Why this lesson matters
You are working on a track and the low end just will not fall into place. On your headphones the kick and bass lock together tightly, but on your speakers it sounds thick and muddy. You walk to the other side of the room and suddenly half the bass is gone. You reach for an EQ, turn some knobs, and it gets worse rather than better. This is not a matter of bad ears or the wrong plugins. It is physics. Low tones have wavelengths of meters, and in a room they behave fundamentally differently from high tones of a few centimeters. Once you understand that mechanism, you look for the solution in the right place: sometimes in the mix, sometimes in the listening position, sometimes in the arrangement. This chapter gives you that foundation, and you will use it in every module that follows.
What you will learn
- Describing sound as pressure variation traveling through air.
- Understanding and calculating frequency, period and wavelength yourself.
- Keeping amplitude and decibel apart, including the difference between dB SPL and dBFS.
- Correctly distinguishing phase, polarity and interference, and recognizing them by ear.
Who this chapter is for
For everyone who produces music or wants to start. You do not need a physics background: everything is built up from the basics, with listening experiments you can carry out in any DAW. Even if you have been producing for a while, this chapter is valuable, because stubborn misconceptions live precisely around phase and decibels.
A preview
One core idea up front. You calculate the wavelength of a tone with λ = c / f: speed of sound divided by frequency. At a speed of sound of 344 meters per second, a bass tone of 100 Hz is therefore 3.44 meters long. Longer than most rooms are tall. A tone of 10 kHz, by contrast, is only 3.44 centimeters. That difference of a factor of one hundred explains why your low end changes per listening position while your hi-hats sound the same everywhere. In the next lessons we work this out into a toolset that lets you hear problems, explain them and fix them deliberately.