The Ace Challenge 2015

Several established parameters and metrics have been used to characterize the acoustics of a room. The most important are the Direct-To-Reverberant Ratio (DRR), the Reverberation Time (T60) and the reflection coefficient. The acoustic characteristics of a room based on such parameters can be used to predict the quality and intelligibility of speech signals in that room. Recently, several important methods in speech enhancement and speech recognition have been developed that show an increase in performance compared to the predecessors but do require knowledge of one or more fundamental acoustical parameters such as the T60. Traditionally, these parameters have been estimated using carefully measured Acoustic Impulse Responses (AIRs). However, in most applications it is not practical or even possible to measure the acoustic impulse response. Consequently, there is increasing research activity in the estimation of such parameters directly from speech and audio signals.

ACE Challenge Overview

The ACE Challenge was part of the programme of Challenges organised by the IEEE Audio and Acoustic Signal Processing Technical Committee.

The aim of this challenge was to evaluate state-of-the-art algorithms for blind acoustic parameter estimation from speech and to promote the emerging area of research in this field. Participants will evaluate their algorithms for T60 and DRR estimation against the ‘ground truth’ values provided with the data-sets. Furthermore, they are expected to present the results in a paper describing the method used.

Data

A data-set specifically designed for the challenge tasks was provided using anechoic speech convolved with AIRs measured from real rooms with additive noise recorded under the same conditions. This included speech from male and female talkers in different sized rooms and different noise conditions for a single microphone and for microphone arrays with two (laptop), three (mobile), five (cruciform), eight (linear), and thirty-two (spherical) microphones

Task 1

Single-microphone fullband T60 and DRR estimation

Task 2

Multi-microphone fullband T60 and DRR estimation

Task 3

Single-microphone T60 and DRR estimation in 1/3-octave ISO subbands

Task 4

Multi-microphone T60 and DRR estimation in 1/3-octave ISO subbands

Evaluation

The evaluation metrics were to be based on the ground truth values determined using established techniques across a range of dimensions in addition to T60 and DRR such as SNR, talker, and utterance length.