Look at earbuds, home theater systems, or any number of audio electronics, and you’ll see the term “digital signal processing” (DSP) floating around. Let’s take a look at what this term actually means and what it does to your audio.
The basics of digital signal processing explained
For a term so casually used in marketing, DSP is a very complex subject. At a basic level, all digital signal processing does is take a signal – for our purposes an audio signal – and manipulate it digitally to achieve a particular desired result.
That sounds simple, but the actual processing and algorithms used can be incredibly complex. A simple task like increasing the volume to a certain amount can be relatively easy, but something like adaptive noise cancellation is a much more difficult task to perform.
Sometimes you see a product such as headphones described as “a DSP”. In this case, the initialism represents a digital signal processor. All this means that the product has a chip that processes audio signals in certain ways.
Having a DSP chip is more common in devices that you wouldn’t necessarily expect to have built-in processing, such as headphones. Digital signal processing is used in many other places, such as your phone or computer, but because those devices already have powerful built-in processors, there is often no need for a separate digital signal processing chip.
Even in systems with traditional CPUs, you will occasionally come across DSP-specific chips. This is because the processing of audio signals has to be done in real time, so optimized circuits can improve this kind of performance.
General Digital Signal Processing Applications
Digital signal processing is capable of doing extraordinary things, but also has simple applications. For example, when listening to a music playlist, many players use DSP to ensure that there are no huge volume jumps between songs.
Analog-to-digital conversion and digital-to-analog conversion are another common use case for DSP. Often the conversion takes place in a specialized DSP chip dedicated to this purpose, called a DAC or AD/DA converter, depending on whether it is only being converted in one direction. Converting real audio signals into digital signals is an art in itself, which is why there are a number of expensive converters on the market.
One use for DSP that you are likely to encounter and which you will pay attention to on a regular basis is noise reduction. A combination of external microphones on your headphones and digital signal processing dampens the sounds around you.
The flip side of that same coin that also uses DSP is Transparency Mode, as Apple calls it. This one uses the same microphones that make noise cancellation possible, but instead of canceling them out, it amplifies the sound so you can hear your surroundings more easily.
Digital EQ is another common use for digital signal processing. If you’ve ever used a music app on your phone or computer that lets you adjust the EQ, this is digital signal processing in action. When you adjust a slider, the processing digitally increases or decreases the amplitude of certain frequencies.
A final example is room correction. Many home theater systems now include a system to automatically adjust various settings to ensure the sound is optimized for the size and shape of your room. It also sets the timing for each speaker so that the sound reaches your couch in perfect sync.
When is DSP important to you?
Asking when digital signal processing is important may seem like an odd question, but there are times when it’s crucial. For audio, there are certain aspects of products where you should pay close attention to the type of digital signal processing or the manufacturer of the DSP chip.
As mentioned, if you’re buying a headphone amp or A/V receiver, the better the AD/DA converters are, the better they’ll sound. You’ll still hear everything fine with a lower quality converter, but if you consider yourself an audio enthusiast, you won’t want to go for the cheapest components.
Noise reduction is another area where the quality of both the DSP chips and the algorithms running on them make a huge difference. Not all noise cancellation is created equal, so be careful when buying earbuds or headphones.
At the same time, built-in EQ in headphones or different sound modes on Bluetooth speakers and A/V receivers are not so important. In many cases, these are new features first and foremost, so the quality of processing used for these features shouldn’t play such a big part in your purchasing decisions.
Knowing what’s important to you is essential, so don’t worry too much about DSP features if you know you won’t be using them often.