How competing speech interferes with speech comprehension in everyday listening situations

Listeners often complain that they have trouble following a conversation when the environment is noisy. The environment could be noisy because of the presence of other unrelated but meaningful conversations, or because of the presence of less meaningful sound sources such as ventilation noise. Both kinds of distracting sound sources produce interference at the auditory periphery (activate similar regions along the basilar membrane), and this kind of interference is called energetic masking. However, in addition to energetic masking, meaningful sound sources, such as competing speech, can and do interfere with the processing of the target speech at more central levels (phonetic and/or semantic), and this kind of interference is often called informational masking. In this article we review what is known about informational masking of speech by competing speech, and the auditory and cognitive factors that determine its severity.