What Is Frequency Response and How Does It Affect Your Music?

Samsung Shape M7 frequency response
A frequency response graph for the Samsung Shape M7 speaker. Brent Butterworth

Most any audio product purchased is going to have a frequency response listed as one of the standard specifications. Frequency responses can be found for speakers, headphones, microphones, amplifiers, receivers, CD/DVD/media players. mobile players/devices, and any number of other other audio devices or components. Some manufacturers like to tout having a wider frequency range, yet such numbers tell only part of the story and aren't necessarily an indicator of overall sound quality.

A set of headphones may list a frequency response specification of 20 Hz - 34 kHz +/-3 dB, but what exactly does it mean?

What Is Frequency Response?

A frequency response, which can often be displayed on a graph/chart as a curve, describes how a device responds to sound across a range of frequencies. Frequencies are measured in hertz (Hz) along a graph's x-axis, with sound pressure level (SPL) measured in decibels (dB) along the graph's y-axis. Most products list specifications that cover a minimum 20 Hz (lows) to 20 kHz (highs), which is the generally accepted hearing range for humans. Frequencies above and below those numbers are often referred to as a wideband frequency response and can also be important. The measurement of decibels indicates the maximum variation (think of it like a tolerance or a margin of error) of volume level and how well a device remains uniform from the lowest to the highest tones.

A range of three decibels is fairly common in such frequency response specifications.

Why Frequency Response Is Important

You can take two, non-identical speakers with the same frequency specifications and end up hearing music played differently on each. This is possible because manufacturers sometimes use hardware/software designs that emphasize certain frequency bands over others, not unlike how one can make manual adjustments with a stereo equalizer.

The amount of variation describes how the audio will be affected in terms of accuracy. 

Purists often seek products and components that deliver a neutral (or as close as possible) frequency response. This results in a "flat" sonic signature that uniformly preserves the loudness relationship between the various instruments, voices, and relevant tones without over- or under-emphasizing any particular frequency band(s). Essentially, music can be enjoyed naturally as originally recorded since there is little-to-no forced change to the reproduction. And if one so chooses, further tuning with an equalizer is still an option.

But everyone is entitled to personal preferences, so many speakers, headphones, and various components offer their own unique take on things. For example, a "v-shaped" sound signature boosts the low and high frequencies while recessing the mid-range. This can appeal to those who listen to EDM, pop, or hip-hop music genres (to name a few) that express a lot of bass and sparkly treble. A "u-shaped" sound signature is similar in shape, but with frequencies adjusted to a far lesser degree.

Some products go for a more "analytical" sound that boosts the highs (and sometimes the mid-range) while recessing the lows.

This can be ideal for those who find themselves listening to classical or folk music genres, among others. A set of "bassy" headphones or speakers will boost the lows while recessing the highs and mid-range. Sometimes a product exhibit a sound signature that is a hybrid of one or more types.

The overall frequency response helps – but isn't the only element – to determine how sound is perceived with respect to separation of instruments and detail of individual elements. Products that exhibit sharp dips or spikes in frequencies can lead to listening strain or fatigue. The speed at which notes play and linger (often characterized as attack and decay) also makes a significant impact on the experience.

Product types are equally important, since headphones and speakers with same/similar frequency responses can still sound different due to the space required in order for each to express.