Two Skills Every Audio Engineer Must Develop: Ear Training and Technical Training
Becoming a skilled mixing or mastering engineer requires learning a tremendous amount of information. EQ, compression, signal flow, gain staging, automation, routing, effects, plugins, metering—the technical list can seem endless. But learning the tools is only half of the equation.
For developing engineers, there are really two major areas of training that must progress together: ear training and technical training.
Technical training teaches you how to manipulate sound. Ear training teaches you what needs to be manipulated, why, and by how much. A great engineer has both.
You Can't Address What You Can't Hear
This may be one of the most important concepts for a developing engineer to understand. In fact, most new and many intermediate-level audio engineers not only fail to fully comprehend the critical nature of ear training…they don’t deliberately train their ears specifically for mixing or mastering. Yes, their ears will receive a mediocre level of training by simply listening to music and mixing/mastering music…but this method is random, takes much more time than is necessary, and often fails to develop the critical-listening skills required for professional results.
Your ears are the gateway to creating professional sonic landscapes. Train them and you'll become increasingly capable of recognizing—and creating—the difference between professional and amateur mixes. Neglect them and you won’t know the difference.
There is also an important distinction between hearing and listening critically. Almost anyone with normal hearing can hear the elements of a mix. Critical listening means learning to focus on specific relationships within that sound—level, frequency, dynamics, depth, width, movement, masking, tone and emotion—and accurately determine what those relationships are doing to the music. An engineer doesn't simply hear a mix. An engineer learns how to listen to one.
Imagine that a vocal has an unpleasant resonance around 2.5 kHz. If you can hear the problem but don't yet know how to correct it, that's primarily a technical limitation. You can learn the appropriate EQ techniques and solve it. But what if you don't hear the resonance in the first place? Knowing everything about parametric EQ doesn't help much if you can’t hear when or why you need to apply it.
The same principle applies throughout a mix for any and all mixing parameters. Perhaps the kick and bass are masking one another. Maybe the vocal is slightly too loud. The guitars are consuming too much width. Reverb is pushing an instrument farther back than intended. The mix sounds narrow. Compression is removing the life from a performance. A stereo effect is creating phase problems. The mix has plenty of high frequencies but still doesn't sound open. Instruments are crowded within the stereo field. An effect may just be making something wetter rather than adding depth. The arrangement sections aren’t transitioning properly. Or maybe there are no apparent problems and everything sounds good but some instruments or even the entire mix just needs minor enhancements to push the sound to greatness. If you can’t hear something needing adjusting, you can’t make the adjustments.
An engineer first has to recognize what is happening and why it’s happening. Are there issues that need correcting? Are there things that simply need enhancement? This could be anything from fixing a resonant, annoying frequency that keeps popping up in the lead vocal track to the overall clarity, punch, tone, or dynamics of the entire mix. That's why ear training isn't simply another technical subject to study. It develops the data-gathering system upon which virtually every engineering decision depends.
You can't effectively address what you can't hear.
Learning How Humans Actually Hear Sound
Audio engineering also involves something that meters and analyzers cannot completely explain: human perception.
We don't experience sound simply as numbers. Gain and perceived loudness aren't the same thing. Panning laws affect perceived level as signals move across the stereo field. Fletcher-Munson/equal-loudness relationships help explain why tonal balance can appear different at different playback levels. Phase relationships can reinforce or partially cancel signals. Two speakers can create the illusion of a sound originating from a phantom center where no physical speaker exists. Frequency masking can cause one instrument to seemingly disappear even though its measured level hasn't changed. A short pre-delay can alter our perception of distance. Harmonic content can make a sound seem more present without a large change in measured level.
These principles fall broadly within acoustics and psychoacoustics—the relationship between physical sound and the way our auditory system interprets it. Understanding them technically is valuable. Learning to hear their consequences is even more valuable. For more information on this topic, please read our blog post Psychoacoustics: Why We Don't Always Hear What We Think We Hear.
The Most Important Reference: Knowing What “Professional” Sounds Like
Perhaps one of the hardest listening skills to develop is also one of the most important: Knowing what a professional mix actually sounds like.
Beginning engineers often don't know what they're missing because their internal reference hasn't developed yet. An amateur mix may sound perfectly acceptable to its creator. The drums are audible. The vocals are clear. The guitars sound good. Nothing appears obviously broken. But compare that mix carefully with an excellent commercial production and differences begin to emerge.
The professional mix may have better separation without sounding disconnected. The low end may feel powerful without becoming uncontrolled. The vocal may remain intelligible without simply being louder. The stereo image may feel wider while the center remains solid. Reverbs and delays may create dimension without announcing themselves. Dynamics may be controlled while the performance still breathes.
Perhaps most importantly, everything feels intentional.
Developing that internal reference takes time. Critical listening to great recordings isn't entertainment alone. It's training.
Ask questions:
Where is the vocal sitting relative to the snare?
