Creating
a Stereo Image using Haas Effect in
Your Mix
When we record sounds, creating a stereo image is
very important. A well-made stereo
recording or sound gives us a good localization image of the instruments and
pleasure of music in three-dimensional.
A good quality of stereo imaging comes from the correct recording
techniques of using two microphones.
There are many different recording techniques to create a stereo image,
such as XY, AB, MS, and Blumlein recording.
However, if you failed to record using these proper methods, or you were
only able to record with one microphone and do not have time to rerecord, do
not be worried. There is a tip, which you can create a stereo image during your
mix session. Before we start talking
about the tip, first you have to understand how our human ears perceive sounds.
Duplex Theory of Auditory Localization
Localization of sound in humans is
determined by the interaural time
differences (difference in arrival time) and the intensity differences (difference
in volume) of the same signal by our two ears.
These two principles form a duplex
theory of auditory localization. If
a sound approach from the left side of the listener, it will arrives at the
left ear first followed by the right ear.
In addition, it recognized to be louder in the left ear than the right
ear. Sounds directly from front of a
listener will arrive at both ears at the same time and will recognized as same
intensity in both ears. If two exact
signals come from left and right side in same distance and volume, our brain will
perceives them as coming from center. Our ear is more sensitive to time differences than the intensity differences. In fact, we can perceive time differences
that are small as 0.3 microseconds.
The Haas Effect
Many musicians and engineers think that panning is
a solution for creating a stereo image.
However, panning simply uses the intensity differences of the sounds
that only give you the positioning. It
does not give you the in-depth stereo image and spacious, which make you feel
like you are in the live venue. Therefore,
the key in this game is using the interaural time differences.
When we localize sounds, our brain gives priority to the signal that arrives at our ears first. However, when these sounds are closely together, our brain perceives these sounds as a collective whole, rather than two individual signals. This brain’s perception is called a Haas Effect. This effect is limited to when the reflection signal is delayed less than 35ms from the direct signal. If the delay between two signals is longer than 35ms, our brain perceives them as two individual identical signals.
Let us create a Haas Effect in our mix. For example, there is a mono recorded guitar track and we want to create a stereo image with this single track. In order to create a stereo image using Haas Effect, first we simply take this track and duplicate it. Make the original guitar track hard pan left, and take the duplicated track hard pan right. Then, put a simple delay plug-in on the duplicated track, and slowly increase the amount of delay time on the plug-in while playing back the tracks. You will feel the stereo image is getting wider as you increase the amount of delay time on the duplicated guitar track. Now, we created a Haas Effect in our mix. Theoretically, since these two tracks are identical signals coming from left and right in equal amplitude, our brain should perceives them as coming from center. However, by slightly delaying one track, now our brain is thinking that a stereo signal is coming from left and right in wide range.
If you compare the track that only used a stereo panning and the track that used Haas Effect, you will hear the huge difference in the range of stereo image. However, make sure you do not go pass 35ms, because if you go above 35ms, our brain will perceives these signals as two identical signals coming in with echoes. In addition, you must be aware of using excessive amount of this effect. Using multiple Haas Effects in one mix can cause too wide stereo spectrum, which makes you feel everything apart. Also, just remember that using a Haas Effect is only a technique that can give spices to your mix. The best way to create a stereo image in your mix is recording with correct stereo microphone techniques.
