Sound absorbing material controls reverberant sound pressure levels within a cavity, enclosure or room. Users of hearing aids frequently report difficulty in understanding speech in reverberant, noisy situations. This instrument, in the church's famously reverberant acoustic, has been celebrated by generations of organists. Shortly after the direct sound, the reverberant sound arrives. Additionally, there are ten instrumented sound-proof booths and a reverberant room. This mechanism becomes especially important in reverberant environments. Summing up these contributions, a reverberant pressure field is created. Weinberg's own experimentation since the "Darkness" days had also led to a more reverberant sound. The source's direct field must be negligible compared to the reverberant field, avoiding privileged propagation. A live concert sounds better in a reverberant than in a dead or dry hall. The design, however, creates reverberant sounds that disturb the experience within the museum. To obtain such conditions, the room must be reverberant. An advantage of DFAT testing over reverberant testing is the portability of the DFAT system.