Sentinel Hypothesis is a monograph 2xCD album by one of the most important figures of Polish Radio Experimental Studio. Bohdan Mazurek started working in the Studio in 1962 as a recording engineer but soon became its prominent composer, both of illustrative (film music) and autonomous music. His compositions are known for their solicitude for sound and extensive use of traditional instruments - not as neutral or random base for composition but rather as a material presupposing its limitations and ways of usage. The selection of compositions on the album are dated from 1967 to 1989 showing a wide spectrum of his interests from "classical" electronic music to what would today be called field recordings. The CDs are accompanied by thorough analysis of the compositions by one of the most active researched of Studio's history, Boleslaw Blaszczyk, as well as comments of their author, Bohdan Mazurek.