Most of our entertainment is meticulously faked. TV magic doesn’t happen by itself. Go to any live taping on a studio lot and you’ll be prodded to laugh harder, laugh again to a cue, and layered to fill in the gaps for jokes that didn’t land. Talent shows are auto-tuned in post-production so certain performers shine and others sound terribly off-key in their naked state. Just like models are morphed and manipulated in Photoshop to create a hyper-reality, sound is shaped to meet and exceed our expectations. Even those beautiful nature documentaries like Planet Earth are almost entirely fabricated in post-production by some bearded foley artist wearing knee pads in a pit. In nature, a microphone can’t capture quality from a long distance like a camera lens because there’s too much background noise and it disturbs the animals. Things get even stranger when the sounds are swapped. The iconic sound of a bald eagle in movies is usually replaced with the screech of a red tail hawk because the real sound is so small and wimpy. Have you ever heard the sound of a crying rabbit or fox? They are disturbingly human and not what you expect because they aren’t part of your everyday reality.
Expectation and Familiarity:
We form an idea in our head and reality is often much different. Sounds on set are often unusable, and the actual sounds of guns and explosions are too short, thin, loud, and narrow in frequencies to present a convincing illusion. The best sounds often come from unexpected but familiar sources that stimulate the theater of our mind. Bacon is often used for rain, dry ice on sheet metal for groaning spaceships in Transformers, vegetables for punches in action sequences, even the gun in Blade Runner 2045 is made from a synthetic kick drum. Accuracy is not the aim – it’s about providing a convincing illusion that conforms to our expectations, but provides a twist. High-quality familiar sounds combined in unique ways work better than just synthesis or fancy plugin processing. In Mad Max, Mark Mangini combined industrial machines and animals like whales into a convincing hybrid so each vehicle had it’s own unique sound and personality. In Transformers, the Autobots are pitched down 1 semi tone, but the Deceptions are pitched 2-3 semitones to meet our expectation for evil with low pitch. Without that familiar base, the illusion wouldn’t work – it would sit in the uncanny valley. Micro sounds are often used for macro sounds. Most of the giant metal sounds in Transformers were recorded using household appliances like a washer/dryer, rather than dropping junk metal from a forklift.
Reality is incredibly subjective. Our brain takes cognitive shortcuts to fill in the gaps and reduce the work needed to process information for our senses. These shortcuts are so powerful that many species simply go on auto-pilot. Deer will respond to the cry of human baby thinking it’s their own because it falls into a specific frequency range. Pitch it down several octaves and the effect is lost. (Learn more about this on the 20Hz podcast). Whales are even forced to modify their mating calls to higher octaves because of noise pollution competing for the same frequency range. Hearing evolved to provide fast powerful communication, but it had to take some shortcuts along the way. Psychoacoustics gives us several ways to take advantage of these cognitive limits to create more effective music. Let’s explore seven techniques and see how they can apply to your music and sound design.
Waves’ fairly old but groundbreaking MaxxBass technology works by synthesizing higher harmonics to create the perception of a lower bass octave. The brain looks at the pattern of harmonics and fills in the missing fundamental. It’s effective for getting a thicker, fatter mix, or improvements on a single bass track because these synthesized high frequencies take up less bandwidth in the mix. Set the fundamental to the key of your song, drop the original bass a few dB, and add some compression and a limiter to keep things under control. Use in small doses for the best effect. Try R-Bass for the easiest application of MaxxBass. Waves Lo-Air works in the opposite direction, generating a sub-harmonic one octave below the fundamental. This is best suited for effects and sound design. Many consumer devices have MaxxBass technology built in to provide bass presence in small speakers.
Using three rising sine waves at three different octaves, you can achieve an infinite barber pole effect for to build tension, atmosphere, and create seamless transitions. It’s one of the most effective illusions. Automate the volume up on the top note so it increases, keep the volume steady on the middle note, and fade in the volume of the bottom octave. Your ear simply cannot discern where the loop begins and ends because it can only focus on two of the elements pitching up. It’s a great way to extend tension for a long period of time. This can also be used for a downward effect, and also rhythmically with the Risset rhythm – where the rhythm appears to be constantly accelerating.
Both of these techniques are useful for making DJ friendly chromatic transitions from one song to the next when the keys aren’t harmonically matched. A chromatic transition works like a palette cleanser because it sweeps through all the notes rather sticking to a specific scale, which would clash with the incoming song. You can hear great examples of the Shepard tone in Hans Zimmer’s work for Batman The Dark Knight and Dunkirk.
Rule of Two:
Many sound designers try to stick to a maximum rule of one or two loud distinct sounds appearing onscreen at one time. The trick is that these sounds can be placed in a quick series to feel like it’s a stacked complicated sequence of sounds. The main reason for this simplicity rule is that there are so many elements competing for space that elements need to take turns in order to be heard. Dialogue, music, foley, and sound design must all work in concert with each other. One of the most bizarre phenomena is that the rule of two and the rule of three are found in many psychoacoustic techniques. The Shepard tone works because your brain can’t process three independently changing pitches all at once. The same applies for the Tritone paradox, where half octave notes (tritones) are stacked on top of each other in a sequence and it becomes very difficult to discern whether the pitch is going up or down.
Also in the tension category, Infrasonic sound includes frequencies below our threshold for hearing. Sound designers will often inject 19 Hz into movies to add a sense of uneasiness that is felt but not heard. It can be subtle and hard to define, but you definitely notice it. Most likely this is the reptilian part of our brain that is wired for sensing earthquakes and impending danger. Animals like elephants use the 15-30 Hz range to communicate long distances through the ground.
This works by delaying one side of the signal by 1-35ms – just enough so it feels like one cohesive sound. This creates the illusion of width and depth. It’s very easy to create mono-compatibility and phase issues with this, so blend it in at 50% to start. Try it with different sources and see where it’s most effective. I would avoid using it for low-frequency sounds. Manually create the Haas effect by delaying two waveforms, or using a stock delay plugin.
White Noise and Room Tone:
It’s hard to explain exactly what is going on but white noise is great for occupying the brain and creating interest and energy in a song. It fills in all the frequencies and sweetens the drums. Sometimes I’ll add it to a track with some organic noise like vinyl pops or crackling bacon to add some texture to a drum bus, compressing it to glue with the other sounds. Think of noise as the “room tone” for your song, just like sound designers use it as subtle bed to create a convincing environment for a scene. White noise is also great for masking other sounds. It’s likely effective because it simulates a version of natural sounds like crashing waves. Even the simple sound of chirping birds has a calming effect because they signal the absence of a predator or storm.
How do we perceive loudness? Our ears are biased towards the Fletcher-Munson curve – extra sensitive to the 2-5k range. You can create loudness by exaggerating this range with EQ, reshaping the volume envelope of the sound, adding a large reverb tail, sidechaining the reverb to the dry signal, blending multiple mic perspectives and adding harmonics and grit with distortion. Think about the dynamics in the crack of a whip. Create silent moments to add contrast, and use exponential curves or manually ride the volume and capture the automation to add drama. Without quiet, there is no loud. The loudness of a gunshot that can’t be replicated in a theater must be layered, sweetened, and conformed to a certain expectation. The impact of a bullet hits much harder when it punctuates a silent passage.
All of these techniques are ways to suggest emotion and create anticipation. They are not bread and butter techniques for composition. They are slight nudges that play with our cognitive blind spots and steer us towards an emotional destination. Next time you watch a movie, watch how movie composers and sound designers tease in sounds before they are visible in the frame. Listen to how the reverb washes over into the next scene. Feel how the room tone affects the mood. Use these tips tastefully and have fun!
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