This blog begins with a simple question - which is more accurate, headphones or loudspeakers? Of course, before we can even begin to answer this question, we must define accuracy. And while we may not have a universally accepted definition, for the purposes of this article the definition for accuracy will be how closely a transducer can replicate the aural information on a recording without altering its harmonic balance, dynamics, or signal-to-noise. Which transducer technology gets us closer to "a straight wire with gain? Before we get to any conclusions, let's look at the primary issues that limit fidelity in loudspeakers and headphones.
The primary issue with loudspeakers is the room they're in. No matter how "good" a room is or how carefully it has been treated, no room is perfect. Every room has issues due to its dimensions, construction materials, and basic specifications. Every dimension introduces its own particular resonance issues, whether they are additive, where room nodes build, or subtractive, where certain frequencies are cancelled or reduced. And then there is floor bounce, where the early reflections coming from the floor reduce imaging specificity. Room gain, which increases low frequency energy is also in intrinsic part of a room's response. Room gain plays an important part in perceived bass, to the point that some headphone manufacturers have incorporated a room-gain EQ curve into their headphones' native response curve. Obviously, a purpose-built room designed from the floor up by an experienced acoustician will be a far better environment than your average living room, but this level of attention requires a lot of time and money to build.
After room issues the next biggest negative influence on accuracy is the dispersion pattern of a loudspeaker and how that interacts with a room. Even loudspeakers that have ruler-flat on-axis frequency response can, as you move off-center, become less even, sometimes to a point that when placed into a real-world room they can sound completely different depending on the amount of side-reflection and absorption in that room. This is especially true of loudspeakers with directional treble and midrange drivers coupled with an omnidirectional bass.
The vast majority of dynamic driver loudspeakers that are housed in a box have an omnidirectional bass response. This often leads to excessive bass build-ups in the corners of untreated rooms. When full range loudspeakers are perfectly centered in a room, it can create a cancellation of bass frequencies at the middle of the room, which is exactly where the listening chair will most likely be located. Untreated rooms and loudspeakers are not ideal playmates.
So, what are the main issues with headphones that limit their accuracy? The first issue is that earphones' high frequency response can't be measured accurately above 8 KHz. This is due to the fact that no two ear canals are identically shaped, and every ear canal has an effect on perceived high-frequency response. A headphone that sounds perfectly ruler flat to me could sound either too dark or too peaky to you.
And then there is how well or unwell an earphone fits. No matter how pristine its frequency response may be, if a headphone is uncomfortable or will not stay in position in your ears or on your head, it will not get much use. Also, if a earphone does not fit properly it will not be delivering the same sound as if it did fit optimally. If an in-ear demands that it be deeply inserted, but you can't achieve that, you will not hear the same results as if it could be inserted optimally.
Unlike rooms, which can be adjusted to better meet the requirements of a particular transducer, your ear canals are not readily adjustable. And while your ear canal's dimensions mean that it is always the same environment for every earphone you wear, the outer environment and ambient noise level can vary from extremely quiet to riotously noisy. Some earphones are designed to reduce outside noise. Many do so by making their enclosures sealed, which introduces issues with the sound trapped inside their enclosures. The early reflections and materials' resonances must be attenuated, or they will reduce fidelity. It's easier to make a harmonically neutral headphone with an open enclosure, but then outside noise can intrude on the experience. Sure, headphones can employ noise-reduction and cancellation circuits, but many of these solutions have their own negative effects on overall fidelity. So, the principal issues with headphones are high frequency response variations, fit issues, and isolation (or lack of it).
With both loudspeakers and headphones, the primary issue that limits their accuracy is not their intrinsic or native performance, but how they interact with the environments they are placed into. And while we can alter and try to improve our listening rooms, there isn't much we can do about our ear canals. So, does that mean loudspeakers can be more accurate than headphones? Not necessarily. And because headphones don't suffer from room interaction issues, are they more correct? Only if their high frequency response curve matches your ear canal shape, they are comfortable, and you are listening in a quiet environment.
Which is more accurate?
If you've read this far, by now you know what the answer is - neither...
Both headphones and loudspeakers face serious issues in the real world that can limit their accuracy. Can these issues be solved? Yes, but not without a lot of time and effort spent looking at the characteristics of both the transducers themselves and their working environments...