Figure 1. Skyline® ceiling and DiffusorBlox® wall installed in an individual practice room at CIM.

Individual practice rooms play an essential role in music education. It is here that a music student gets to “sing in the shower”, minimize the causes of unwanted sweaks and buzzes, develop articulation, technique, intonation, tone production and develop the individual style that is performed on stage. For all the good that practice rooms do, and the extensive hours students spend in them, they are very acoustically impoverished, uninviting and uninspiring cubicles. Their usefulness can be compromized by poor room acoustics. They usually are small rectangular rooms, 8 to 25m3, fabricated from concrete block, with commercial acoustic ceiling tile, some variable curtain, concrete floors and a full length mirror, which students use to monitor their posture and fingering. In other words, a low-cost functional student-proof space. Since the surfaces are usually concrete and the volume is small, the rooms typically have audible modal frequency problems and poor sound diffusion. Another approach used is a prefabricated isolation cubicle. These rooms are typically small, but often have purely absorptive surface treatment, making the space relatively dead.

Consider a candidate room which was 4.5m long, 2.1m wide on one end, 2.4m wide on the other and was 2.7m high. The room had a conventional compressed acoustical ceiling glued to drywall, concrete floor, cinder block walls and a thin variable curtain. As part of a student special study activity at the Cleveland Institute of Music, a series of objective measurements and subjective musician impressions were recorded before and after acoustical changes.

Thesis
An individual practice room that offers music education students the simultaneous ability to clearly evaluate articulation and intonation can economically be designed using DiffusorBlox® walls for modal and volume control, structure, and 1D diffusion, with Skyline® ceiling treatment to improve sound diffusion.

Figure 2. Length axial modes are attenuated with DiffusorBlox®

Conclusion The experiments verified that with the introduction of modal control, horizontal and omnidirectional diffusion, a very functional and enjoyable practice room could be attained at relatively low cost. The specific conclusions were as follows:

1. Modal Control: The use of DiffusorBlox® on only one wall surface provided significant low frequency modal control. This is seen in the room response plotted with and without DiffusorBlox®. Figure 2 illustrates how the introduction of DiffusorBlox® reduced the axial modal resonances in the 4.5m direction at 76, 114, 152 Hz, etc. The significant decrease in low frequency reverberation time can be seen in Figure 3. It also allows the musicians to move closer to the walls, without experiencing exaggerated bass buildup.

   
   Figure 3. DiffusorBlox reduce low frequency reverberation time and bass buildup

2. Ambiance: The use of 1D wall diffusion and 2D ceiling diffusion simultaneiously provides reflection control and ambiance with envelopment. Good sound diffusion also lessens practice fatique.

Figure 4.
Top: Time response with backward integration envelope for untreated room. C50 = 4.67 dB.
Bottom: Time response with backward integration envelope for practice room with acoustic treatment. C50 = 6.50 dB. (Note dense uniform decay.)

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