Total Harmonic Distortion: What Level Is Audible in Headphones

What total harmonic distortion means

Total harmonic distortion, written THD on audio pages, is a measurement that describes how much extra signal a headphone adds on top of the signal it is meant to play. Imagine a headphone receiving a single pure tone. The headphone should reproduce that tone. Any additional energy it produces at multiples of that tone is harmonic distortion. THD states that added energy as a percentage of the whole output.

A lower stated THD figure describes a headphone that adds less of that unwanted energy. A higher figure describes one that adds more. Those are definitions of the term, not measurements made by this site. The catalogue behind the buying guides states fit, connection, noise cancelling, and battery, and the guides compare what is stated. THD is not among those stated details.

Where a THD figure appears

Most headphone listings do not print a THD number. A title carries the words a shopper reads first: over-ear or on-ear, wireless or wired, noise cancelling, a battery figure. The bullet list may add driver size or Hi-Res support. THD appears more often on a maker's product page, where the engineering story is told.

One maker page states the goal directly. Apple's AirPods Max 2 page says the driver's dual-neodymium ring magnet motor minimizes total harmonic distortion across the entire audible range. That sentence is a design claim from the maker, not a number and not a measurement from this site. The page also names the driver type and the amplifier, which are details a reader can compare against another maker's page.

How to read a stated THD percentage

When a listing or a maker page does state a percentage, read it as a general indication. Lower numbers describe less added distortion, and very small figures are commonly treated in audio descriptions as low. The number is usually measured under one specific condition, at one volume and one frequency, so the same headphone can show a different figure under different conditions. The relationship between THD and other distortion types is covered in a separate article.

Audibility depends on the moment. In a quiet room at a home desk, small amounts of added distortion are easier to notice than they are against train or street noise. That is an everyday description of listening, not a measured claim about any model. The guides on this site compare stated details only, so no article ranks one pair over another on distortion.

Driver types and distortion wording

Headphone pages use driver words: dynamic, planar magnetic, balanced armature. Each names a different way of turning an electrical signal into sound. A dynamic driver uses a voice coil and a magnet. A planar magnetic driver uses a flat diaphragm between magnets. A balanced armature driver is small and common in in-ear designs. The distinction is explained further in the article on driver size and driver type.

Makers of planar headphones often describe distortion in their engineering pages. HIFIMAN's site lists planar headphones across its product families and frames its listening story around them. The relationship between driver type and distortion is part of each maker's design story. A buyer choosing between a dynamic pair and a planar pair can read that story on each maker's page, and can compare the two driver approaches in the article on dynamic and planar magnetic drivers.

What THD wording means for studio, desk, and DJ listening

A listener at a home recording desk or a mixing desk reads the maker's page for the engineering story: the driver type, the earcup back (closed or open), and any mention of distortion. Closed-back listings keep sound in, open-back listings let air through, and each serves a different monitoring habit. Compare closed-back headphones and open-back headphones on stated details.

A commuter or an open-office listener reads the listing for fit, noise cancelling, and battery first. Against train and office noise, small amounts of added distortion are masked by the environment, so the stated figures a shopper can compare are the ones on the title. The noise cancelling guides compare those stated figures.

A DJ reads the maker's page for the driver wording, the swivel earcups that allow single-ear monitoring, and the connection details. Distortion is one engineering word among several on that page. The Pioneer DJ guide compares DJ listings on their stated details.

What to check on the maker's page

When choosing between two pairs, read each maker's page the same way. Look for any mention of distortion, the driver type, the earcup back, and the connection details. A page that names total harmonic distortion is telling a design story; a page that does not may still describe a pair built to play cleanly. The word itself is one detail among many.

The buying guides compare what is stated: fit (over-ear, on-ear, earbuds, open-ear), connection (wireless, wired, or both), active noise cancelling, battery figures, and codec names such as Hi-Res, LDAC, and aptX. Distortion is not one of those stated details, so it stays out of the comparison. For the connection choice, see wired versus wireless headphones.

What to pick for your situation

Questions

Is a lower THD figure always better?

In general terms, yes: a lower stated percentage describes less added distortion. The figure depends on the measurement condition, and most listings do not print one, so it rarely decides a purchase by itself.

Why do so few listings state THD?

A listing title and bullet list carry the details a shopper reads first: fit, connection, noise cancelling, and battery. Distortion is an engineering figure that appears on a maker's product page when that maker wants to tell the design story.

Does THD wording matter more for studio headphones?

A listener checking a mix at a home desk reads the maker's page for the engineering story, because a monitoring pair is meant to show the signal as it is. That is a use case, not a measured statement about any model.

Can you hear distortion during a commute?

Against train, bus, and street noise, small amounts of added distortion are masked by the environment. A commuter reads fit and noise cancelling first, and distortion wording, when present, sits on the maker's page, not the listing.

Do wired and wireless pairs differ in THD?

Wired and wireless describe the connection, not the distortion. Either pair has a driver, and each maker describes its own design. The stated comparison on this site is connection, not distortion. See wired headphones for the comparison.

What does 'minimizes total harmonic distortion' mean on a maker page?

The maker is describing a design goal: the driver is built to add as little distortion as possible. Apple's AirPods Max 2 page uses exactly that wording for its driver.