1 Best Practices for Voice Authentication Charles R. Jankowski Jr., Ph. D. SpeechTek West 2007 February 21, 2007

2 Design for Voice Authentication Dialog design is the single most critical aspect of voice authentication performance

3 Make Verifier SECURE Make Verifier EASY to use Verifier Dialog and Application Design

4 Verifier Performance Measures Automation Rate –Percentage of repeat true speakers automated by system –100 – False Reject Rate Security Rate –100 – False Accept Rate

5 Baseline Performance

6 Existing ID/Authentication SSN/Account# PIN

7 Enrollment SSN/Account# PIN 1-9 KV selection Used by Verifier Optional

8 Verification SSN/Account# 1-9 KV Used by Verifier Optional

9 Summary of design takeaways 1.Maintain consistency between enrollment and verification dialogs 2.Collect enough data during enrollment and verification 3.Use variable length verification 4.Use knowledge verification 5.Use speaker adaptation

10 1.Maintain consistency between enrollment and verification SSN/Account# Authentication 1-9 KV selection SSN/Account# 1-9 KV Only using 1-9 for voiceprint creation and checking Could also use account number, phone number, etc…

11 Choice of Verification Utterance Why use identity claim? –One shorter dialog step –80% of users claim and verify in one step Why use common? –Many users do not like to speak their identity claim in public Identity theft Allow option to touch-tone identity claim –Multiple options for Identification Enrollment very complex and long –Common utterance performance more predictable Out-of-the-box performance better understood ID claim may vary in length –Evaluating performance with identity claim more complex Impostors MUST speak same text as enrollee Identity claim -> Need live impostors

12 2. Collect enough data during enrollment and verification SSN/Account# Authentication 1-9 KV selection SSN/Account# 1-9 KV 3 Enrollment utterances instead of 2: 1-3% lower automation 1 Verification utterance instead of 2: 1-3% lower automation

13 3. Use variable length verification SSN/Account# Authentication 1-9 KV selection SSN/Account# % % Same verification performance as with 2 required utterances

14 4. Use knowledge verification SSN/Account# Authentication 1-9 KV selection SSN/Account# % 10% KV 10% Examples: PIN, Secret Date Verifier not turned on Increases Automation Increases Effectiveness of Adaptation

15 5. Use speaker adaptation SSN/Account# Authentication 1-9 KV selection SSN/Account# 1-9 KV

16 Speaker Verification Performance Speaker Adaptation –Online: Score very well, adapt and get even better –Manual: Unsure, backoff to knowledge, adapt if knowledge passes Cross-channel

17 Thank You!