Case Study

High-end Showroom Acoustic Re-design

Problem: In this case study of a high-end dealer, the reverberation times were initially too short in the mid and high frequency range, due to an acoustical designer over damping only the front wall, with nearly 2’ of material and many Tectum panels mounted on the side walls. There was no low frequency absorption and no proper absorption of the first order reflections on the walls and ceiling. The walls were a combination of cement block on one side and dry wall on the other. This created a horizontal imbalance of full bandwidth reflections from too much mass on the left and front walls, and not enough support from mass, plus wall cavity resonances on the right wall. In addition, the speaker/listener locations were not optimum for the space, further resulting in non-linear bass response.

Prior acoustic Treatment

Prior treatment removed

FRP before fabric

Finished FRP

Solution: A/V RoomService was hired to make the room the best it could be under some physical constraints. We were able to perform many tests of the room to characterize it before modeling. We removed the existing acoustic treatments, other than some Tectum panels towards the rear of the room. We introduced a double layer of gypsum (furred out from the cement blocks on the left and front walls) with our RoomDamp2 damping compound in-between. This provided some low frequency absorption, reduced cavity resonances and provided horizontal symmetry to the audio scene. We then incorporated our Frequency Response Panel (FRP) system to the front wall, side walls and two areas of the ceiling, further controlling first order reflection points, room modes and reverberation times. In addition, we incorporated our metu CornerTraps in each rear corner. We also optimized the speaker/listener locations for soundstage and room mode interaction. Voicing was included.

Result: Below are the actual before and after treatment reverberation times. As can be seen in the graph below, the room now sounds very natural and articulate due to the FRP system. Note the before and after differences between the acoustically treated room vs. the untreated, as well as the additional improvement with the optimized speaker/listener positions.
·  FRP is effective down to 63 Hz. and is only 2.5” deep
·  Controls room modes, first order reflections, reverberation times and flutter echo in a linear, tunable fashion
·  Conceals with an acoustic stretch fabric system
·  Fitted on-site by professional installers

“I have a guy here [all the way] from Pittsburgh who is also enthralled with the sound he's hearing, as I am I”.

Before and After Reverb Times

Actual Reverb Times

Click to enlarge graph

Reverberation is probably the most recognized characteristic of a room’s sound and the most difficult to control. Reverberation is the acoustic energy in the space that lingers on after the sound stimulus has been removed. Each room’s reverberation times at each frequency are as unique as a signature. Ideally, we want the reverberation times to decay at the same rate across the audible bandwidth, and within a time window of about 0.25 - 0.35 sec. This allows for neutral sound conditions. An exception is for frequencies below about 100 Hz., where we need slightly longer decays in order for our brain to make sense of the difference between what our ears hear vs. what our eyes see. Lack of reverberation control results in masking of low-level details, loss in dynamic range, soundstage, timbre and articulation.