If you have read specs on speakers, in all likelihood you have come across the terms, frequency response and frequency range. These are popular terms cropping up in discussions around headphones and speakers right on through to DACs and amplifiers, and even room acoustics.
These words get thrown around plenty in audiophile and consumer audio circles. That’s why we decided to put together the most useful information about both and ways to measure them.
What you need to know about Frequency Response and Frequency Range?
In simplest terms, frequency response is how even the frequencies are handled in terms of volume or loudness. Frequency response curve is difficult to interpret but it has some merit for the person who has experience.
Audio frequency range is how far the speaker goes in terms of bass and treble. That’s why a small bookshelf speaker may have a limited frequency range. It is the range over which it is considered to provide satisfactory performance.
- Frequency response refers to the accuracy of frequency measurement across a given range. In online motor testing, an example is a frequency response from 10Hz to 20kHz with a tolerance of +/- 3dB. The tolerance (+/- dB) refers to how accurate the measurement is across a given frequency range. The lower the +/-dB number, the higher quality the frequency response and the more accurate the measurement is.
- Frequency range refers to the range of frequencies which the equipment is capable of measuring, but without reference to the accuracy or "flatness" of the actual response across the range. For example, the frequency range from 10Hz to 20kHz with a tolerance of +/-10 dB is very poor quality in comparison to the tolerance of +/- 3dB from the previous example.
How to Measure the Frequency Response?
Frequency Response, Continuous Sweep, Acoustic Response, and Loudspeaker Production Test are all based on the exponential sine sweep, or chirp, technique pioneered by Angelo Farina in 2000. These techniques use the same signal processing technique.
Other popular techniques include:
- Acoustic Response: This test allows you to apply a time window, or gate, to the impulse response.This can be used to window out the acoustic reflections that occur when making measurements in a non-anechoic space (reverberation room).
- Loudspeaker Production Test: It measures not just the frequency response, distortion, phase response, impulse response, and rub and buzz of a speaker, but also adds the impedance response and Thiele-Small parameters of a speaker, using the chirp stimulus signal.
- Stepped Frequency Sweep: Stepped frequency sweeps are the de facto standard for many devices and for comparison purposes it is often required to use this measurement.
- Bandpass Frequency Sweep: It is also a stepped sine sweep measurement, yet in this measurement context a filter with potentially high-selectivity is useful in tracking the fundamental stimulus signal.
Understanding Audio Frequency Range
The audio frequency spectrum represents the range of frequencies that the human ear can interpret. Usually, audio frequency range is 20 Hz to 20,000 Hz,however, most people can hear less than this entire range, and as they get older, the range tends to contract on both ends.
Here are the seven subsets of frequencies used to help define the ranges to effectively target in designing systems for either recording or playback.
|16 to 60 Hz
|Low musical range - an upright bass, tuba, bass guitar, at the lower end, will fall into this category
|60 to 250 Hz
|Normal speaking vocal range
|250 to 500 Hz
|In the lower midrange are typical brass instruments, and mid woodwinds, like alto saxophone and the middle range of a clarinet
|500 Hz to 2 kHz
|Higher end of the fundamental frequencies created by most musical instruments. For instruments like the violin and piccolo
|2 to 4 kHz
|Harmonics are at multiples of the fundamental frequency, so if expecting the fundamentals for a trumpet to be in the lower midrange, one can expect the harmonic to be at 2 times, 3 times, and 4 times that fundamental, which would put them in this range
|4 to 6 kHz
|Harmonics for the violin and piccolo are found here
|6 to 20 kHz
|Above 6 kHz the sounds are high pitched. In this range, sibilant sounds (the unwanted whistle when sometimes pronouncing an ‘s’) and harmonics for certain percussive sounds like cymbals are found
The link between music and audio frequency is that each time you move up an octave, you double the frequency.
The audio frequency range is a large portion of design and component selection with speakers, buzzers, enclosures, and microphones.
Hopefully, this blog provided you some helpful insights into the terms like frequency range and frequency response. Our experts at Ooberpad are just a quick call and click away. Reach out to us if you have any questions.