The Art of Brightness: Psychoacoustics & High Frequencies
Spinning thrift-store vinyl as a kid, I learned the sound of records before I ever understood what compressors or EQs were. Listening beyond the surface noise and crackle, I heard music that felt balanced. The highs never turned harsh, no matter how bright the record was. I could turn it up, lean in, and still feel comfortable.
Only later did I learn why. Tape absorbed transients and softened the top end. Tubes and transformers added roundness. But vinyl had its own challenge. The cutting head of a lathe could not handle extreme high-frequency spikes on its own, so engineers used high frequency acceleration limiters to control them. That part stood out most because it was a term I had never come across before. Acceleration limiters sounded mysterious, but their purpose was simple.
When a lathe cut a burst of very high frequencies, the cutter head had to oscillate thousands of times per second. At the same time, it was forced to cut deeper into the lacquer for loudness. That rapid motion created heat and friction that could overload the cutter and create distortion on the record. To solve this, transfer engineers, what we now call mastering engineers, developed high-frequency acceleration limiters. These processors reined in sharp bursts without clamping down on lower intensity bursts that may still rise above the threshold. That was part of why those old records felt so easy to listen to. The highs stayed dynamic and alive, but the spikes that could have made them harsh were already under control.
How We Hear High Frequencies
The limitations of vinyl cutting also connected to how our ears are built. Inside the cochlea, sensory hair cells have tiny projections called cilia. The cells tuned for high frequencies sit right at the entrance, which makes them the first to be hit by high frequency transients and the first to wear down over time. That is why hearing loss usually starts with high frequencies fading away.
Sharp spikes of energy, sometimes only a few milliseconds long, can feel piercing because our auditory system treats them as important signals. From an evolutionary perspective, sudden high-frequency bursts were often cues of danger such as snapping branches or the screech of a predator. Our hearing learned to prioritize them, and it still does today. That is why a mix can sound harsh not because it is too bright overall but because those bursts overload the most sensitive part of the ear. Pushed too long, the result is fatigue. In extreme cases, like a jackhammer operator or a sound engineer monitoring too loud, it can lead to permanent damage.
Why High Frequency Transients Cause Problems in Playback
It is not only our ears that struggle with uncontrolled high-frequency bursts. Loudspeakers, tweeters, and even small phone speakers all have to physically reproduce those spikes. A tweeter confronted with a sudden peak at 10 kHz is forced to move back and forth thousands of times per second while also handling the amplitude of the signal. At normal levels most systems manage this well, but at high volumes they can begin to distort. Turn up a track on your phone and you may hear the top end crackle or collapse. That sound is not the mix itself, it is the playback system reaching its limit and saying, “This is too much.”
Mixing With Psychoacoustics in Mind
The engineers of the vinyl era found ways to make records translate and sound musical at the same time. Today the challenge is similar, though often more extreme with the push for brightness and loudness. We want the sparkle that makes a mix exciting without letting it tip into harshness.
Modern tools help but have limits. Resonant suppressors like Soothe can be useful at times, but they often smooth too much and strip away the life and natural dynamics of a sound. At first the effect can feel like ear candy, instantly making a harsh mix sound polished. But over time you notice what is missing, the shimmer, the detail, the natural motion of the high end that makes music feel alive.
Multi-band compressors take a different approach, but they also fall short. They cannot distinguish the small, comfortable transients that bring life to a sound from the big fatiguing spikes that need control. We can adjust attack and ratio, but once a transient crosses the threshold it is treated the same as every other. This often changes too much about the natural detail of the high end. Both tools point to the same dilemma. We want to keep the energy and brightness of the top end while only taming the bursts that cross into harshness.
The Case for Acceleration Limiting
A static EQ cut lowers brightness everywhere. Heavy suppression removes transients and robs the high end of its life. Traditional compression reshapes every transient above the threshold. A responsive process with adaptive attack and release times can instead follow the signal more naturally, leaving high-frequency transients intact when they add energy and stepping in only when they fatigue. This is the core principle behind high-frequency acceleration limiters. Done right, the mix feels more open, more comfortable, and less stressed. Paradoxically, by reducing only the harshest transients, the sound can even feel brighter.
That high-frequency balance, the same one I unknowingly heard on vinyl as a kid, still guides how I approach mixing and mastering today. Kneeling at the turntable, thumbing through records, the cymbals were bright and the tambourines sizzled, but nothing felt brittle. I could turn it up, lean in, and the sound stayed comfortable.
Now, when I mix, I try to create that same balance for listeners on earbuds, laptops, club systems, or cars. Smooth does not mean dull, and bright does not have to mean harsh. The best records keep their shimmer, detail, and excitement, but let you listen for hours without fatigue.
Playback systems handle it better, our ears prefer it, and vinyl engineers figured it out long ago. Control the aggressive spikes that fatigue our ears while preserving the high-frequency transient shapes that give music its vibrancy, and the music breathes.
In my next piece, I’ll take a closer look at how acceleration limiters actually work and why their design still matters today.
Have questions? Comment below, and we’ll get back to you. You can also tag us on instagram—we’re always happy to connect!
Be well,
Ryan Schwabe
Grammy-nominated and multi-platinum mixing & mastering engineer
Founder of Schwabe Digital