How much low end is actually present?
How bright is the mix?
Where do the guitars live?
How much ambience can you hear?
What happens to the arrangement when the chorus arrives?
How wide is the mix compared with the verse?
What creates the sense of depth?
The more carefully you listen, the more detailed your internal picture of professional sound becomes. Listening critically to professionally mixed/mastered music is incredibly important to understanding what a good mix actually sounds like. There is one caveat: Try to make sure you're listening in an accurate monitoring environment that doesn't significantly color what you're hearing. For more information on this topic, please read our blog post Sound Advice: Why Your Monitoring Matters.
Technical Training: Learning How to Execute What You Hear
Of course, highly developed ears without technical ability create another problem: You may know something is wrong but have no idea how to fix or enhance it. That's where technical training enters the equation. As an audio engineer, you need to understand signal flow, routing, gain staging, EQ, compression, limiting, saturation, automation, buses, sends and returns, parallel processing, monitoring and metering…and more. In modern music production, this means being proficient in using hardware and/or software tools. It’s critical to understand what these tools actually do and how to use them efficiently.
A compressor isn't simply something you put on a vocal because vocals are “supposed to have compression.” You should understand threshold, ratio, attack, release, knee and gain reduction—and, more importantly, understand how changing those parameters affects the sound. The same is true of EQ. Knowing where frequencies exist is useful. Knowing why you're changing them is much more important. These generalities are valid regarding all the tools used by audio engineers. Plugins and hardware aren't solutions by themselves. They're simply tools used to execute decisions based on determinations made through critical listening.
The Two Skills Feed Each Other
Ear training and technical training aren't separate destinations. They constantly intertwine and reinforce one another. As your ears improve, you begin noticing problems you couldn't hear six months earlier. That forces you to learn new techniques. As your technical knowledge expands, you gain the ability to experiment more precisely. That experimentation teaches your ears what different processing actually sounds like. You hear a problem. You identify it. You choose a tool. You make an adjustment. You listen to the result. Then, you decide whether it actually solved the problem and improved the music to meet your goal as the engineer. If so, great! If not, try an alternate tool and/or methodology until you’re satisfied with the result.
That cycle—listen, identify, act, evaluate—is one of the fundamental processes through which engineers improve. Repeat it hundreds and eventually thousands of times, and decisions that once required considerable thought begin becoming almost instinctive. At higher levels of experience, these skill sets begin to merge. Hearing and acting become increasingly intuitive, allowing the engineer to move beyond simply correcting problems and into the realm of mixing with genuine artistic expression.
Stop Mixing With Your Eyes
Modern audio software provides extraordinary visual information. Spectrum analyzers show frequency content. Compressors display gain reduction. EQs draw beautiful curves. Loudness meters provide precise measurements. Waveforms reveal dynamics and timing. All of these tools are useful. But they can also become a crutch.
A spectrum analyzer can tell you that energy exists at 3 kHz. It cannot tell you whether that energy is emotionally appropriate for the song. A compressor can tell you that you're applying 5 dB of gain reduction. It cannot tell you whether you've just removed the excitement from the performance. An EQ graph can show you a perfectly reasonable curve while the track sounds worse than it did before you touched it.
Meters and visual aids provide information. Your ears make decisions.
It’s perfectly acceptable (and advisable) to use visual tools to support what you're hearing—but not to replace listening. Make mix decisions with your ears and not your eyes. This maxim is vitally important to remember for attaining professional levels of music production.
There Is No Shortcut Around Experience
One of the realities of audio engineering is that both forms of training take time. You can watch hundreds of tutorials. You can buy expensive plugins. You can memorize frequency charts and compression settings. None of those things replaces hours spent listening critically and applying those decisions with your audio tools. Mix songs. Compare them with professional references. Listen on different systems. Come back the next day with fresh ears. Notice what you got wrong. Figure out why.
Then do it again. And again.
Over time, something important begins to happen. You stop simply hearing sound and begin hearing relationships in volume levels, frequencies, dynamics, spatial qualities, energy, tone, clarity, power, movement, and…emotion. Once you can hear those relationships clearly and accurately, the technical tools you've learned become far more powerful.
Train the Engineer, Not Just the Tools
Great engineering isn't about knowing the largest number of plugins or memorizing the most techniques.
It's about developing judgment.
Ear training gives you the ability to make better decisions in the first place. Technical training gives you the ability to execute your decisions. Neglect either side and eventually you'll reach a ceiling. Develop both, consistently and deliberately, and something very different happens: the technology gradually becomes less important than the person operating it. Because ultimately, the most important piece of equipment in any studio isn't sitting in a rack or running inside a computer.
In the end, nothing ultimately matters except what comes out of the speakers. If you can't hear that result accurately and in detail, no amount of technical knowledge can tell you whether you've actually achieved your goal.
It's the combination of trained ears, technical skill, and experienced judgment behind the controls that makes the difference.