Composer Sound Attributes

Day 196 Week 29 Q3 Sunday, July 16, 2023

Composer Sound Attributes

Knowing how to think about sound can be extremely helpful for composers. The complex subject of acoustics can be reduced to just three sets of musical attributes, Dynamic, Spectral and Spatial. 

Basically, the dynamic attribute is from loud to soft, the spectral is from high pitches to low pitches, and spatial has to do with directionality as sound is a three-dimensional thing. Almost all music processing falls into addressing one or more of these three attributes. Volume controls and compressors address the dynamic. Equalizers address the spectral. And mono, stereo, surround sound, reverb and delay all address the spatial. When producers and engineers speak of various plugins or dedicated pieces of hardware, they are in general trying to manage or modify these three sets of attributes. You do not have to remember the hundred different names for these processes just know the infinite pile can be reduced to only three categories, dynamic, spectral and spatial. And yes these three all do impact each other.

Now to begin to first drill down into the dynamics as this is the most obvious of the three.

Musical sounds can be extremely dynamic. The dynamic aspect refers to loud and soft. Humans can hear a range from very loud to very soft. This range is about a million to one or 120 decibels. We can hear jet plane engines which are 120 decibels, but from a more musical perspective, humans can encounter music even louder than this in some sound-reinforced concerts where it is not a good idea to stand directly in front of the speakers. We can also hear extremely quiet sounds in an anechoic chamber where there are no reflections. We can hear the random movement of molecules called Brownian motion. This huge is a very, very large range of sound pressure levels.

Historically it was impossible to capture anywhere near this million-to-one range of sounds, which is why compression was developed. From a composer’s perspective, there are a large number of musical operations we can consider to be primarily dynamic processing, from simple volume control all the way to multi-band compressors. When people speak of 16-bit, 24-bit and, very recently, 32-bit audio, they refer to the range of loudness that can be captured and played back. You get 6 dB of dynamic range for each bit. For comparison, over the years, vinyl records could capture a range of about 70 decibels and master tapes were able to get closer to 80 decibels. Still, CDs that are comprised of 16-bit audio theoretically can capture up to 96 decibels. None of these are anywhere close to the range humans can perceive.¬† Digital systems can exceed the dynamic range of human hearing. The current prevalent 24-bit standard can capture 144 dB, which is more than enough. In fact, if you were exposed to a 144 dB sound, it could make your ears bleed. These are all theoretical ranges, and reality permits significantly less to be captured.

There is a very large range of dynamic processes that will be explored at a later time.