About

8D audio is a spatial audio technique that simulates sound rotating around the listener's head. The effect is produced by modulating a source's position along a circular path defined by x = r ⋅ cos(ωt) and z = r ⋅ sin(ωt), where ω is the angular velocity in rad/s. The human auditory system interprets these interaural time and level differences as directional cues. Headphones are mandatory. Speaker playback collapses the stereo field and eliminates the effect entirely. Poorly calibrated rotation speed causes listener fatigue. Too fast (> 0.5 Hz) induces disorientation. Too slow (< 0.05 Hz) becomes imperceptible.

This tool processes audio entirely in your browser using the Web Audio API. No file is uploaded to any server. The converter applies real HRTF-based panning via the browser's built-in spatial audio engine, combined with synthetic convolution reverb and a low-shelf bass boost filter. The result is rendered offline at full quality and exported as an uncompressed WAV file. Limitation: the spatial model assumes an idealized spherical head. Individual ear geometry (pinna shape) affects real-world perception and cannot be accounted for without personalized HRTF data.

Formulas

The 8D audio effect positions a virtual sound source on a circular orbit around the listener. At any time t, the source coordinates in the horizontal plane are:

x(t) = r ⋅ cos(2π ⋅ f ⋅ t)

z(t) = r ⋅ sin(2π ⋅ f ⋅ t)

Where r = rotation radius (m), f = rotation frequency (Hz), and t = elapsed time (s). The y coordinate remains 0 (no vertical movement).

The synthetic impulse response for reverb is generated as exponentially decaying white noise:

h(n) = noise(n) ⋅ e^{−3n ÷ (T ⋅ fs)}

Where T = decay time (s), fs = sample rate (Hz), n = sample index, and the factor 3 ensures −60 dB attenuation at time T (RT60 convention).

Bass boost uses a low-shelf biquad filter centered at 250 Hz with configurable gain G in dB.

Reference Data

Parameter	Recommended Range	Default	Unit	Effect on Output
Rotation Speed	0.05 - 0.5	0.15	Hz	Higher values create faster circular motion perception
Rotation Radius	1 - 20	8	m (virtual)	Larger radius increases perceived distance and stereo width
Reverb Decay	0.5 - 5.0	2.0	s	Longer decay simulates larger virtual rooms
Reverb Mix	0 - 100	30	%	Wet/dry ratio of reverb signal
Bass Boost	0 - 15	3	dB	Low-shelf filter gain below 250 Hz
Sample Rate	44100 - 48000	Source rate	Hz	Output WAV sample rate matches input
Bit Depth (Export)	16	16	bit	PCM encoding precision in exported WAV
Max File Size	≤ 50	-	MB	Browser memory constraint for decoding
Supported Formats	MP3, WAV, OGG, FLAC, AAC, M4A, WEBM (browser-dependent decoding)
HRTF Model	Browser built-in (Chromium uses IRC dataset from IRCAM LISTEN)
Panner Distance Model	`inverse` - gain = refDist ÷ (refDist + rolloff ⋅ (dist − refDist))
Channels (Output)	2	2	Stereo	Spatial panning requires stereo output
Angular Velocity (ω)	0.314 - 3.14	0.942	rad/s	Derived: ω = 2π ⋅ f

Frequently Asked Questions

The effect relies on interaural time differences (ITD) and interaural level differences (ILD) - subtle timing and volume variations between left and right channels. Speakers in a room create their own spatial cues from reflections that override the encoded panning. Headphones isolate each ear's signal, preserving the synthetic spatial information. Over-ear headphones produce a more convincing effect than earbuds due to better low-frequency reproduction and seal.

Slow ballads and ambient tracks work best at 0.08-0.12 Hz (one full rotation every 8-12 seconds). Pop and electronic music benefits from 0.15-0.25 Hz. Faster speeds above 0.3 Hz create a novelty "spinning" sensation that causes fatigue within 30 seconds. For tracks with prominent vocals, reduce the radius to 3-5 m to prevent the voice from sounding unnaturally distant at the far points of the orbit.

The Web Audio API processes internally at 32-bit float precision. The exported WAV uses 16-bit PCM, which matches CD quality (dynamic range of approximately 96 dB). If your source file is a lossy MP3 at 128 kbps, the output WAV will be larger but will not recover lost spectral information - you are spatializing the already-decoded signal. For best results, start with lossless sources (WAV, FLAC).

The preview uses the system AudioContext at its default sample rate (typically 44100 or 48000 Hz depending on your OS audio settings). The offline render uses the same rate as the source file. If these differ, the PannerNode HRTF interpolation may produce slight tonal differences. Additionally, the preview applies effects in real-time with potential buffer underruns on slower devices, while the offline render computes every sample without time pressure.

Stereo files are accepted. The tool decodes whatever channel layout the browser supports. The PannerNode automatically downmixes the input to mono internally before applying HRTF spatialization - this is a Web Audio API specification behavior. If your source has important stereo information (hard-panned instruments), that separation will be lost in the 8D version. For preserving stereo elements, consider isolating and processing stems individually.

The practical limit is approximately 50 MB file size, constrained by browser memory allocation for AudioBuffer decoding. A 10-minute WAV at 44100 Hz stereo 16-bit consumes roughly 100 MB of decoded float32 buffer memory. The offline rendering also allocates an output buffer of the same size. For files longer than 15 minutes, you may encounter out-of-memory errors on devices with less than 4 GB RAM. Mobile browsers are more restrictive.