Introduction to Music Production 1 – Sound
As a music producer, your medium is sound. Understanding the fundamentals of how sound works is crucial to becoming a professional in the industry.
What is sound?
Sound is produced by continuous and regular vibrations, as opposed to noise (Merriam Webster). How do you make sound? To make sound, you must create vibrations in the air. Consistent vibrations are called oscillations. The frequency (pitch) of a wave depends on the speed of the oscillations. For instance, A4 on a piano is 440Hz. This means the wave cycles (oscillates) 440 times per second. The slower the speed (lower frequency), the lower the pitch. Conversely, the faster the speed (higher frequency), the higher the pitch. The human hearing range is, on average, from 20Hz (20 cycles per second) to 20kHz (20,000 cycles per second).
Another major characteristic of sound is loudness. Loudness (measured as amplitude in dB – Decibel) is a perceived intensity, usually described as volume (also dynamic range). Amplitude is derived from the height of the waves. The higher the amplitude, the more intense a sound will be. The human ear can handle intensity up to 120 dB SPL, also called the threshold of pain. The recommended volume intensity for studios is 85 dB SPL.
There are multiple forms of dB measures, but for actual loudness, dB SPL is used. SPL stands for Sound Pressure Level, and is the local pressure deviation from the ambient atmospheric pressure, caused by a sound wave. When looking at a DAW (Digital Audio Workstation), the values are measured in dB FS (full scale), a relative measure of intensity that does not have an actual, consistent dB SPL measurement. To achieve any level of intensity in dB SPL, you must use some form of amplification (speakers, headphones) and measure the output.
The chart below is called a Fletcher-Munson curve (also called equal loudness curve). It shows the perceived loudness of frequencies in the human hearing range at various dB SPL. Even if two different frequencies are played at the exact same actual dB SPL, the human ear does not perceive them to be equal in intensity. This chart shows the average perception of this. This is important to take note of because in mixing, both in the studio and live, you do not want to make all frequencies the same actual volume, but to use your ears to find the best balance.
How does any of this help my production?
Use your ears! These charts are for basic reference to show how our ears work, not to give you specific numbers to always put every frequency with regard to volume. Only use these to understand why two sounds may appear to have totally different volumes, even if they are set to the same volume. It is a necessity to understand, to a basic degree, how our ears work with regard to amplitude and frequency. We will talk about how frequency and amplitude work in relation to sound design and mixing in later lessons.