Informational masking of speech depends on masker spectro-temporal variation but not on its coherence

Abstract

The impact of an extraneous formant on intelligibility is affected by the extent (depth) of variation in its formantfrequency contour. Two experiments explored whether this impact also depends on masker spectro-temporal coherence, using a method ensuring that interference occurred only through informational masking. Targets were monaural three-formant analogues (F1þF2þF3) of natural sentences presented alone or accompanied by a contralateral competitor for F2 (F2C) that listeners must reject to optimize recognition. The standard F2C was created using the inverted F2 frequency contour and constant amplitude. Variants were derived by dividing F2C into abutting segments (100-200 ms, 10-ms rise/fall). Segments were presented either in the correct order (coherent) or in random order (incoherent), introducing abrupt discontinuities into the F2C frequency contour. F2C depth was also manipulated (0%, 50%, or 100%) prior to segmentation, and the frequency contour of each segment either remained timevarying or was set to constant at the geometric mean frequency of that segment. The extent to which F2C lowered keyword scores depended on segment type (frequency-varying vs constant) and depth, but not segment order. This outcome indicates that the impact on intelligibility depends critically on the overall amount of frequency variation in the competitor, but not its spectro-temporal coherence.

Do Age and Linguistic Status Alter the Effect of Sound Source Diffuseness on Speech Recognition in Noise?

“…A number of studies have examined different aspects of auditory scenes to be able to better understand how they may affect speech perception and comprehension. For example, researchers have examined how listening to and processing a speech target is affected by the number of auditory sound sources (e.g., Rosen et al, 2013 ), their intensity (e.g., Dos Santos Sequeira et al, 2010 ), spectral composition (e.g., Li and Fu, 2010 ; Roberts and Summers, 2020 ), and spatial location (e.g., Ezzatian et al, 2010 ; Avivi-Reich et al, 2014 ; Gygi and Shafiro, 2014 ; Bednar and Lalor, 2020 ). These studies contributed to our understanding of how the auditory scene and the acoustic input may affect the ways in which listeners detect, process, and encode acoustic signals and verbal information.…”

“Lass frooby noo!” the interference of song lyrics and meaning on speech intelligibility.

“…The authors estimated that two-third of informational masking is caused by acoustic-phonetic interference and the rest by linguistic interference. Related research has shown that acoustic-phonetic interference depends on frequency variation in the masker, particularly the formant-frequency changes in formant transitions (e.g., Roberts & Summers, 2018, 2020).…”

“…Taken together, the speech-in-speech intelligibility studies reveal conflicting findings regarding which factors are important for separating target speech from background babble. Some studies show clear similarity effects (Brouwer et al, 2012; Roberts & Summers, 2018, 2020; Summers & Roberts, 2020), whereas others show no such effects (Tun et al, 2002), or even opposite effects (Calandruccio et al, 2018). Furthermore, some studies demonstrate familiarity effects (Van Engen, 2010) while others do not (Calandruccio & Zhou, 2014).…”