Development of a Hi-fi Room pt. 2

Published On: March 31, 2023Tags: , , , , ,

We continue with part 2 of this 3-part series on Listening Room Development. To establish a reference baseline for the following discussion of Hi-fi listening, it is helpful to skim an article published in Stereophile: The View into the Soundstage by John Atkinson

The following is by ASC founder & president Art Noxon, PE Acoustical


Sound Fusion

In addition to the steady state condition, where the sound being heard is 10 dB louder than the sound from the speakers, we have the image shift version of room gain, called the sound fusion or Haas effect. This is where all early reflections that sound just like the direct signal are fused into and become one with the direct signal.

This is not a consequence of room reflections per se, it is a consequence of the reaction time in the process of hearing. Similar to sight, variations in the sound that are heard within the sonic reaction time of 30ms are perceived as one sound. There are dozens of early or primary reflections within the first 30ms following the arrival of the direct signal.

Music Rooms

Some rooms are designed and arranged to support the playing of a particular musical instrument or ensemble in the room. The music room is voiced to support the performance of the instrument. The nature of the flooring, the size and shape of the room, its features, sound diffusing columns, partially draped and partially reflective windows, high coffered and corniced ceilings combine to provide an ambience that compliments the music and the instrument being played.

The music room is “voiced” to compliment the instrument. By this is meant that early reflections are considered and adjusted as they join with and help to define the sound of the instrument. Late reflections, also known as stage shell sound, compete with the direct and early reflections introducing echoes and coloration of the music. Lastly, there is the reverberation, the ambience that seems to fill the room and provide a background glow that is ever changing with the music.

Audiophile Music Rooms

Like an instrumental music room, the HiFi listening room is voiced for the sound producing instruments (the loudspeakers) and type of music being played in the room. Here is where the art of sculpting the enveloping acoustics of the room is introduced. The last link in the audio chain is inescapably the acoustic compliment brought to the music by the listening room.

  1. Speaker position, directivity and off-axis reflection control
  2. Redistribution of early, late, echo and parallel surface paired reflections
  3. Cultivation of reflection density and direction toward enhancing ambience
  4. Development of direction, timing and strength of spaciousness reflections
  5. Room resonance control, minimize speaker/mode coupling and add mode damping
  6. Stage acoustics, controlled reflection development in the front 1/3rd of the listening room
  7. Venue acoustics, controlled reflections development in the back 2/3rds of the listening room

There are 3 levels in the evolution of upgrading the audiophile listening room. These upgrades are developed by judicious placing of TubeTraps along the walls and corners of the room. The TubeTrap is an acoustic product specifically developed for the voicing voice or musical instrument recording and playback rooms–more on this next time.

Thanks for reading, we conclude this 3-part series next week

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