Distortion is the not-so-silent saboteur of loudspeakers. For engineers and product managers, even a few percent of unwanted artifacts can trigger warranty claims, failed compliance tests, or returned products. Before you can specify the right driver—or dial in corrective DSP—you need a clear picture of what distortion is, why it happens, and how each type affects real‑world performance. The sections that follow outline key distortion mechanisms and their practical impact, equipping you to specify drivers that meet performance targets in real‑world applications.
Defining Distortion in Speakers
What Distortion Is Not
Clarifying what distortion is not can make it easier to grasp what it truly is.
Distortion does not simply result from high volume or mechanical strain, nor does it refer to how "loud" or "aggressive" a speaker sounds. A properly engineered speaker can operate at a high output and maintain low distortion. Distortion is also not exclusive to low-cost or consumer-grade speakers. In most well-designed systems, this distortion is minimal and typically inaudible in real-world use.
Additionally, distortion is not the same as the intentional voicing choices often designed into speakers for musical applications. These characteristics, or voicing choices, are tailored frequency responses to emphasize warmth or brightness and enrich the sound produced by a speaker.
What Distortion Is
Speaker distortion is simply any unintended deviation between the input audio signal and the sound the speaker produces. In other words, it's the difference between what a speaker should reproduce and what is actually reproduced.
While there are different types, distortion in speakers is often categorized into linear and nonlinear distortion.
Linear Distortion
Linear distortion refers to the predictable changes in a speaker's frequency response or phase response. This type of distortion doesn't add any new frequencies to a signal; instead, it just alters the balance or timing of the original ones. Linear distortion is often corrected or minimized through design adjustments, tuning, and digital signal processing (DSP).
Bandwidth Distortion
Bandwidth distortion refers to the incomplete or uneven reproduction of a speaker's full intended frequency range. If a speaker's frequency range is 80 Hz to 20 kHz, but begins rolling off at 100 Hz, or has poor high-frequency extension, that's bandwidth distortion. The impact of bandwidth distortion is noticed in the clarity, tonal balance, and the perceived fidelity of the sound. This distortion commonly occurs in small drivers, sealed enclosures, or poor crossover design.
Dynamic Distortion
Dynamic distortion refers to the changes in frequency or phase response depending on the playback level, causing the speaker to behave differently at low versus high volumes. This distortion often occurs in speakers with undersized components or designs not optimized for thermal or mechanical stress, leading to reduced intelligibility or tonal consistency when listening at higher volumes.
Nonlinear Distortion
Nonlinear distortion occurs when a speaker introduces unintended frequencies not present in the original input signal. These distortions are typically more audible and disruptive, especially at higher output levels, and often signal non-ideal behavior in the transducer's mechanical, electrical, or magnetic systems.
Nonlinear behavior typically results from material limitations, suspension or motor asymmetries, thermal compression, or excessive excursion. These cause the speaker's output to deviate unpredictably from the input. The most common manifestations of this are harmonic distortion, intermodulation distortion, and mechanical noise.
Harmonic Distortion
Harmonic distortion occurs when a speaker reproduces integer multiples of the input frequency, known as harmonic overtones. For example, an input signal at 100 Hz may produce additional output at 200 Hz, 300 Hz, and so on. These extra frequencies are not part of the original signal and can color or muddy the sound.
The mechanical components of a speaker, such as the suspension, cone, or voice coil, are often responsible for this type of distortion, especially when pushed beyond their linear range. In well-designed systems, Total Harmonic Distortion (THD) is kept below 2% within the speaker's intended frequency range. THD is a standard metric used to quantify the degree of harmonic distortion, typically expressed as a percentage relative to the original signal.
Intermodulation Distortion
Intermodulation distortion occurs when two or more input frequencies interact, producing new, unintended frequencies, often referred to as sidebands, that are not harmonically related to either input. These artifacts can appear above and below the original frequencies and are usually more noticeable and objectionable than harmonic distortion.
Intermodulation distortion alters both the amplitude and clarity of the original signal and is especially problematic in complex audio signals such as music or speech, where multiple frequencies constantly interact. Unlike harmonic distortion, intermodulation distortion is more challenging to measure, as it requires analyzing how different tones interact simultaneously. Professional-grade tools like Klippel and SoundCheck analyzers are commonly used in transducer engineering to assess intermodulation distortion and optimize driver behavior under real-world signal conditions.
Mechanical Noise
Mechanical noise is a nonlinear distortion originating from physical irregularities or limitations in the speaker's construction. Unlike harmonic or intermodulation distortion, which are byproducts of signal processing within the transducer, mechanical noise is created by unintended vibrations, impacts, or material interactions as the speaker operates, especially at high excursion levels.
Common causes of mechanical noise include:
- Voice coil bottoming out against the back plate
- Spider or surround deformation under high stress
- Loose or poorly bonded components (e.g., dust caps, terminals, glue joints)
- Lead wire slap (the tinsel leads contact the cone or diaphragm)
Mechanical noise can be audible as buzzing, clicking, rattling, or scraping sounds, often appearing intermittently at high volumes or on specific types of program material with strong transients or low-frequency energy.
This type of distortion is particularly problematic because it often occurs as transient mechanical events that aren't visible in standard electrical measurements. It often requires acoustic inspection, laser scanning, or near-field analysis to detect and diagnose. Designers mitigate mechanical noise by using better materials, tighter manufacturing tolerances, robust adhesives, and mechanical safeguards like bump plates or stitched leads to prevent failure under stress.
Distorting Distortion's Reputation
Not all distortion is bad. Guitars rock, in part, because they have a unique "fuzzy" sound which is a form of distortion, and guitar speakers are built specially to handle this. It's impossible to eliminate all speaker or sound system distortion. However, with the right materials, design, and testing, audible distortions can be reduced to the point where they become a non-issue. Understanding the sources and types of distortion allows engineers and system designers to better select or specify speakers for their application—whether the goal is precision, musicality, or durability.
Partner with MISCO for Distortion‑Optimized Loudspeaker Solutions
Mitigating distortion starts with selecting the right transducer. MISCO’s engineering team pairs more than 75 years of OEM loudspeaker experience with advanced test assets—including our on‑site anechoic chamber, Klippel Near‑Field Scanner, and laser vibrometry—to validate every design against stringent performance targets.
Whether you need a fully custom driver, a platform tweaked for your enclosure, or guidance on DSP to keep residual artifacts in check, MISCO can help. Our in‑house prototyping and scalable production lines shorten timelines while ensuring each speaker meets spec.
Ready to improve your product’s sound? Contact MISCO today and discover how distortion‑optimized loudspeakers can elevate your next project.
