Why is flat frequency response so important?

Why is flat frequency response so important?

Frequency response is a way to describe the output of a speaker system. Talking about speaker systems we can look at it as a whole or as individual components. With components reaching across the whole system. They start with the source of the music, continue with converters, amplifiers until the final sound producing speaker. Frequency response of the whole system describes the output of a recorded piece of music by that system.

Information on spec sheets

Most of the time, if at all, there is very simple information on a spec sheet of a speaker system, like frequency range of 20Hz-20.000Hz. This also refers to the range of frequencies a human being might be able to hear. The reference on the spec sheet explains the principle ability of the speaker system to produce tones throughout this whole range of frequencies.

However, a flat response describes a consistent relationship between the amplitude of the source and the amplitude of the speaker system output, from one tone to the other. In other words, if the source contains tones for each frequency from 20Hz-20kHz with the same amplitude, the speaker system would play all those tones with the same amplitude.

If the speaker system by itself accelerates some tones and attenuates others, you would not receive a flat response. This obviously misrepresents the musician’s original intent.

If the frequency response of a speaker system is not flat, the music you are listening to could have some significant sound manipulation, all of which have not been intended by the musician.

Examples of experiences from a not flat frequency response:

  • Basshead- bass-filled music, bass-heavy
  • Punchy- bass is quick to play, does not linger too long
  • Too thumpy- too much impact in the sub-bass regions
  • Muddy/Boomy- bass is too prominent, sticks around too long
  • Bass Bleed- bass is so prominent, overwhelming higher frequencies, vocals will sound muffled, instruments will have an unnatural character, less detailed
  • Recessed- mid-range responses quieter compared to others
  • Sparkle/Grainy- it has a sharp zing to it / it has a rough texture, often due to an elevated treble response
  • Harshness- screechy in their treble response
TestHiFi App, sound test, audio test, hifi test,


TestHiFi App, sound test, audio test, hifi test,


TestHiFi App, sound test, audio test, hifi test,


TestHiFi App, sound test, audio test, hifi test,


The flat response is the universal reference for translating the tonal balance of the musician’s original intent to any sound system and between sound systems. No matter if you are listening to a system in your car or to a system in your living room. A flat response offers a listening experience without coloration when transitioning between audio systems.

There are of course many other influences to the sound you experience. The listening environment, the room acoustics, stereo influences, time coherent alignment of all speakers, distortions and many others.

This does not  mean at all, not to adjust the tonal balance to our preferences. If we like more basshead, we either choose a respective system or a system including adjustment options like an equalizer. However, a system with a frequency response as flat as possible, is capable of playing back the musician’s intent.

Find more explanations on frequency response and sound quality here:

Full video: What is flat response?

More video explanations: HexiBase channel

TestHiFi measures the flatness of frequency response

Therefore, TestHiFi measures the flatness of the frequency response by identifying significant amplitude drops and significant amplitude peaks. TestHiFi’s in-app enhancements provide details on ratings for both, drops and peaks as well as the effected frequency ranges.