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What is Frequency Response? (2024)

Frequency response is a concept that you’re definitely familiar with if you’ve spent enough time around audio professionals. It can come up in just about any conversation, from those about headphones and speakers all the way up to those about DACs and amplifiers, as well as those about room acoustics. Here is everything you need to know about frequency response, regardless of your level of familiarity with the topic or your knowledge of the phrase.

We are dealing with frequency, as the name implies, and how well a specific component can reproduce all of the tones that we can hear. Human hearing can distinguish between very low frequencies, which start at just 20 Hz, and very high frequencies, which start at about 20 kHz. Even so, each person’s hearing will fall somewhere between these two extremes. This is frequently divided into bass, medium, and treble sections in terms of music. Although these aren’t exact definitions, generally speaking, bass is defined as frequencies between 20 and 300 Hz, mid is 300 Hz to 4 kHz, and treble is anything beyond 4 kHz.

Frequency response evaluates whether and how well an audio component reproduces each of these audible frequencies as well as whether it modifies the signal along the way. What is the lowest frequency that subwoofer X can reproduce, for instance. The optimal frequency output of a component should be equal to the input, excluding any intentional EQ adjustments, in order to preserve the signal. A set volume sine wave (measured in decibels) can be swept through the system and will have the same amplitude at all frequencies at the output. This is frequently referred to as a “flat” frequency response.

In other words, the best frequency response doesn’t alter the volume of the source’s bass, middle, or treble. In contrast, if you’ve played about with the EQ settings in any music software, you may have noticed a non-flat EQ setting that increases bass or lowers treble, etc. As a result, you might hear more or less of a given frequency than there was in the original signal if a component (such a headphone driver) doesn’t have a flat frequency response. In some circumstances, this can make listening unpleasant.

Why is Frequency Response important?

It is the ability of an audio device to play all low, middle, and high tones accurately—and in the right ratio to one another—that allows our ears to determine whether or not it is a high-fidelity unit with rich, lively sound.

Remember that the decibel, or dB, is a unit of measurement used to represent how loud a sound is. The capitalization of the “B” honors Alexander Graham Bell and his contributions to acoustics. I’m not kidding. Then, for a certain range of frequencies, we state how many decibels (dB) the equipment deviates from optimal performance. The smallest variation in sound pressure level (SPL) that can be reliably heard by someone is typically regarded to be 1dB. A change in volume of 3dB is noticeable but still quite faint. Since the dB scale is logarithmic rather than linear, 10dB louder is considered to be “twice as loud.”

For instance, a speaker or headphone may be stated to have a frequency response if the range is 40Hz–20kHz and the variance is 3dB. “Danger, Will Robinson!” should sound if a manufacturer provides a frequency response without a xdB fluctuation. No dB variation was specified, hence nothing was measured. Simply stating “20-20kHz” has no meaning whatsoever, and it casts doubt on the veracity and integrity of everything else the manufacturer claims.

There are two types of audio frequency response curves: flat and curved. In the designs of microphones and speakers, both curve kinds are present. Digital signal processing (DSP)-based adjustable curves have been integrating into consumer theater systems for a while. Although the design does not have an unique curve, technology has advanced over the past fifty years, making it worth taking into account.

How does my work change as a result of a tailored frequency response? These are both excellent inquiries. Whichever responses are provided should improve the user experience.

A microphone’s design and electrical component choice result in the precise form of its response. This explains in large part why different microphones have varying timbral qualities, as well as how they can lend texture and color to recordings.