The Art & Science of Audio & Video

Haas Effect; (Precedence Effect)

The Haas effect, first discovered in 1946 and named after Helmut Haas, also commonly referred to as the Precedence Effect and/or law of the first wave front. The Haas effect is a psychoacoustic effect having to do with the auditory phenomena that allows us to localize sounds emanating from anywhere around us. This is achieved by using a combination of sensory responses to the varying physical differences between the sounds we hear such as arrival times, level of intensity and phase interactions. Our use of varying arrival times to determine location is a result of simple anatomy. The geometry of the human head with our ears spaced apart and a barrier in between means that direct sound will arrive at the ear closest to the source first and then arrive at the ear furthest away allowing us to locate the source of the sound. Continue reading


July 6, 2008 Posted by | Class: E=MC2(+/-3db) | , , , , , , , , , | Leave a comment

How to properly set delay speakers

When configuring a sound system how do you properly set the delays?

The ultimate goal when setting up delay speakers is for the listener to not even notice the delay speakers are there. Yes, as silly as it sounds it’s true. A properly configured delay will give the illusion that the sound is still coming from the source and not the delay itself. There are several ways to go about a proper setup for your delays. Believe it or not you can actually configure a delay very precisely with a tape measure and not expensive test equipment. Just remember one very simple rule, sound travels 1130 feet per second (at sea level with 70% relative humidity at 72 degrees). In other words sound will travel 1.13 feet every millisecond. So if your delay speaker is 35 feet away from you primary speakers a delay of 31 milliseconds would be right on the money. Of course there are several sophisticated and expensive electronics to do the same thing. They use a calibrated microphone to compare the arrival times of a reference signal from the main speakers and the delay speakers as it arrives at the microphone. This difference in arrival times is obviously your delay time.

However there is also a phenomenon known as the HAAS effect which is too in depth to discuss in one post but what’s important to know is how it relates to settings delay times. In the study of psychoacoustics it is found that often times delaying the “delays” even further behind the arrival time of the primary speakers actually enforces the perception that the sound is originating solely from the primary speakers. This is because the secondary arrival is suppressed due to “involuntary sensory inhibition” which correlates to the human ear’s ability to localize sounds.

by Jason Levert

March 29, 2008 Posted by | Class: E=MC2(+/-3db), FAQ's | , , , , , | Leave a comment

Speaker Cluster Gone Arigh

Q: A year ago we hung two full range cabinets with aircraft cable packed in a cluster above an alter in a church. Since then they have twisted towards stage right just ever so slightly. There is now no way for us to get back up to the ceiling to make any adjustments. What can we do?

A: This is a fun one. Assuming you have some sort of DSP in this system this will be rather easy. If not it will be more complicated. If DSP is available and you are using a separate output for each cabinet you should be able to resolve your problem using delay. If the cabinets have turned towards stage right then delay the cabinet closest to stage left. The interaction of the two cabinets with the delay will steer the image to the left. You simply need to experiment with the amount of delay on the stage left cabinet to re-center the audio image. Now if you do not have DSP available or you are using the same output for both cabinets we will need to get up to the cabinets themselves. Disconnect the rigging cables from the cabinets. By twisting the cables counter clockwise they will have a natural tendency to untwist. This will require quite a bit of trial and error but the tendency of the cables to return to the resting state may be just enough to direct the cabinets front and center once again. Please note that it is very important to not twist the aircraft cable excessively. This will compromise the integrity cable putting undue stress on the individual strands diminishing its’ strength and load capacity. So this solution is to be approached conservatively with your first priority always being safety. Never stray from the standard safety requirements when doing overhead rigging under any circumstances

February 27, 2008 Posted by | Troubleshooting | , , , , , | Leave a comment