Friday 12th August 2022

What Is a Sound Card and How Does It Work?


Most of us take sound for granted. After all, when we buy a computer or a laptop, it has a built-in speaker or a readily accessible audio plug.

But back in the day, this wasn’t the case. Computers could only make one sound—a beep. Although you could change its pitch and length, it wasn’t particularly realistic.

So, to recreate sounds as we hear them, manufacturers created sound cards. So, here’s how a sound card works and whether you need one for your PC.

The Basics

Ear on a white cardboard

Sound is an inherently analog signal—it is created through vibration. The air molecules surrounding the object then vibrate with it. As those air molecules move around, they hit other air molecules, thus propagating sound.

We hear sound when these vibrating air molecules contact our eardrums. Our eardrums transmit the vibrations into the inner ear. Our nerves there convert the vibrations into electrical impulses to let us hear music.

Computers, on the other hand, talk digitally. They transmit electrical signals in 1s and 0s. These are basically just on and off signals. They don’t translate into sound, so they need to be converted from digital into analog signals.

This is where the sound card comes in. The computer sends data to the card, which it then processes and converts to an analog output.

How Sound Cards Work

Analog Devices chip from Singapore

Most sound cards have four major components:

  • A Digital-to-Analog Converter (DAC)
  • An Analog-to-Digital Converter (ADC)
  • A PCIe interface
  • Input and output connections

Some cards use a coder/decoder chip, called a CODEC, which performs both the DAC and the ADC functions.

When your computer plays audio, it sends a signal to the sound card via the PCIe interface. That signal passes through the DAC before being pumped out of the output connection.

Recording audio on your computer follows the same process but in reverse. Your sound card receives signals via the input connection. It’s then converted in 1s and 0s via the ADC. Afterward, the card sends the signal through the PCIe into your CPU for processing.

Digital Signal Processing Chips

Furthermore, other sound cards have a digital signal processor (DSP) and an amp. A DSP is a microprocessor specifically designed to process audio. It provides the processing power required by the DAC/ADC/CODEC to convert signals. If your sound card doesn’t have a DSP, it uses your CPU for this conversion.

The amp or amplifier, on the other hand, is used for strengthening the output signal. If the converted signal is weak, the amp uses electric power to increase its amplitude. This increases the output volume of the audio.

Do You Need a Sound Card?

Headphones beside a CPU

Honestly, most users don’t need an independent sound card. In the 80s and 90s, computers required a separate sound card. This is because processors back then weren’t powerful enough to process audio.

But as technology progressed, processors gained enough power not to need sound cards anymore. That’s why most pre-built computers and laptops don’t have a separate sound card.

The built-in sound card on most computers is adequate to provide quality audio for you. But if you’re working with sound professionally or have a 7.1 surround sound home theater, you probably need one.

Some gamers also use sound cards to improve their performance. This is because some of these cards use surround-sound virtualization. This technology transforms 3D sound into a stereo output for headsets. Players can then use auditory cues to find their enemy’s position.

Related: How to Enjoy Spatial Sound With Windows Sonic for Headphones

What to Look for in a Sound Card

If you want the best audio experience, a sound card is the way to go. But with so many options out there, what should you look for?

1. 3D Spatial Imaging

This feature allows 3D effects to be converted into stereo output. While gamers benefit most from this, it also adds immersion to both audio and video.

If your sound card has 3D Spatial Imaging, it can process audio from movies to make it feel like you’re in the thick of the action. It can also add effects to your music and make it feel as if you’re listening in a concert hall.

2. Surround Sound Technology

Surround sound speakers

If you have a 5.1 home theater system, then you need a sound card that supports this. These sound systems use five speakers (or more) and a subwoofer to give you immersive sound.

If your sound card doesn’t support surround sound technology, you won’t get the most out of your home theater. But if your sound card supports surround sound, it will most likely support 3D spatial imaging too.

3. S/PDIF Support

Most home theaters have a S/PDIF connection. S/PDIF stands for Sony/Phillips Digital Interconnect Format. It was primarily designed by Sony and Phillips to transmit uncompressed, high-fidelity audio.

If you want to take advantage of this, your sound card must have a S/PDIF port to connect your home theater.

4. MIDI Ports

MIDI Keyboard Connected to a Computer

If you’re a musician and want to record your instruments on your PC, you need to have a MIDI port. MIDIs don’t just record audio; they can also record specific musical instructions.

For example, MIDI software will include notation, pitch, volume, vibrato, panning, tempo, and more when recording music through a MIDI port. This makes it easier for musicians to change aspects of their music on the fly.

Sound Cards vs. DACs

A DAC connected to a pair of headphones

As explained earlier, DACs are essential for any sound card to work. But if you look in the market today, you can also find external DACs available for purchase.

DACs are essentially external sound cards without a built-in processor. They’re primarily designed to do a straightforward conversion of a digital signal to analog.

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