Tandem Assessment of Spoofing Countermeasures and Automatic Speaker Verification: Fundamentals

TL;DR

This paper introduces new extensions to the tandem detection cost function (t-DCF) for evaluating spoofing countermeasures in automatic speaker verification systems, emphasizing risk-based assessment over traditional metrics.

Contribution

It presents simplified and specialized versions of t-DCF, along with simulation insights and analyses using the ASVspoof 2019 database, to improve spoofing countermeasure evaluation.

Findings

Extended t-DCF with fewer parameters

Insights from simulations on t-DCF interpretation

Analysis using ASVspoof 2019 database

Abstract

Recent years have seen growing efforts to develop spoofing countermeasures (CMs) to protect automatic speaker verification (ASV) systems from being deceived by manipulated or artificial inputs. The reliability of spoofing CMs is typically gauged using the equal error rate (EER) metric. The primitive EER fails to reflect application requirements and the impact of spoofing and CMs upon ASV and its use as a primary metric in traditional ASV research has long been abandoned in favour of risk-based approaches to assessment. This paper presents several new extensions to the tandem detection cost function (t-DCF), a recent risk-based approach to assess the reliability of spoofing CMs deployed in tandem with an ASV system. Extensions include a simplified version of the t-DCF with fewer parameters, an analysis of a special case for a fixed ASV system, simulations which give original insights into its interpretation and new analyses using the ASVspoof 2019 database. It is hoped that adoption of the t-DCF for the CM assessment will help to foster closer collaboration between the anti-spoofing and ASV research communities.