THD vs Frequency Response: Which Spec Matters

Two specs, two different questions

When a headphone listing or a maker page prints a frequency response range or a distortion figure, the two numbers answer different questions. Frequency response describes how the headphone reproduces different parts of the audio spectrum: bass, midrange and treble. Total harmonic distortion (THD) describes how much unwanted harmonic content the driver adds to the original signal.

A buyer deciding between models wants to compare stated details, not guess at unstated performance. The useful comparison is the one the listing actually supports: the tuning the maker claims, and the distortion the maker claims or omits.

What total harmonic distortion means

Total harmonic distortion is a measure of added signal. When a driver reproduces a tone, it can add energy at multiples of that tone's frequency. THD reports that added energy as a small percentage of the total output. A lower printed figure means the driver adds less unwanted content, in the maker's stated terms.

The AirPods Max page at Apple describes a driver motor designed to minimize total harmonic distortion across the entire audible range. That kind of sentence appears on maker pages instead of a number, and it states a design aim rather than a measured specification you can compare across brands.

For a deeper explanation of how distortion is measured and stated, the total harmonic distortion explained article covers the term in detail. A related spec, intermodulation distortion, describes a different kind of added signal and appears on some spec sheets.

What frequency response means

Frequency response describes a headphone's tonal balance. A frequency range figure on a listing states which parts of the spectrum the driver can reproduce, and a frequency response curve on a maker page shows how evenly the headphone treats each band. The curve is the more complete picture because it shows relative levels, not just the outer limits.

Apple describes the AirPods Max driver as producing an extended frequency range that uncovers the rich details of every sound. That phrasing is typical: it states a design aim without claiming a flat response or a specific measured curve.

Reading the curve itself is the subject of the frequency response curve reading article.

Which spec makes a headphone accurate

Accuracy in a headphone means reproducing the recording without adding or removing content. Frequency response and THD address two halves of that goal. A headphone with a smooth response and low distortion comes close to that ideal; a headphone with an uneven response or high distortion moves away from it in different ways.

The two specs are independent. A driver can add almost no distortion yet still color the tonal balance, and a headphone tuned flat can still add audible distortion at some output levels. Listing one spec without the other tells only half of the accuracy story.

That is why the buying guides here compare stated details side by side rather than declare one model more accurate than another. The headphone reviews on this site compare what each listing states: fit, connection, ANC, battery and named audio terms.

What listings and maker pages actually show

A marketplace listing will often print a frequency range in hertz and sometimes a THD percentage, but just as often it prints neither. A missing figure does not mean the headphone lacks a wide range or has high distortion; it means the seller did not state it. The maker's page is the better place to look for the maker's own wording.

Maker pages commonly describe distortion and range in prose. ADAM Audio, for instance, describes its S Series monitors as delivering extended bass response and detailed midrange accuracy with minimal distortion. Apple phrases the AirPods Max driver in the same spirit. Those sentences are claims about design, not comparable numbers.

When a number does appear on a listing, treat it as a stated figure from that seller and compare it with the same figure on another listing with care, because makers measure and report these figures under different conditions.

How to weigh THD and frequency response when you compare

For a casual listener, frequency response describes what you will hear most of the time: the tonal balance. THD matters more when you listen at higher output levels or to material with a wide dynamic range, because distortion grows with output in most drivers.

For a studio or mixing desk, both matter. A flat response helps you judge a mix, and low distortion helps you hear the recording rather than the headphone. The studio monitoring guide and the mixing guide explain what those buyers look for.

If a listing does not state either spec, compare the other stated details: fit, connection, battery, ANC and named codecs. Those are the details the over-ear guide and the wired guide compare across models.

What to pick for your situation

Questions

Which spec matters more, THD or frequency response?

Neither alone decides accuracy. Frequency response describes the tonal balance a maker tuned for; THD describes how much unwanted signal the driver adds. A headphone needs a smooth response and low distortion to reproduce a recording cleanly, but a listing rarely proves either on its own.

Why do some listings not print a THD figure?

Sellers state what they choose to state. A missing THD figure does not mean a headphone has high distortion; it means the seller did not provide the figure. The maker's page may describe distortion in words rather than as a number.

Can I compare THD figures across two brands?

With care. Makers measure and report distortion under different conditions, so a lower printed figure does not guarantee lower audible distortion. Treat printed figures as stated details from each seller, not as a direct ranking.

What should I read on the maker's page if no numbers appear?

Look for phrases that describe the driver and tuning, such as a claim of an extended frequency range or a design aimed at minimizing distortion. Those sentences state design intent, which is the most detailed information the maker offers.

Does a wide frequency range guarantee accuracy?

No. A wide range states which frequencies the driver can reproduce, not how evenly it reproduces them. The response curve, when a maker publishes one, shows the balance across the range, and THD shows how clean the reproduction is.