sound signature

Understanding Sound Signatures

When searching for a new pair of headphones, a Bluetooth speaker, or a home stereo system there are several factors one needs to consider to make the best purchase decision ultimately. Depending on your intended use, you may focus on waterproofing, Bluetooth range, or price point. However, in most scenarios, sound quality is going to be the key factor in your purchase. This is where understanding sound signatures can become extremely useful.

When you are able to understand how sound signatures work, it will allow you to better understand product reviews where the more technical details of the speaker are covered. It will allow you to select a product that best matches what you’re looking for.

The first and most important concept to understand is how we perceive sound; this is a process known as transduction. Simply put, when a sound is generated, air pressure fluctuations occur. These vibrations are interpreted through a series of components within our ear and converted into electrical signals that our brain can understand as sound.

The air pressure fluctuations are identified as frequencies, of which we can hear the range of around 20Hz to 20kHz. When looking at an audio device’s performance based on technical specifications, the frequency response is incredibly important, as it gives us a basic idea of what frequency bands may or may not be exaggerated or lacking.

For example, a certain speaker might have an emphasis on the bass response and poor high-end clarity, while another may have superb high-end definition but weak bass. These are what we know as sound signatures, and many consumer-grade audio devices adopt one of the below commonly utilized signatures.

Types of Sound Signatures

Flat Frequency Response

Flat frequency response
ExamplesStudio reference monitors, open-back headphones, professional in-ear monitors
Best forCritical listening, recording, mixing & mastering
Works Well WithWhile any music style can be enjoyed on a flat response system, fans of bass-heavy music might find a flat signature to be unexciting.

Sound engineers and audiophiles favor flat frequency responses as they provide the listener with the most accurate representation of the musical content, the way it left the recording studio.

For casual listeners, flat sound signatures may sound boring, as most consumer-grade devices are designed to enhance certain frequency bands. It is worth noting that no device is entirely flat, and our ears also do not operate in a linear fashion when it comes to frequency perception. Flat response devices are often pricier as they are used for more professional applications.

Balanced Sound Signature

Balanced sound signature
ExamplesStudio monitors, audiophile headphones or speakers, PA systems
Best forCritical listening, audio engineering, radio, gaming, TV
Works Well WithAll music genres, spoken word

Balanced sound signatures can be described as a slightly enhanced flat response. Rather than an entirely flat signature, balanced devices feature slight enhancements and cuts in specific frequency bands to deliver a pleasurable listening experience that can be considered relatively accurate to the original source.

U-Curve Sound Signature

U-Curve Sound Signature
ExamplesHi-Fi or home stereo systems, most earphones and headphones
Best forCasual listening, radio, gaming
Works Well WithAll music styles, spoken word

The V-Curve is one of the most popular sound signatures and is based on an emphasis on low-end and high-end, with a slightly scooped midrange. This sound signature enhances the ‘exciting’ content in a piece of music by boosting low-frequency content, providing additional ‘pump’ and warmness to a track, as well as improving the treble region which improves the intelligibility of vocals, and provides an overall warmer tonal signature.

V-Curve Sound Signature

V-Curve Sound Signature
ExamplesCar audio, Bluetooth speakers, many earphones/headphones
Best forCasual listening, radio, gaming
Works Well WithElectronic music, pop, hip-hop, metal

The V-Curve is arguably the most commonly used sound signature, along with the U-Curve. The V-Curve is essentially a more exaggerated version of the U-Curve sound signature. For some, this provides a great enhancement to the overall listening experience, although the sound you’re hearing is considerably different from the original source signal.

Bass Boost

Bass Boost
ExamplesDance-music specialty speakers & headphones, car audio, Bluetooth speakers
Best forCasual listening
Works Well WithElectronic music, hip-hop

A boosted bass sound signature is another of the more commonly-used sound signatures and is often available as an additional feature on many Bluetooth speakers that can be activated or disabled as you please. While a bass boost signature brings the low-end to life and will without a doubt get the dancefloor open, this often results in a serious deterioration of upper midrange and treble clarity.

Treble Boost

Treble Boost
ExamplesSpecialty speakers and earphones, smaller Bluetooth speakers or cheaper devices
Best forSpecialty speakers and earphones, smaller Bluetooth speakers, or cheaper devices
Works Well WithOrchestral, spoken word

A treble boost sound signature ultimately brightens the overall sonic qualities of whatever source signal is being fed through the device. This is not a common signature but can sometimes be found as an additional feature on portable playback systems.

A treble boost signature can be helpful for those hard of hearing, as our perception of the higher frequencies is often the first portion of our hearing range to suffer through age or exposure-related accidents.

Cheaper audio gear can also sometimes be perceived as having a treble boost signature, where, in fact, the speaker lacks the power to represent the low end accurately. The same applies to small speakers that struggle with bass response.

The Harman Curve

Harman International, the parent company behind many well-known brands, including JBL, Lexicon, DBX, and Crown, developed its own sound signature, known as the Harman Curve, in 2010.

