Abstract: Reverberation characteristics in rooms are currently under question:What should its spectrum look like? How about low frequencies? Could the same frequency characteristics fit both, music and speech? Acousticians are, since long, at odds about these questions! Most standards limit their requirements only down to 125 Hz, may flat below 250 Hz for speech, but with a bass rise for music. This paper concentrates on the understanding that both speech and music containing considerable energy at the lower frequencies. This may excite the eigenresonances of smaller rooms in the form of standing waves and booming modes. In larger halls the superposition of the direct with the early reflected waves may cause destructive interferences when the wave path difference is of the order of a wave length. The resulting muddy sounds are always causing detrimental masking effect on the mid and high frequency sound which defines intelligibility of speech and clarity of music. Damping these interference effects requires the installation of broadband absorbers efficient down to the 63 Hz octave, thus avoiding a bass rise in reverberation if at all possible. A number of existing as well as newly retrofitted halls and rooms in Germany prove the validity of the author´s innovative acoustical layout concept.