Audio Basics: Frequency Response

We’re excited to announce the launch of a brand new instructional series Audio Basics. In this series we walk you through the key measurements used to characterize audio transducers, explaining what they are, what they tell us about performance and why they matter. We’ll also look at how each parameter is measured, and how the results are used in both development, and production.

The first Audio Basics video is all about frequency response.

What is frequency response? Why is it useful in audio testing? Frequency response is one of the most fundamental measurements used to describe the performance and sound of a transducer, such as a loudspeaker, headphone, or microphone. This short educational video explains what frequency response is, how it is measured, and why it is one of the most important tools in electroacoustic testing.

Watch the Video Here:

Video Transcript:

Frequency response is one of the most fundamental ways to describe the way a transducer, such as a loudspeaker, sounds.

A speaker converts an electrical signal into an acoustic one, and its frequency response describes the magnitude of that conversion as a function of frequency.

In an ideal world, for any given input voltage, it would produce a constant output sound pressure level at each frequency.

However, in reality, deviations from this ideal response come from physical limitations, enclosure resonances, diaphragm breakup and more, and might look more like this.

We can see parts of the spectrum are emphasized and others are attenuated, and this is what gives a speaker its unique sound.

A boosted bass might be described as ‘warm sounding’, while a boost in the higher frequencies may make it seem more bright. What we describe subjectively as “bright,” “muddy,” or “neutral” largely maps back to frequency response.

Measuring frequency response enables objective comparison, informs design tradeoffs, and provides the baseline for equalization, calibration, and system optimization.

Measuring frequency response is simple. We play a test signal – usually a continuous sine sweep or log chirp, from 20Hz to 20kHz – through a speaker and capture the response with a calibrated precision microphone in a controlled environment. The response in dB is then plotted against frequency to show the frequency response graphically.

This is used in transducer R&D to design a signature sound, and also in production to ensure that the speaker is within spec.