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 digitally manipulate it to achieve some sort of desired result.
That sounds simple, but the actual processing and algorithms used can be incredibly complex. A simple task like increasing volume a certain amount may be relatively simple, but something like adaptive noise cancellation is a much tougher task to handle.
You’ll sometimes see a product like headphones described as having “a DSP.” In this case, the initialism stands for a digital signal processor. All this means is that the product has a chip that is dedicated to processing audio signals in certain ways.
Having a DSP chip is more common in devices that you wouldn’t necessarily expect to have processing built-in, like headphones. Digital signal processing is used in plenty of other places, like your phone or computer, but because those devices already have powerful processors built in, there is often no need for a separate chip dedicated to digital signal processing.
Even in systems with traditional CPUs, you’ll occasionally see DSP-specific chips included. This is because audio signal processing needs to happen in real-time, so optimized circuits can improve this type of performance.
Common Uses For Digital Signal Processing
Digital signal processing is capable of doing extraordinary things, but it also has simple uses. When you’re listening to a music playlist, for example, many players use DSP to ensure that there aren’t massive volume jumps between songs.
Analog to digital conversion and digital to analog conversion are another common use case for DSP. Often, the conversion will take place in a specialized DSP chip meant specifically for this purpose, known as a DAC or AD/DA converter, depending on whether it only converts one-way. Turning real-world audio signals into digital signals is an art in itself, so you’ll find some costly converters on the market.
One use for DSP that you probably encounter and pay attention to more regularly is noise cancellation. A combination of external microphones on your headphones and digital signal processing cancels out the sounds around you.
The flip side of that same coin that also uses DSP is Transparency Mode, as Apple calls it. This uses those same microphones that make noise cancellation possible, but instead of canceling it out, it amplifies the sound, letting you more easily hear your surroundings.
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 amplifies or lowers 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 make sure that 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 perfectly in sync.
When Does DSP Matter to You?
Asking when digital signal processing matters might 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 earlier, if you’re buying a headphone amp or A/V receiver, the better quality the AD/DA converters, the better it will sound. You’ll still hear everything fine with a lower quality converter, but if you fancy yourself an audio enthusiast, you won’t want to go with the cheapest possible components.
Noise cancellation is another area where the quality of both the DSP chips and the algorithms running on them makes a massive difference. Not all noise cancellation is created equal, so you’ll want to make sure to pay close attention when buying earbuds or headphones.
At the same time, onboard EQ in headphones or various sound modes on Bluetooth speakers and A/V receivers aren’t as important. In many cases, these are novelty features in the first place, so the quality of the processing used for these features doesn’t need to factor as heavily into your purchasing decisions.
Knowing what matters to you is essential, so don’t sweat too much over DSP features if you know you won’t be using them all that often.
