The effects of reverberation on a listener's ability to recognize target sentences in the presence of up to three synchronized masking sentences

Abstract

Objective: To determine the effects of room reverberation on target sentence recognition in the presence of 0-to-3 synchronous masking sentences. Design: Target and masker sentences were presented through four loudspeakers (±90° and ±45° azimuth; 1m from the listener) in rooms having reverberation times (RT) of 0.2, 0.4, 0.6, and 1.1 s. Study Sample: Four groups of 13 listeners each participated in the study (N = 52). Results: In rooms with RTs of 0.2, 0.4, and 0.6 s, mean speech recognition scores (SRSs) were similar, with scores ranging from 96–100%, 90–95%, 75–80%, and 53–60%, when 0, 1, 2, and 3 competing sentences were present, respectively. However, in the room with a RT = 1.1 s, SRSs deteriorated significantly faster as the number of competing sentences increased; mean scores were 93%, 73%, 26%, and 10%, in the 0, 1, 2, 3, competing sentence condition, respectively. The majority of errors in SRSs (98%) resulted from listeners reporting words presented in masking sentences along with those in target sentences (mixing errors). Conclusions: Results indicate that reverberation has a similar influence on SRSs measured in multi-talker environments, when room reverberation is ≤ 0.6 s. However, SRSs are dramatically reduced in the room with a RT = 1.1 s, even when only one competing talker is present.

Sumario

Objetivo: Determinar los efectos de la reverberación de un cuarto para el reconocimiento de oraciones blanco, en presencia sincrónica de 0–3 oraciones enmascarantes. Diseño: Las oraciones blanco y las enmascarantes se presentaron por medio de cuatro altoparlantes (+90° y ±45° azimuth; a 1m del oyente) en cuartos que tenían tiempos de reverberación (RT) de 0.2, 0.4, 0.6 y 1.1 seg. Muestra de estudio: Participaron en este estudio, cuatro grupos de 13 oyentes cada uno (N=52). Resultados: En cuartos con RT de 0.2, 0.4 y 0.6 seg, las puntuaciones medias de reconocimiento del habla (SRS) fueron similares, con puntuaciones que variaron de 96–100%, 90–95%, 75–80%, y 53–60%, cuando se presentaron, respectivamente, 0, 1, 2, y 3 oraciones competitivas. Sin embargo, en el cuarto con RT=1.1 seg, las SRS se deterioraron significativamente más rápido, conforme el número de frases competitivas se incrementó; las puntuaciones medias fueron de 93%, 73%, 26%, y 10%, en las condiciones de 0, 1, 2 y 3 oraciones competitivas, respectivamente. La mayoría de los errores en las SRS (98%) resultaron de oyentes que reportaron palabras presentes en las oraciones enmascarantes junto con aquellas de las oraciones blanco. (mezcla de errores). Conclusiones: Los resultados indican que la reverberación tiene una influencia similar en las SRS, medidas en ambientes de hablantes múltiples, cuando la reverberación es ≦0.6 sec. Sin embargo, las SRS se reducen dramáticamente en un cuarto con un RT=1.1 seg, incluso cuando solamente está presente un mensaje competitivo.

Key Words::

• Speech recognition
• Cocktail party effect
• Reverberation

Acknowledgements

The authors would like to thank Mr. Tuyen Tran for designing the initial version of the custom software used in conjunction with the S³ corpus. This work was supported by the U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland, USA.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper