What is DSP? Digital signal processing explained
By Sam McNiece
Explore the computer chip that allows us to listen to, manipulate and record audio in the digital sphere.
In the modern age of recording, mixing and mastering, built-in DSP effects are becoming an increasingly common feature for audio interfaces. Universal Audio has led the charge in this regard, but there is now a plethora of manufacturers creating interfaces with effects processing that can be printed onto incoming audio signals with zero latency.
What makes all of this possible are DSPs (Digital Signal Processors) which have become increasingly needed in the audio world throughout the digital audio revolution. In light of this, we’re taking a deep dive into DSP today, asking ourselves what it is, how it’s used, and why it’s important.
- A digital signal processor is a computer chip that manipulates incoming signals based on mathematical equations and generates a result in real time.
- DSPs are used whenever audio is processed in the digital domain, which could be in a DAW, speaker, interface, or even your phone.
- The importance of DSPs is obviously true in today’s digital audio environment, where our computers can perform tasks that used to be relegated to physical hardware units such as compressors and recording consoles.
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What is DSP?
In a nutshell, a digital signal processor (DSP) takes an incoming signal, manipulates it based on math, and generates a result. You can think of a DSP as a very fast calculator that executes complex equations in very short time frames. A common example of DSP in the audio arena is Universal Audio’s line of interfaces that use a built-in DSP to add compression and other effects to your input signal without latency without using the precious processing power of your computer.
DSPs in the computer audio space are typically independent chips that work in tandem with a processor and graphics processor, doing most of the signal processing. They are specially designed for real-time data streams and are designed to be fast during specific mathematical calculations.
On a more in-depth computer level, a DSP is also used in audio recording and output. An analog-to-digital converter (ADC) will take an input (a microphone for example) and convert the analog signal into binary digits before transmitting this information to the DSP which will process the now digitized audio signal and allow it to be recorded to disk. The same can be said to go in the opposite direction, in which the DSP receives the recorded audio, processes it and then passes it to a digital to analog converter (DAC) to play the audio on the speakers.
With this latter example, the processing done by a DSP can be as simple as decoding it for playback, but in more complex cases can be used to alter the frequency response via EQ or compression and even allow cancellation. active noise (ANC).
How is the DSP used?
Digital Signal Processing (DSP) is the foundation on which DAWs (Digital Audio Workstations) operate. In other words, without DSP, there would be no DAW. Every change you make to an audio signal in the DAW environment uses DSP. That makes sense, doesn’t it? As we modify a digital audio signal using the computer Processing Power. Each plugin added to a DAW uses the processing power of your computer or interface and allows you to add effects such as reverb and saturation effects to digital space.
Some uses of DSP are more computationally intensive than others. For example, a native plug-in effect in Ableton uses much less processing power than an external Waves plug-in, because native plug-ins are optimized for use in this environment.
Even in live audio, most audio data is now connected via Ethernet cables to transmit digital audio from the stage to the digital mixer. Using these digital consoles, DSPs are at the forefront of their existence, enabling the complete mixing process to be completed in the digital realm, a milestone compared to using multicore cables over long distances up to to the mixing position of a festival.
As processing power continues to improve over time, DSP is increasingly used in audio products. Examples that stand out would be Nura’s line of headphones, which use DSP to change the frequency response of their speakers based on a unique hearing profile or the Genelec monitors which use DSP to correct for hearing anomalies. room and properly delay the speakers according to their placement.
In more consumer audio products, smart home devices like Alexa or Siri use DSP to convert our voice into digital commands that can be used to change the lighting in your home or even search the internet.
This only scratches the surface of the uses of DSP in audio because by nature every digital audio product and software uses digital signal processing in one form or another.
Why is DSP important?
In the modern sphere of digital audio, DSPs are the main component that we use every day (whether we are aware of it or not), to create, modify and listen to music. Your computer’s 3.5mm jack output is managed by DSP and allows your headphones to receive the correct information so you can listen to Lorde’s new record on repeat all day.
DSP also allows our phones and computers to pick up the analog signal from our voices and process it for transmission over the Internet, for example via Zoom, which in turn uses DSP to suppress background noise and optimize playback. your voice by learning how your the sounds of the room.
In modern loudspeakers, digital signal processors allow EQ, filters and compression to be applied alongside more compute-intensive uses like Genelec’s GLM processing. Even your wireless headphones will have a form of DSP, acting as the link between your Bluetooth connection and the physical audio waves generated by small devices (not to mention the active noise cancellation present in a few models).
Overall, DSPs are the most important link in the digital audio chain and allow audio products to perform more efficiently thanks to specialized chipsets. The next time you’re listening to your favorite record, think about how DSP probably made this possible.
To learn more about DSP, check out this video explanation of the process.