Bass frequencies are always mono because the human ear cannot localize sound below around 200Hz. This means that we cannot tell the direction from which a bass sound is coming.
There are a few reasons for this. First, the human ear has two outer ears, which help us to localize sound. The outer ears are shaped in a way that they diffract sound waves, which creates a phase difference between the sound waves that reach each ear. This phase difference allows us to determine the direction from which a sound is coming.
However, the outer ears are not very effective at diffracting low-frequency sound waves. This is because the wavelength of a sound wave is inversely proportional to its frequency. In other words, low-frequency sound waves have longer wavelengths than high-frequency sound waves. The wavelength of a 200Hz sound wave is about 1.7 meters, which is much larger than the size of the outer ear.
Second, the human head is also an obstacle to sound waves. When a sound wave hits the head, it is reflected and diffracted. This reflection and diffraction can cause the sound wave to arrive at each ear at different times. This time difference, along with the phase difference caused by the outer ears, allows us to localize sound.
However, the head is not very effective at blocking low-frequency sound waves. This is because the wavelength of a sound wave is much longer than the size of the head. As a result, low-frequency sound waves can easily bend around the head and reach both ears at the same time.
Finally, the human brain also plays a role in sound localization. The brain uses the phase difference and time difference between the sound waves that reach each ear to determine the direction from which a sound is coming. However, the brain is not very good at detecting phase differences and time differences below around 200Hz.
As a result of all these factors, the human ear cannot localize sound below around 200Hz. This is why bass frequencies are always mono.
Why is it important to keep bass mono?
There are a few reasons why it is important to keep bass mono. First, it helps to create a more consistent soundstage. When the bass is in stereo, it can create a sense of space and depth. However, this can also make the bass sound less focused and punchy. When the bass is in mono, it is centered in the middle of the soundstage. This creates a more focused and punchy sound.
Second, keeping the bass mono helps to avoid phase cancellation. When a sound wave is out of phase with itself, it can cancel itself out. This can cause the bass to sound weaker or disappear altogether. Keeping the bass mono helps to avoid phase cancellation, which results in a stronger and more consistent bass sound.
Finally, keeping the bass mono is more compatible with different listening environments. When the bass is in stereo, it can sound different on different speakers and headphones. This is because different speakers and headphones have different frequency responses. Keeping the bass mono helps to ensure that the bass sounds consistent on different listening environments.
When to break the rules
There are a few times when it is okay to break the rules and put the bass in stereo. One time is when you are using a subwoofer. Subwoofers are typically designed to reproduce low-frequency sound waves. Because of this, they can be used to create a stereo bass sound that is still focused and punchy.
Another time to break the rules is when you are trying to create a specific effect. For example, you might want to put the bass in stereo to create a sense of space or depth in your mix. Or, you might want to put the bass in stereo to create a more unique and interesting sound.
Ultimately, the decision of whether or not to put the bass in stereo is up to you. If you are unsure, it is always best to err on the side of caution and keep the bass mono. However, if you are feeling creative or experimental, there is no harm in trying putting the bass in stereo. Just be aware of the potential consequences, such as phase cancellation and a less focused bass sound.