Binaural summation gives a consistent two-ears vs one-ear benefit

Evidence

Although variability across listeners can also be present, and can range from less than 1 dB to over 10 dB depending on the task and listener, no matter the approach (detection, discrimination, or identification), there is a consistent benefit afforded to the listener who is listening with two ears versus one. Binaural summation does depend strongly on symmetrical hearing between the ears (e.g., Shaw, Newman, & Hirsh, 1947). Even small asymmetries in absolute threshold between the ears reduce the amount of binaural summation observed. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1429

Categorization

• DEFINE: Introduces the concept of binaural summation and its dependence on symmetric hearing.