Speaker Placement and Other Mysteries of the Universe
July 11, 2007
I’m sure you’ve noticed in the studio that the engineer sits in the sweet spot which is centered between the monitors. Whether it a stereo or surround mix, there will only be one point in the room that is ideal for listening in the most balanced and clear manner. In a live situation, the only spot that might be considered ideal is the front-of-house mixer’s position, since it is usually centered between the two speaker arrays. As musicians on stage, unless we’re wearing in-ear monitors, we find that there are certain areas on stage where we can hear some things better than others.
So what can we do to make bigger sweet spots on stage and for the audience in a live setting? The first thing to do is agree on some established basics, then build from there.
Try this interactive demonstration: take one hand and move your fingers together as if you were going to snap them – do it just hard enough to hear your fingers rubbing against each other, but not hard enough to snap. Then close your eyes and put your hand out in front of your face at eye level and begin moving your fingers in that almost-snapping motion. Assuming you have balanced hearing, you should perceive the sound as coming from directly in front of you. Continue to rub you fingers together, again with your eyes closed, and slowly bring your hand around to one side of your head, then return to the center, and over to the other side. Then try it behind your head, above your head, down in front of you, and finally down beside you. Do you notice how the clarity of the sound changes in relation to the location of your hand? It won’t take much to realize that the sound is clearest when your fingers are directly to the side of either ear. The least amount of perception, or greatest rejection of sound, is directly behind and below you. This would be a good time to think about where your amp is located while playing.
Take a minute and think about how this hearing pattern might have an impact in different musical situations, such as amp and monitor placement. Now make note of the following information, and later we’ll work on putting it all together to begin solving problems.
It takes the least amount of energy for a sound to be heard when it can enter directly into your ear canal from its source. When somebody tells you a secret, they whisper in your ear, not to your forehead. Think of it like the warning sign on the back a semi that says, “If you can’t see my mirrors, I can’t see you.” A speaker’s warning sign should say, “If your ear drum can’t see my cone directly, you aren’t hearing me ideally.” Lower frequencies need more energy to be heard than higher frequencies, and from about 125 Hz down, sound is considered omni-directional, making the location of the source less critical. This is why subs can be put out of sight and not lose any effectiveness. Low frequencies also need more distance to develop and be heard because their wave lengths are longer, which allows the sound to literally bend in direction without losing it’s quality as quickly as high end frequencies. Midrange frequencies, located from 1.2 kHz - 1.4 kHz, are in the same range as the human voice. They are perceived easily and need less volume than bass frequencies to be heard clearly. However, as those midrange and high frequencies get further off axis in relation to your ear, they become less clear.
It is generally accepted that the human ear hears the best balance of frequencies at about 85dB. Our ability to distinguish sound clearly is affected by both the volume of sound entering our ear as well as the actual frequencies of the different notes. Another factor in hearing clearly is Frequency Masking, which is when a sound covers up – or masks – another sound because it’s either louder, closer, or covers more frequencies than the original. For example, studios have a flashing light attached to their telephone for when the music from the monitors masks the ringing of the phone. We’ll cover this in more depth in next month.
Until next time, your mission – if you choose to accept it – is to draw a stage plot of the last time you played showing the location of all of the amps, monitors, etc. Then, using the information above, draw another stage plot showing a layout that you think would help everyone hear better. Don’t forget to take the audience and location of the P.A. speakers into consideration. Everyone wants to be heard, and everyone can be, if we all play by the rules of sound and the laws of physics.
Creation Audio Labs, Inc.