Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies.
In audio systems bandwidth is simply the range of frequencies that an audio system can process. This is usually between 20 Hertz to 20,000 Hertz. This is the frequency range that the human ear can pick up.
Bandwidth represents the width of a frequency band;
Expressed mathematically, the width is the highest frequency minus the lowest frequency.
In human hearing for example, the bandwidth of a person’s ears is about 20,000 Hz – 20 Hz = 19,980 Hz.
It is typically measured in hertz, and depending on context, may specifically refer to passband bandwidth or baseband bandwidth.
Passband bandwidth is the difference between the upper and lower cutoff frequencies of, for example, a band-pass filter, a communication channel, or a signal spectrum.
Baseband bandwidth applies to a low-pass filter or baseband signal. The bandwidth is equal to its upper cutoff frequency.
Bandwidth in Audio
In audio we use various frequency analysis digital tools to help us view the frequency array of any sound be it an instrument or a voice.
This is necessary for audio processing.
Understanding the bandwidth of equipment, instruments and vocals serves as the fundamental operating principle which helps us in carrying out effective work.
In the simplest sense bandwidth is simply the span of frequency.
There are a number of other definitions in different contexts but in audio… we are only speaking of the span of frequency from lowest to highest.
The audio bandwidth is typically given as 20 Hz to 20,000 Hz, although there are some harmonic components of audio that go beyond the 20,000 Hz point.
Harmonic components may come in as additional content when we, for example, use tools like saturators to give warmth and brightness to an audio signal.
In situations where bandwidth is given as an audio spec, you need to go for the audio device with a wider frequency range.
Its therefore important that when comparing bandwidth on different devices, that the same spec is being expressed.
For example, some effects devices may cite their bandwidth spec based on the dry, or unprocessed signal, while others give the bandwidth of the actual processed sound.
The difference between these two specs that could be both listed as “bandwidth” can be significant and it pays to pay attention to details.
The bandwidth on an amplifier is another thing that one has to take into consideration when looking to buy or use one.
Ideally, any amplifier must have a bandwidth that is suited to the range of frequencies it is intended to amplify.
For example, if you have a bass guitar that you need to amplify, you need to pay attention to the amplifier specs to make sure that it won’t leave out any frequency content of the bass.
If the bandwidth of the amplifier is too narrow the result will be a loss of some signal frequencies.
If the bandwidth is too wide, there will be an introduction of unwanted signals.
In the case of an audio amplifier for example these would include low frequency hum and some mechanical noise, and at high frequencies like hiss.
Microphone bandwidth is not something that you’ll come across.
You’ll mostly find frequency response specified on the mic specs.
In choosing a microphone for vocals, going for a microphone with a frequency response range of around 80 Hz to 15 kHz would make for a good choice.
However, if you’re considering miking instruments like snares and toms, you would basically look for a range that starts lower, at around 50 Hz, and for a bass drum mic, you will want a low end of 40 Hz or even lower, down to around 30 Hz.
Speaker Bandwidth/Frequency response
Bandwidth and frequency response are essentially the same thing, in audio equipment.
However, the power bandwidth is different because of the specific way it is cited.
The concepts are general and basic, but the way they are cited and specified make each case different.
Citing a frequency response/bandwidth must be defined by citing the way the end points are defined, or the whole thing is essentially meaningless.
For example, a speaker’s bandwidth/frequency response is usually specified as some low and high frequency limit minus 3DB.
This means that the limits are the low (and high) frequencies where, with a constant input voltage to the speaker at all frequencies, the sound power coming out of the speaker drops off to half of what it was across the middle frequencies.
The speaker bandwith is therefore defined from the Low frequency 3db frequency to the High Frequency 3db frequency.
Sometimes speaker bandwidth is specified without saying how many db down defines the High Frequency and Low Frequency end points.
In this case the bandwidth given is meaningless, since the basis for the end points is undefined.