The purpose of the Harman Curve signature is ultimately to combine the best features of everyone’s favorite sound signatures, creating a signature that replicates a room full of speakers as closely as possible. From an audio engineer’s perspective, it is clearly based on a U-curve with some additional tweaks along the frequency spectrum, almost a well-balanced point between a Balanced and U-curve signature.

The Harman Curve is implemented in many of their audio products, including household brand JBL. This is what gives JBL speakers that characteristically powerful tonal structure.

Creating Your Own Sound Signature

Many Hi-Fi/Stereo systems, car heads, and Bluetooth speakers allow you to customize the sound signature of the device using either a selection of EQ presets or a fully customizable EQ to craft your own sound to suit your listening preferences best.

The degree to which you can modify your sound signature with EQ will depend on the product. Some products only allow modification on fairly large bands of frequency, while others will offer a more detailed adjustment, where you can adjust each 100Hz or more.

When you’re dealing with Bluetooth speakers, you’re usually quite limited in the EQ control. However, if you’re using a computer, you can easily download impressive EQ software that will allow you to dial in your headphone or speaker sound signatures to an impressive degree.

Just beware that extreme boosting of certain frequency regions can cause a speaker to distort if it can’t handle the frequency content or even blow if overwhelmed. If you want to create your own EQ patch, here are some simple guidelines.

  • To add sub-bass fatness: Boost a little between 16Hz and 60Hz. Depending on the device, you may not have access to this region, and you might not even be able to hear the difference, no matter how much you’re boosting. This frequency region can sometimes not be replicated by certain speakers and is a range that is more often ‘felt’ than heard.
  • For a general bass boost: Most of the bass of a track, depending on the instrumentation providing the low end, will lie between 60Hz and 250Hz. Playing around in this range will add some additional depth to the tonal qualities of your system; just be careful of this frequency range, as a speaker not designed to replicate these frequencies at a high output level will easily distort or burst.
  • For warmth: Look around the 250Hz to 2000Hz range. This region in the frequency spectrum possesses lots of character but should be tweaked wisely.
  • For vocal intelligibility: Much of the vocal character of a performance can be found within this region. However, it should also be used with caution, as too much boosting here can create some strange artifacts in the voice and, depending on the song’s instrumentation, could cause distortions or speaker failure.
  • For improved brightness: Take a look in the 4kHz to 6kHz range. This is where much of the finer details lie, and a small boost here can even make unnoticed instruments come to life. This frequency band also affects the perceived ‘punchiness’ of a track, so use it wisely.
  • For finer details and air: Make some small boosts between 6kHz and 16kHz. While boosting this region can really bring a song to life, too much enhancement here can make musical content come across as harsh and will proceed to cause ear fatigue.

Additional Factors

Aside from the sound signature of an audio system, one must also pay attention to several other elements that influence the sonic performance of an audio device:


The Price of a device often helps us to learn how an audio device might sound. Cheaper units are built from cheaper components, from the driver materials, connectors, and Bluetooth codec to the speaker enclosure construction.

Generally, cheaper systems struggle with the low-end and often have a weak-sounding performance.

Brand or Intended Use of a Device

The Brand or Intended Use of a device will impact your satisfaction with your new audio device.

A flat response system certainly won’t excite a bass-head who listens exclusively to electronic music styles that call for emphasized low-end, in the same way that a jazz listener might not enjoy a heavily bass-boosted speaker system. If you’re buying a device for critical listening, you’ll have better luck looking at pro audio brands over top-of-the-range consumer brands.

Speaker Placement

Speaker Placement is another very important element to consider. For casual listening, you can get away with pretty much anything really. However, if you want to get the most out of your new sound system, it’s worth taking a look at an installation guide to determine speaker height, angles, and listening distance before hooking it up.

Additionally, the surroundings, directionality, and materials the speaker is placed on will affect sound qualities, so consider this, too.

Driver Size

The Driver Size within the speaker greatly affects the sound signature. Larger drivers are designed for low-frequency replication, while higher frequencies are handled by smaller drivers.

A speaker that consists of a series of drivers (a woofer, midrange, and tweeter combo, for example) will sound far ‘better’ than a single-driver unit that’s attempting to produce the entire frequency spectrum. This factor is heavily influenced by your intended listening material.

Speaker Construction

Speaker Construction is yet another important factor to consider, as different materials can be used, all with their own tonal properties that will affect the speaker’s sonic qualities.

The construction of a speaker is another discussion of its own. However, it is important to note the differences between a speaker made from different plastics or woods and how this affects the sound.

Matthew Cox - Author
Written by
Matthew Cox

Matthew is an audio engineering graduate with a strong passion for post-production, recording engineering, and audio technology. Matthew is also an experienced musician with over a decade of experience in recording, touring, and performing. Matthew enjoys studying the inner workings of audio equipment and acoustics theory.

View all articles
Leave a reply