The FIReverb Suite
audio demonstration


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For a feeling of how reverberation/upmix with the The FIReverb Suite actually may sound, this page gives mp3-examples
of stereo to stereo reverb/remix and stereo to 5-channel reverb/upmix from anechoically recorded material, using a binaural
listening simulation. In addition, stereo and 5-channel binaural listening simulation is explained and exemplified so in some
ways it is also a demonstration of CATT-Acoustic auralization.

Skip the explanation/background info, go directly to demonstration.


How the demonstration is made

To be able to present multi-channel replay on a web-page, and over only two channels:
    The multi-channel listening is presented as a binaural simulation. You should imagine what you hear as if you were sitting in a listening room with the speakers surrounding you, like in the figure to the right, and not as if you were listening over headphones to a stereo recording (i.e. you should pretend that the headphones aren't there). The simulated listening room is well designed with appropriate diffusing and absorbing elements and the reverberation times are:
    125
    250
    500
    1k
    2k
    4k
    Hz
    0.40
    0.30
    0.25
    0.25
    0.25
    0.25
    s
    The loudspeakers used have the directivities of a studio monitor. You will hear examples of how each separate speaker sounds.
  • The final binaural files are converted to mp3 using the best encoding setting (giving around 1:5 compression)

  • Both long and short samples are avilable for selection  download times: 35 sec (1.2 MB) or 12 sec (380 kB) per sample.

The anechoically recorded music:
 
  • Performance by the flute/guitar duo Duo Dulce consisting of Mikael Ekholm, flute, and Fredrik Runnström, guitar. Both started their musical studies at the School of Music, Malmö, in 1995.

  • Mikael Ekholm has studied  under Anders Ljungar-Chapelon och Sven-Olof Johansson in Malmö with emphasis on solo and orchestral music playing. He has the past summers given a number of chamber-music concerts in the south of Sweden, mostly in a flute/guitar duo setting but also with piano. Mikael is also about to complete a Master of Science degree with a thesis at the Dept. of Applied Acoustics, Chalmers University of Technology, Gothenburg (topic: comparison between scale- and computer- modeling auralization).
    Fredrik Runnström has studied under professor Göran Söllscher and Gunnar Spjuth. Fredrik performed chamber music in 1997 at the inauguration of Rikskonserter's new venue in Stockholm. During 1997 and 1998 he has also appeared as a chamber music performer in the Swedish National Radio channel 2. He now studies at the Royal Academy of Music in London. 

During the summer of 1999 Duo Dulce gave five
church concert performances in the south of Sweden
with a 50-min program of flute and guitar music.

Web page (in Swedish): Duo Dulce

  • Music played here is a 35 (or 12) sec excerpt from C.P.E. Bach, The Hamburger Sonata.

  • Recording was made by CATT August 1999 in the  anechoic room at the Dept. of Applied
    Acoustics
    , Chalmers University of Technology, Gothenburg, Sweden. At this time the complete
    50-min program was recorded to be used as musical examples for convolution with room responses.

  • Equipment used included:
    • Beyer MCE93 cardioid condenser microphones
    • Art Dual MP tube pre-amplifier
    • Sony PRO DAT PCM-R500 at 44.1 kHz with 20-bit processing

Subsequent processing:


Demonstration

Please note that the samples below must be listened to over headphones! Back to background/info
 
Material Processing Sketch Comment/mp3-file Guidance to "state of mind"
Pink noise Binaural
listening
simulation
A burst of pink noise cycles C L Ls  Rs. 

L = Left
R = Right
C = Center
Ls = Left surround
Rs = Right surround

Download/play:
FIReverb_1_lspsetup.mp3 (short, 148 kB)

I  imagine sitting in my 5-ch listening room, and bursts of pink noise emit from one loudspeaker at a time.
Stereo
flute/guitar
duo
Anechoic
Exactly as recorded.

Download/play:
FIReverb_2_stereo_anechoic_s.mp3 (short, 386 kB)
FIReverb_2_stereo_anechoic_l.mp3 (long, 1106 kB)

I am listening to an anechoic stereo signal via headphones: The sound is very clear but completely inside my head.
Stereo
flute/guitar
duo
Binaural
listening
simulation
How the anechoic stereo recording of the duo sounds when
replayed trough speakers L and R with only the natural
acoustics of the listening room added. 

Download/play:
FIReverb_3_stereo_replay_s.mp3 (short, 386 kB)
FIReverb_3_stereo_replay_l.mp3 (long, 1129 kB)

I imagine sitting in my 5-ch listening room listening to stereo-speaker replay of  an anechoically recorded stereo signal. I must now think that I do no longer listen via head- phones. I notice that it is more relaxing to listen and that the sound is no longer inside my head (1).
Stereo
flute/guitar
duo
Binaural
listening
simulation
How the anechoic stereo recording of the duo sounds after
a stereo remix with reverb as heard over only the left and right
speakers in
the listening room. The two read squares indicate
placement
of two virtual sound sources used for the right and
left
anechoic stereo signals. Note: the amount of reverb is likely
to be too high for many tastes but this is a demo that attempts
to clearly illustrate the principles rather than be subtle.

Download/play:
FIReverb_4_stereo_remix_s.mp3 (short, 383 kB)
FIReverb_4_stereo_remix_l.mp3 (long, 1185 kB)

I imagine sitting in my 5-ch listening room listening to stereo-speaker replay of a stereo recording of the duo playing in a concert hall.
Stereo
flute/guitar
duo
Binaural
listening 
simulation
How the anechoic stereo recording of the duo sounds after
a 5-channel upmix with reverb as heard over the five
speakers in the listening room (2). With a real listening the
difference from the previous example is more obvious. Also
see Note on the previous example.

Download/play:
FIReverb_5_stereo_upmix_s.mp3 (short, 383 kB)
FIReverb_5_stereo_upmix_l.mp3 (long, 1185 kB)

I imagine sitting in my 5-ch listening room listening to 5-speaker replay of a 5-ch recording of the duo playing in a concert hall.
Stereo
flute/guitar
duo
Binaural
listening 
simulation
How only the surround channels of the 5-channel upmix with
reverb sound, as heard over the rear speakers in the listening
room (3).

If the stereo recording already has some reverberation, the
surround filters can be used separately if they in PureVerb
are made to match the hall in question. 

Download/play:
FIReverb_6_stereo_surr_s.mp3 (short, 387 kB)
FIReverb_6_stereo_surr_l.mp3 (long, 1185 kB)

I imagine sitting in my 5-ch listening room listening to only the two surround speakers of a 5-ch recording of the duo playing in a concert hall.
I notice that the surrounds have an obvious "room sound" as created by the rear-facing virtual mics used in PureVerb™.
(1) Unfortunately the binaural simulation hasn't used your own ears (and you are - probably - not using the headphones that are equalized for) but the idea should hopefully be clear anyway. For a real test, download The FIReverb Suite 30 day trial version and try for yourself with real speakers.
(2) The total number of convolutions to create this sample was first 2x5 to create the 5 loudspeaker signals from the stereo duo recording and then 5x2 for a binaural listening simulation (all in all 20 convolutions performed in two steps by the MultiVolver™).
(3) The levels of the surround signals are not exactly as in the full 5-channel replay simulation (example 5).

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