Spatial release from masking stays constant across all SNR criteria tested

Evidence

From this graph it becomes clear that the spatial release from masking remains more or less constant over the complete range of SNR criteria tested. The curves for the separated and collocated curves apparently do not converge. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1658

The mean results are shown in Fig. 2 (bottom), together with the spatial release from masking which equals the difference between the spatially separated and collocated data at each SNR criterion. From this graph it becomes clear that the spatial release from masking remains more or less constant over the complete range of SNR criteria tested. The curves for the separated and collocated curves apparently do not converge. … A two-way repeated-measures ANOVA with factors of spatial condition (collocated or separated) and SNR criterion shows a significant effect of spatial condition [F(1,5) = 125.68, p < 0.001], a significant effect of SNR criterion [F(7,35) = 34.45, p < 0.001], and no significant interaction of spatial condition and SNR criterion [F(7,35) = 1.36, p = 0.253]. The absence of interaction between spatial condition and SNR criterion confirms the constant spatial release from masking that could be observed in Fig. 2 , bottom. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1619

From Fig. 2 it can also be seen that the SNR criterion at which speech intelligibility starts to decrease below the performance in the unfiltered condition (i.e. at SNR = ‑∞) differs among listeners between about ‑4 and 5 dB. … The mean results are shown in Fig. 2 (bottom), together with the spatial release from masking which equals the difference between the spatially separated and collocated data at each SNR criterion. From this graph it becomes clear that the spatial release from masking remains more or less constant over the complete range of SNR criteria tested. … A two-way repeated-measures ANOVA with factors of spatial condition (collocated or separated) and SNR criterion shows a significant effect of spatial condition [F(1,5) = 125.68, p < 0.001], a significant effect of SNR criterion [F(7,35) = 34.45, p < 0.001], and no significant interaction of spatial condition and SNR criterion [F(7,35) = 1.36, p = 0.253]. The absence of interaction between spatial condition and SNR criterion confirms the constant spatial release from masking that could be observed in Fig. 2 , bottom. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1652

Categorization

• QUESTION: Why does spatial release of masking not diminish even at very low SNR criteria? This seems significant and unexplained here.
• XREF: Connects to binaural processing and spatial release from masking discussion elsewhere in the book and general psychoacoustics of hearing-in-noise.
• corroborated: 3 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 1658; Dijk, Pim van, Physiology, Psychoacoustics and…, 1619; Dijk, Pim van, Physiology, Psychoacoustics and…, 1652