Step One: The Source Produces a Digital Audio Signal
Every home theater experience begins at a source — a streaming device, Blu-ray player, cable box, or gaming console. These devices don't produce sound on their own. Instead, they output a compressed digital audio signal that contains all the information needed to recreate multichannel sound.
That signal is typically sent over an HDMI cable, which carries both audio and video in a single connection. Some setups use an optical (TOSLINK) cable for audio only, though optical has bandwidth limits that prevent it from carrying the newest high-quality formats.
The audio data at this stage is still encoded — meaning it's compressed and packaged in a format like Dolby Digital, DTS, or Dolby Atmos. Before you can hear anything, something in the chain has to decode it. For a broader look at how content reaches your TV in the first place, see every way to get content on your TV screen.
Step Two: Decoding Turns Data Into Distinct Audio Channels
Decoding is the process of unpacking that compressed signal into separate audio channels — front left, front right, center, surround left, surround right, and subwoofer (the classic 5.1 layout). More advanced formats like Dolby Atmos add overhead height channels, making sound appear to come from above as well as around you.
Decoding happens in one of two places:
- In the AV receiver — the most common approach in a traditional surround system. The receiver receives the raw encoded signal and does all the decoding internally.
- In the source device — some streaming devices or Blu-ray players decode the audio first and then send a pre-decoded signal (called PCM) to the receiver or soundbar via HDMI.
Either method can deliver excellent results. The key is that your hardware supports the same format as your content. If the source outputs Dolby Atmos but your receiver only understands Dolby Digital, it will fall back to the simpler format.
Bitstream vs. PCM: A Quick Clarification
When you see audio settings labeled 'Bitstream' or 'PCM' on a source device, you're choosing where decoding happens. Bitstream sends the raw encoded data to the receiver to decode; PCM means the source device has already decoded the audio and is sending uncompressed channels. Both approaches can deliver the same quality — the right choice depends on which device in your setup has the better decoder and which audio formats it supports.
Step Three: The Receiver Amplifies and Routes the Signal
Once decoded, each audio channel is still just an electrical signal — far too weak to move a speaker cone. The amplifier stage of an AV receiver boosts that signal to a level powerful enough to drive your speakers. Receiver power is measured in watts per channel; more power generally means the ability to fill a larger room or play louder without distortion.
The receiver also handles signal routing — sending the correct channel to the correct speaker. The center channel carries dialogue, the subwoofer handles deep bass, the front speakers anchor the soundstage, and surround speakers wrap you in ambient sound. This routing is configured during the receiver's setup process, which typically involves measuring your speakers with a calibration microphone.
5.1
Channels in a standard surround sound layout
The 5.1 format — five speakers plus one subwoofer — has been the baseline for home theater audio since the late 1990s and remains widely supported across content and hardware.
128
Maximum simultaneous audio objects in Dolby Atmos
According to Dolby Laboratories, Dolby Atmos can carry up to 128 simultaneous audio objects, each with its own position in three-dimensional space, allowing sounds to be precisely placed and moved.
If you're considering a simpler setup, a soundbar combines the decoder and amplifier into a single unit placed below or above the TV — no separate receiver required. Our guide to setting up surround sound without tearing up your walls covers wireless and soundbar-based options in detail.
Step Four: Speakers Convert Electrical Signals Into Sound
Speakers are the final and most physically obvious part of the chain. Each speaker contains a driver — a cone attached to a coil of wire sitting inside a magnet. When the amplified electrical signal passes through the coil, it creates a magnetic field that rapidly pushes and pulls the cone, moving air and creating the pressure waves you experience as sound.
Speaker placement and room acoustics play a major role in what you actually hear. Hard walls and floors reflect sound and can create echoes; soft furnishings absorb it. A well-placed set of modest speakers in an acoustically treated room will often sound better than expensive speakers in a bare, echoing space.
Run Your Receiver's Auto-Calibration First
Most modern AV receivers include an automatic calibration system — often called MCACC, Audyssey, or YPAO — that uses a small microphone to measure your room and adjust speaker levels, distances, and equalization automatically. Running this calibration before you start tweaking settings manually gives you a solid, room-optimized baseline and can dramatically improve the out-of-the-box sound.
For a plain-language explanation of terms you'll encounter on speaker spec sheets — like frequency response, impedance, and sensitivity — visit the home electronics glossary.
Frequently Asked Questions
An AV receiver decodes the audio signal from your source (like a streaming device or Blu-ray player), amplifies it, and sends the correct signal to each speaker in your system. It also acts as a central switching hub for all your HDMI and audio inputs, so you can connect multiple devices without rewiring anything.
Soundbars are convenient and can produce impressive sound, but a full surround system with discrete speakers placed around the room typically delivers more accurate and immersive audio. Soundbars use acoustic tricks — like bouncing sound off walls — to simulate surround effects, which works better in some rooms than others.
Dolby Atmos is an audio format that adds overhead height channels to the traditional surround sound setup, creating a three-dimensional sound field. You need both content encoded in Atmos and hardware that supports it — such as an Atmos-capable receiver and upward-firing or ceiling speakers — to experience the full effect.
HDMI ARC (Audio Return Channel) is a feature on HDMI ports that lets audio travel both ways over a single cable. It allows your TV to send audio from built-in apps directly to a soundbar or receiver without needing a separate optical cable. eARC (enhanced ARC) supports higher-quality formats like Dolby Atmos.
Audio-video sync problems (called lip-sync errors) happen when video processing takes longer than audio processing, so the picture and sound arrive at slightly different times. Most AV receivers and smart TVs have a lip-sync or audio delay adjustment setting in their menus that lets you manually re-align them.
The content on this site is for informational purposes only and is not a substitute for professional advice. Always consult a qualified professional for guidance specific to your situation.