Surround Sound Test — 5.1 & 7.1

This page drives each position of a 5.1 or 7.1 layout individually. On headphones it virtualizes the channels around your head with binaural processing; on a PC wired to a multichannel USB DAC or an HDMI AV receiver it addresses the discrete channels, letting you identify swapped wires, dead drivers, and mapping errors in minutes instead of hunting through a receiver menu.

How to use it

1. Choose your layout, 5.1 or 7.1, at the top of the room diagram. The diagram re-labels every node: front left (FL), front right (FR), center (C), LFE, surround left/right (SL/SR), and on 7.1 the rear pair (RL/RR).
2. Headphone listeners: nothing to configure. The binaural mode renders every channel through interaural delay and pinna filtering, so each node should sound like a distinct direction, not just “left” or “right.”
3. Receiver listeners: strip the processing chain. Set the OS output to 5.1 or 7.1 PCM (Windows: Sound settings > device Properties > Advanced channels; macOS: Audio MIDI Setup > Configure Speakers), then put the receiver in a pure pass-through mode, variously called Straight, Pure Direct, or Dolby Surround Off. Any dialogue enhancer, virtualizer, or upmixer in the path steals channels and makes a healthy system look broken.
4. Click each speaker node in turn, front left first, or run “Test All Speakers in Sequence” for the full circuit. Each click fires a short pink-noise burst from that position.
5. Name the direction before you look at the screen. Correct systems fool nobody: the center anchors dead-ahead on the screen line, surrounds arrive from the side and slightly behind, rears from behind.
6. Record every failure, then map it: a silent node is a wiring, fuse, or assignment problem; a burst from the wrong direction is a swapped pair; a thin front image is usually a missing center, not broken fronts.

Channel layouts and the angles behind them

The reference geometry comes from ITU-R BS.775, the ITU’s multichannel listening recommendation, which defines the speaker arcs used by Dolby Digital and Dolby Atmos beds alike.

5.1 (ITU-R BS.775)

• Front Left (L) and Front Right (R): placed at ±30° from the center axis so the three front speakers sit on a common arc around the listener. Carries the stereo bed: score, wide ambience, and most on-screen motion.
• Center (C): 0°, directly in front, at ear height. Anchors dialogue to the screen so mouths and words agree.
• Low-Frequency Effects (LFE): a dedicated channel with a 120 Hz playback low-pass and about 10 dB extra headroom relative to the five main channels. It carries designed effects (explosions, engine rumble), not a slowed-down copy of the main mix, which is why placement is flexible.
• Surround Left/Right (SL/SR): BS.775 puts the rear pair between 90° and 110°, to the side and slightly behind. Diffuse ambience and behind-you action.

Separately from the LFE channel, bass management reroutes low-frequency content from the five main channels down to the subwoofer; the industry-standard crossover point for home speakers is 80 Hz, chosen by THX so that small satellites stay out of trouble where the sub takes over.

7.1

Adds two rear surrounds (RL/RR) behind the listener at roughly ±135–150°, splitting the side ambience field from true rear localization so a helicopter can travel a full circle instead of jumping between two zones.

Channel reference

Channel	Reference position	Primary content	Symptom when it fails
FL / FR	±30°, ear height	Music bed, wide panning, action	Image drifts toward the surviving speaker
Center	0°, at or near screen line	Dialogue, on-screen effects	Vocals smear between fronts, “whispering reverb”
LFE	Anywhere reasonable, corner-assisted	Rumbles, impacts ≤ 120 Hz	No physical impact, or constant drone (hum, not LFE)
SL / SR	±90–110°, ~0.5–1 m above seated ears	Ambience, behind-side effects	Overhead action sounds stuck in front
RL / RR (7.1)	±135–150°, behind listener	Rear ambience, circle pans	Pans jump instead of orbiting

What you are listening for

Pink noise bursts are diagnostic because their energy is equal per octave from the tweeter down to the woofer (see the related Noise Generator for the spectrum math). A disconnected tweeter or rattling surround shows up as a change in the noise’s character, which a single tone would sail past unnoticed.

On headphones, the virtualization works by faking two physical cues: a sound from the left reaches the left ear up to about 0.65 ms sooner (interaural time difference) and arrives louder and spectrally reshaped because the head shadows the far ear (interaural level difference plus pinna filtering). Front-to-back and elevation errors are a known limit of any headphone simulation, so judge direction first and distance second.

One more failure only this test catches: inverted rear wiring. Swap the two conductors on one speaker and its burst will sound weak and smeared against the others, because the room sums 180°-out-of-phase energy into a null. The Speaker Test covers the stereo version of the same polarity check.

Accuracy, limits and troubleshooting

Browsers output what the OS device reports. If the system sees a 2-channel endpoint, every channel mixes down to stereo, and the discrete path collapses into the binaural experience. HDMI to an AVR or a multichannel USB DAC presenting a 5.1/7.1 layout is the only way to address real speakers.

The browser sends uncompressed PCM only. It cannot hand an AV receiver a Dolby Digital or DTS flag, so the receiver’s “Dolby” or “Atmos” indicator will stay dark no matter what plays here. That is a format fact, not a system fault.

Laptop speakers sit about 30 cm apart. Virtual rear arrival angles from that spacing are a suggestion, not a placement. Use headphones for the directional check.

Calibrate levels with the receiver’s own test tone, not this page: the conventional target is −20 dBFS pink noise matching at about 75 dB SPL on a C-weighted slow-response meter at the main seat, and Dolby’s Atmos installation guidance raises the target to 79–82 dB(C) for larger rooms. The Decibel Meter can sanity-check the room’s overall level, though phone- and laptop-class measurement mics roll off below 100 Hz, so trust the receiver for the sub channel.

A missing center on a true 5.1 system is usually the receiver’s speaker configuration (set to “None” or “Front Only”), not a blown driver: check that menu before blaming hardware.

Related tools

• Speaker Test — Stereo left/right, balance, and polarity verification for the front pair.
• Subwoofer Test — Diagnose the LFE path: extension, rattle, and crossover integration.
• Sound Localization Test — Probe the ITD/ILD cues this page’s binaural mode imitates.
• 8D Audio Test — A continuously circling binaural pan to stress-test your spatial hearing on headphones.