Acoustics - Making a Good Practice Hall

This article is especially intended for beginner bands, but maybe some seasoned pros can pick up a few tips here and find an explanation for some reocurring problem in the practice hall that you just couldn't put your finger on.

Sound is a very 'naughty creature' and is entirely at the mercy of the acoustics of the environment where it's produced. Let's take a look at the most typical practice hall: the good ol' garage or tool shed. Take a look at the walls, floor and ceiling first. What materials were used to construct it? Are they hard flat surfaces? If so, you're going to feel like you're playing in a tiled bathroom. Yeah, lots of reverb, boomey bass and irritating highs -a nightmare for playing anything but chamber music or soft balads with little or no drums! Reverb makes vocals sound good -maybe that's why people love to sing in the shower! But this same reverb is no good for fundamental instruments like the bass and bass drum because the sound reflects and reflects off the walls causing uninteligibility and chaotic sound.

So, what can you do to make it sound more like a good practice hall?

First, let's look at how sound behaves. Low frequencies go out in all directions, and as you move up the frequency spectrum, you'll find that these frequencies become more and more directional. If you want to experiment what I'm saying, take a hi-fi speaker and place it outdoors where you're sure the sound won't reflect off of any wall nearby. Play your favourite music and stand in front of the speaker. If you're standing about five or six feet in front of it, you'll probably hear everything perfectly. as you slowly move around to the back of the speaker, you'll notice that the first thing that disappears is the high frequencies, then the high mids, then the low mids. When your behind the speaker, you'll notice that the only thing you can hear are the low frequencies, right?

Now place yourself in front of the speaker again, but this time get up close to it. Start walking backwards slowly in a straight line. You'll notice that the first frequencies to go are the lows, then the low mids, high mids and finally you're left with the highs.

What did you learn from all this? That's right! Low frequencies make a spherical pattern around their source, while high frequencies are very directional. And THAT'S the problem. Sound naturally behaves like this and we've got to work with it because we're musicians.

High frequencies can be easily absorbed by putting carpeting on the walls. Thicker, softer materials like fiberglass wool covered with cloth and stapled to the wall does wonders for your sound. You'll feel like you're playing in a recording studio! But here we might be killing the sound. You can try making a few panels like this (on the ceiling too) and using wood for the spaces in between because wood has a very musical sound to it -what are most instruments made of? Finding just the right balance of fiberglass wool and wood depends on how you want the room to sound like so experiment systematically. Maybe one panel on each wall and the ceiling to start and try it, etc.

Low frequencies are harder to control. The bass player needs to know how to equalize his sound to 'clean up' the working environment. In my article 'Why Blame the Bass Player', the bass player's job concerning sound is explained in a practical manner.

If you're trying to avoid sound getting out of the practice hall and into your neighbour's ears, you've got some more work to do. Ideally, what you want to design is a floating room inside the room. The floor is the most portant part to deal with. In the area where you set up all your instruments and amplifiers, throw about 3" thick upholstering foam or any spongy material evenly on the floor then cover it with a wood structure (you're designing a low stage for your practice hall), but don't let this structure touch the floor or the walls directly (it must be floating). If it lacks stability, you can use rubber spacers under the corners and in the middle. If you're hanging speakers from the roof, use bungy rope or something like that to hang them so they're 'floating' and not transmitting vibrations to the structure of the building and make sure all amplifier speakers are sitting on the 'stage'.

If all has been done well, you will have considerably reduced the thumping that gets out of the practice hall that makes the plates in your neighbour's house vibrate. If necessary, repeat the floor process and make a smaller platform on top of the stage to set the drums and amplifier speakers on -especially the bass amp.

Next, look for cracks and holes where sound can get out. Windows and doors should be doubled and ideally, though much more expensive, make an inside wall and ceiling and put fibreglass wool between the two. Or how about this... Do you really need your whole garage to practice? Probably not. So you can make a room just for practicing with a door and walls and a ceiling that are not making direct contact with the other walls the floor or the ceiling in your garage or shed (a room inside a room). That just saved us some money, didn't it? Your neighbours will definitely be grateful to you and you won't be talking to Mr policeman so often.

Speaker placement is another important factor. If your guitar amp is on the floor and facing to the front, don't expect to hear it well; your legs don't have ears! Either place it on a small table or place it monitor style on the floor so you get the sound directly and believe me, you won't want to turn it up so loud! Also, to listen to your amp properly get at least five feet away from it so you can hear the other musicians and find the right mix.

Oh and one last thing. If you control the sound inside the practice hall, you'll find that everything sounds good and there's no need to turn everything up so loud.