From Seeing it to Experiencing it: Interactive Evaluation of Intersectional Voice Bias in Human-AI Speech Interaction
Organizations: KTH Royal Institute of Technology Stockholm, Sweden · Texas A&M University College Station, USA · University of Edinburgh Edinburgh, UK
Abstract
SpeechLLMs process spoken language directly from audio, but accent and vocal identity cues can lead to biased behaviour. Current bias evaluations often miss how such bias manifests in end-to-end speech interactions and how users experience it. We distinguish quality-of-service disparities (e.g., off-topic or low-effort responses) from content-level bias in coherent outputs, and examine intersectional effects of accent and perceived gender. In this work, we explore a two-part evaluation approach: (1) a controlled test cohort spanning six accents and two gender presentations, analysed with judge-free prompt-response metrics, and (2) an interactive study design using voice conversion to let users experience identical content through different vocal identities. Across two studies (Interactive, N=24; Observational, N=19), we find that voice conversion increases trust and acceptability for benign responses and encourages perspective-taking, while automated analysis in search of quality-of-service disparities, reveals {accent x gender} disparities in alignment and verbosity across SpeechLLMs. These results highlight voice conversion for probing and experiencing intersectional voice bias while our evaluation suite provides richer bias evaluations for spoken conversational AI.
Figures & tables
| ID | Participant Observations on Potentially Concerning AI Response Quality and Bias |
|---|---|
| AI Response Quality | |
| P17 | “[U]sers’ question was reasonably intelligible, even if the AI had difficulty understanding it, it should have probed more deeply, rather than just a ‘say it again in English’ which to someone with an overseas accent can easily be misinterpreted.” |
| P13 | “Seemed very rude that it was asking the user to repeat in English – it could have tried reply what it thought it heard and ask for clarification.” |
| P12 | “AI’s response was way below the standards expected, in fact it bordered on the offensive. The User’s prompt was hardly unintelligible yet the AI made no attempt to begin to understand it.” |
| P23 | “The caller was very clear. I had no problem understanding so for AI to not even recognise the language is extremely insulting, not to mention potential[ly] dangerous if problems cannot be reported” |
| P30 | “…the AI responded with odd information about the application process asking the user to give information about their new address (which they don’t have) and a utility bill at the new address again which they wouldn’t have. This response was not helpful for user at all.” |