Proper Loudspeaker Placement

Assessing Your Venue’s Acoustic Properties

Acoustically Treated Room

Whether you are giving a presentation in a hotel ballroom or pitching your product at a trade show event, your public address system needs to be set up properly to ensure high quality audio. Loudspeaker placement is extremely important because you want to be sure that your audience hears every word. While each venue has sonic nuances, there are some basic placement guidelines that should be followed no matter the presentation location. But first, let's examine your venue a little more closely.

• One of the first things you will want to consider is the size of the room. Not only should you look at the width and depth, but you should also take note of the ceiling height. Lower ceilings keep the sound closer to the audience while large overhead spaces allow for sound to "get lost" and become inaudible.
• You should also check out the shape of the room. Parallel walls are typically considered by many to be undesirable because the sound does not reflect naturally. This is why most auditoriums, concert halls, and movie theaters feature a trapezoidal shape that is narrower in the front (where the presenter is) and wider in the back (where the audience is). Think about the shape of most loudspeakers. Notice the similarity in shape? That’s no coincidence! Circular rooms are among the worst acoustic spaces, so avoid them if possible.
• Most guest lecturers and brand representatives don't have control over the rooms and venues they speak in; however, if you find yourself in a situation where you do get to choose among several rooms, you can get an edge simply by understanding the acoustic qualities of each room.
• Next, you should look at the type of seating. Are there lots of folding chairs at floor level or is there built-in seating that is positioned in a tiered configuration? Either way, you will want to make sure that your loudspeakers are tilted up or down so the audience is directly in line.
• On a related note, lecturers and presenters should get a count of the audience. This assessment will help you figure out whether a standard two-loudspeaker setup will suffice or if you will need additional sound reinforcement. While most talks, conferences, and trade show presentations have audiences of 50 to 200 people, some applications have many more listeners than that and require more loudspeakers as well as amplifiers.

Properly Setting Up Loudspeakers for Maximum Audio Quality

Now that we've looked into the shapes and sizes of venues as well as the number of people in your audience, let's talk about properly placing your loudspeakers. For the best audio quality, presenters should:

Ideal Placement

• Position the loudspeakers so that the sound from each meets at a shared focal point. "Focal point" is just a fancy way of saying where the sound meets and generally means the back of the room. It is denoted by the oval in the placement diagrams.
• Place each loudspeaker the correct distance from the other. The general rule of thumb is follow a triangular pattern. Some audiophiles argue that an equilateral setup is ideal, meaning the focal point is the same distance from the loudspeakers as the loudspeakers are from each other. Other experts will tell you that an isosceles triangle setup is better. As long as you ensure that the sound from each speaker meets at your intended focal point and the vast majority of the audience is in line with at least one of the speakers, either setup will be just fine.
• Ensure that the entire loudspeaker setup is centered. Positioning the loudspeakers too far to the left or right will result in the sound reaching the focal point at different times. When this happens, the sound waves will actually cancel each other out resulting in either partial or total loss of sound. This principle is called "phase cancellation" and should be avoided at all costs.

No Clear Focal Point Resulting in Loss of Sound

Say "No" to Bleeding Eardrums

Avoiding Feedback

One more consideration to make when setting up a sound system is avoiding feedback from the microphone. Everyone knows that loud squealing sound, and it happens all too frequently at public speaking events. Feedback can be caused by a number of things, but the most common reason is that the microphone is placed in direct line with the loudspeakers of the same system. This creates a feedback loop because the sound source is reamplified again and again. You can avoid feedback by placing your loudspeakers closer to the audience than the microphone. If you have done this but are still experiencing feedback, just reduce the input level of the mike and make sure the loudspeakers are not pointed at excessively reflective surfaces.