Reverberation

The reverberation measure , also direct sound - reverberation level distance , is the logarithmic ratio of the sound energy of the direct sound to the total reflected sound energy (hall energy) that is present at a point of interest in an interior room (e.g. at a certain listening location in a concert hall ): ${\displaystyle H}$

${\displaystyle {\begin{aligned}H&=10\cdot \lg {\frac {E_{dir}}{E_{refl}}}=L_{E_{dir}}-L_{E_{refl}}\\&=20\cdot \lg {\frac {p_{dir}}{p_{refl}}}\end{aligned}}}$

It means:

• H = reverberation level in decibels  (dB)
• E _dir = energy of direct sound
• E _refl = energy of the room sound
• L _E = sound energy level in dB
• p _dir = sound pressure of the direct sound
• p _refl = sound pressure of the room sound

The reverberation level can be used to assess the audibility of a listener in an auditorium . However, other criteria also contribute to the clarity and transparency of a sound event.

According to investigations by Walter Reichardt and W. Schmidt, 15 levels of room impression can be distinguished from direct sound and room sound ( reverberation ):

Reverberation part predominantly									Direct sound component predominantly
H	<−23 dB	−17.5 dB	−13 dB	−9.5 dB	−6.5 dB	−4 dB	−2 dB	0 dB	2 dB	4 dB	6.5 dB	9 dB	12 dB	16 dB	> 22 dB
step	−7	−6	−5	−4	−3	−2	−1	0	1	2	3	4th	5	6th	7th

With a reverberation level of 0 dB, the reverberation distance is available.

literature

• Walter Reichardt u. a .: Definition and measurement basis of an “effective reverberation distance” as a measure of the spatial impression in music performances . In: Journal for electrical information and energy technology , Jg. 4, 1974, p. 225, ISSN  0046-8398 .
• Michael M. Rieländer (Ed.): Reallexikon der Akustik . Erwin Bochinsky publishing house, Frankfurt / M. 1982, ISBN 3-920112-84-9 .
• Wolfgang Schmidt, Walter Reichardt: Room acoustic criteria for language and music . In: Taschenbuch Akustik , Volume 2. Verlag Technik, Berlin 1984, p. 1199

The “ reverberant energy level” (Reichardt) found in the literature is now referred to as the reverberant energy level .