Two equal interferers plus an 8-dB-lower target yields a global SNR near -11 dB.

Evidence

The relative levels of the three signals were set based on the mean RMS of the two stereo channels after spatialization. The two interfering signals were equalized to the same level, whereas the target speech (before application of the binary mask, see next section) was presented at a level of ‑8 dB relative to each single interferer. This resulted in a global SNR of approximately ‑11 dB. The sound level was set to 62 dB SPL for a single interferer. After signal manipulation as will be described below, the three signals were digitally added which resulted in a total sound level of approximately 65 dB SPL. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1633