Estimating realistic speech levels for virtual acoustic environments

Abstract

Speech intelligibility is commonly assessed in rather unrealistic acoustic environments at negative signal-to-noise ratios (SNRs). As a consequence, the results seem unlikely to reflect the subjects’ experience in the real world. To improve the ecological validity of speech tests, different sound reproduction techniques have been used by researchers to recreate field-recorded acoustic environments in the laboratory. Whereas the real-world sound pressure levels of these environments are usually known, this is not necessarily the case for the level of the target speech (and therefore the SNR). In this study, a two-talker conversation task is used to derive realistic target speech levels for given virtual acoustic environments. The talkers communicate with each other while listening to binaural recordings of the environments using highly open headphones. During the conversation their speech is recorded using close-talk microphones. Conversations between ten pairs of young normal-hearing talkers were recorded in this way in 12 different environments and the corresponding speech levels were derived. In this presentation, the methods are introduced and the derived speech levels are compared to results from the literature as well as from real sound-field recordings. The possibility of using this technique to generate environment-specific speech material with realistic vocal effort is discussed.