91
Relevancy
100%
Response consistency
100%
Gibberish clean
100%
Infrastructure clean
95%
Median latency
3.76s
Stop time after barge in
7.55s
Observed in run review

Solid interruption score and low repetition, but the slowest latency (3.76s) and by far the slowest barge in recovery in the field (7.55s across 21 interruptions), plus an infrastructure edge case, place it last.

How it works

Methodology

  1. 01

    Same scenarios

    Every agent received the same ten difficult caller scenarios.

  2. 02

    Three repeats

    Each scenario ran three times on the agent's public phone line.

  3. 03

    One scorecard

    Ten voice, turn taking, latency, and reliability metrics were averaged.

Score your own production agent the same way

Run the same ten-metric scorecard on your production number.

Frequently asked questions

What exactly was tested?+

Nine real production voice agents, each running on a different platform (Bland, Retell, Cresta, Decagon, ElevenLabs, PolyAI, Sierra, Cognigy, Vapi), reached on their live public phone lines. Every agent got the same ten conditional action scenarios and the same simulated caller personality, three times each, 270 live calls in total.

How is the composite computed?+

Each of the ten metrics is normalized direction aware (higher is better metrics against their scale; latency and stop time inverted because lower is better), then averaged into a 0 to 100 composite. Boolean reliability metrics are counted as their pass rate.

Is this a fair, apples-to-apples comparison?+

The test harness is identical for every agent: same scenarios, same caller personality, same metrics, same three repetitions; only the phone number differs. Because each agent operates in a different business domain, residual domain effects can't be fully removed, so read the ranking as indicative rather than a definitive verdict on any platform.

Can I run this on my own production agent?+

Yes. This is exactly what Cekura does for its customers: probe a live agent, score it on these metrics from real calls, and retest after each prompt or config change so quality moves in the right direction. You can point Cekura at your own number and get the same scorecard.