The effect of spatial separation in distance on the intelligibility of speech in rooms

J Acoust Soc Am. 2015 Feb;137(2):757-67. doi: 10.1121/1.4906581.

Abstract

The influence of spatial separation in source distance on speech reception thresholds (SRTs) is investigated. In one scenario, the target was presented at 0.5 m distance, and the masker varied from 0.5 m distance up to 10 m. In a second scenario, the masker was presented at 0.5 m distance and the target distance varied. The stimuli were synthesized using convolution with binaural room impulse responses (BRIRs) measured on a dummy head in a reverberant auditorium, and were equalized to compensate for distance-dependent spectral and intensity changes. All sources were simulated directly in front of the listener. SRTs decreased monotonically when the target was at 0.5 m and the speech-masker was moved further away, resulting in a SRT improvement of up to 10 dB. When the speech masker was at 0.5 m and the target was moved away, a large variation across subjects was observed. Neither short-term signal-to-noise ratio (SNR) improvements nor cross-ear glimpsing could account for the observed improvement in intelligibility. However, the effect might be explained by an improvement in the SNR in the modulation domain and a decrease in informational masking. This study demonstrates that distance-related cues can play a significant role when listening in complex environments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Adult
  • Audiometry, Pure-Tone
  • Auditory Threshold
  • Cues*
  • Facility Design and Construction*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Noise / adverse effects*
  • Perceptual Masking*
  • Signal-To-Noise Ratio
  • Sound Localization
  • Speech Intelligibility*
  • Speech Perception*
  • Speech Reception Threshold Test
  • Young Adult