There are two aspects to controlling sound in a music practice room: controlling sound within the room and containing sound so that it does not escape to bother others. This paper addresses controlling sound within the room to both make it sound better and to make it easier to contain the sound if this is the ultimate goal. Stopping sound from escaping the room is discussed here. [link]

Controlling sound
Sound molecules - once excited - vibrate in wave-like patterns. These expand outward from the source at an average rate of four times for each doubling of the distance. Once energized, the sound waves will hit walls ceilings and floors reflecting back into the room causing echo, standing waves and fluttering. Controlling the acoustics inside the room is a simple matter of mounting Primacoustic Broadway acoustic panels on the wall surfaces. The more panels you put up, the darker or less ambient the sound will be. How much you put up is really a matter of application and personal taste.

Classical Music
If the practice room is going to be used for a string quartet, you really want to keep the room relatively 'live' as the sound reflecting off the ceiling and walls play an important role in how these beautiful instruments resonate. It is not just the instruments but the combined sound of the instruments and the room that work in symphony to create the sound. This is why so many recordings are performed in old churches; they are very ambient. For classical music, you will likely want to keep the room fairly live and the absorption down to 20% to 25% of your wall coverage.

Big Band Jazz
Sorry all you trumpet players, but it's time to face the truth: trumpets are loud. The sound they make is also very directional due to the frequency and the horn-shape. Trombones and saxophones are just as 'brassy'. When they blast in a room, the reflections off the walls can be very powerful. It therefore makes sense that you will have to increase the percentage of absorption accordingly to between 25% and 35%.

Rock band
Drums, amp stacks and PA systems all add up to loud. This means that you will likely over excite the room which means that mics will border on feedback and acoustic instruments will resonate. This is where you need to consider adding more treatment again - in the around 35% to 50% wall treatment.

Typical room sizes & treatment Classical Jazz Rock
A. 14'x 16' x 9' (ceiling) 150 sq/ft 200 sq/ft 250 sq/ft
B. 16' x 16' x 10' 200sq/ft 250 sq/ft 300 sq/ft
C. 16' x 20 x 14'
D. 20' x 24' x 14'

Now the good news!
The following are some ideas you can apply to save money and simplify your installation. Keep in mind that sound (in the mid and upper frequency ranges) is directional. A bit of good old common sense will help you create a great working space!

1. Treat areas above the waste. Chairs, people, book-shelves, and desks will help absorb and diffuse energy. Save money by treating above the waste!

2. If you have a mixed application - apply the LEDE - live-end dead-end concept to your panel placement and distribute the panels in a 40% - 60% ratio. This will give you a well balanced room with a bit of both!

3. For drums, you should consider adding extra absorption above the drum kit. This can be simple panels or an acoustic cloud like the Primacoustic Stratus or Cloud-9.

4. Use corners to your advantage! When sound reflects off one wall onto the adjacent wall, both the direct and reflected sounds will be absorbed while only treating one surface. Corners are you best acoustic friend!

5. Sparsely distributed panels will create a sense of air while reducing flutter echo and standing waves. So leave air spaces in between panels to get more value from your budget.

6. The impalers used to mount Broadway panels make it easy to mount and relocate panels with very little wall refinishing. Don't be afraid to try different setups. Relax, experiment and have fun!

 

Containing sound in a practice room

Usually, the first step in containing sound is actually to control it. If you can reduce the energy inside the room, your containment scheme will be more effective. This is achieved by placing Broadway absorptive panels on the wall surfaces. Sound energy striking the walls penetrates the absorptive panels causing the minute fibers to vibrate which in turn converts acoustic energy into heat. For a more complete explanation, read 'controlling sound inside a practice room'. [link]

The challenge is trying to contain the sound from escaping the room. Depending on the type of music and volume being played, this can range from relatively easy to practically impossible! Particularly with respect to bass: just stand outside the doors of a nightclub and what do you hear? Bass… traveling right through concrete walls! This is because bass contain significantly more energy than high frequencies and this of course makes it very difficult to contain.

Step-1 Eliminate air passages
The first step in containing sound is to evaluate the air passages. Where air travels; so will sound. If you have ventilation systems that are shared with adjacent rooms, air will pass. Next, examine all o the doors and windows to make sure they are properly shut and are good and heavy. Windows should be double or even triple pane. This is how airport hotels keep air traffic noise out of the rooms. Doors should also be really heavy. Solid wood exterior doors are great. So are old discarded doors that are found in used building supply shops. These often come from schools that change them as they may no longer meet certain fire or safety restrictions. Also make sure that all o the weather stripping is in good order.

Step-2 Add mass to the walls and ceiling
Sound travels through just about anything! Sound travels through air vibrations and will pass through a wall by causing it to vibrate. Adding mass to the wall will make it more difficult to set the wall into vibration. For instance you can double up the sheetrock (gypsum board) to increase the mass of the walls and ceiling. This will definitely help! Doubling the mass can increase the walls ability to attenuate sound by as much as 5dB.

Step-3 Decouple the transmission lines
Sound travels by vibration. A great 'trick' that has been used for years in studio design is to build a room inside a room. Sound vibrations hit the inner wall and set it into vibration. By constructing the outer wall so that it is not connected to the inner wall, it is much more difficult for sound to pass as the energy must not only cause the first wall to vibrate, it must also do the same to the second wall. This is called an offset stud wall. [link]. You can also achieve good results using what is known as resilient channel ort a U shaped metal channel that allows you to build out the wall while leaving an air space in between the two sheets of sheetrock. This is a good option when dealing with an existing wall. [link]. An offset stud wall can increase the attenuation by as much as 25dB and is by far the most effective method of containing sound shot of building a full-blown recording studio.

Step-4 Eliminating the transmission lines
For new construction, you can even go one step further and that is by considering how sound could transmit from one room to another via the beams and joists. Whenever possible build the walls on the same vector (same direction) as the floor joists and this way, sound will not vibrate from one side of the wall through to the other. You can also mount the wall on rubber insulation pads. This way, the sound hitting the wall will not resonate through to the floors. In fact a common solution to stopping sound in recording studios is to build a second floor on top of the first using isolation 'pucks'. This keeps outside noise out and loud sessions in!