A gimmick for VRChat avatars

HeartBeat

Heartbeat Gimmick

A quiet heartbeat that plays only when someone's head touches your chest. This VRChat avatar gimmick includes 4 "chimera heartbeats" — hearts of a large animal and a human layered into one.

Modular Avatar support VRChat Contact-driven 2-bit synced parameters

See setup steps Included heartbeat sounds

The heartbeat plays when someone's head enters the detection zone on the chest (radius 0.20 m). Since the sound itself carries only up to 0.17 m, it's audible only to that person, and only while they're touching.

Features

A quiet heartbeat, only when touched

It doesn't play continuously. The heartbeat is heard, at a volume confined to close range, only while someone's head is touching your chest.

Plays on contact

A VRChat Contact Receiver detects the Head tag (a player's head). It plays only while touching, and stops the moment contact is broken.

Sound confined to close range

Attenuation is set to Near 0.12 m / Far 0.17 m. It never reaches bystanders further away, so it won't intrude on the surrounding soundscape.

Four heartbeat sounds included

Original sounds that layer the heartbeats of a large animal and a human into a single pulse. Four variations, each with a different weight and tempo, are ready — just swap the AudioClip to choose.

Drag-and-drop setup

Built on Modular Avatar components. Just drop it onto your avatar — the menu, parameters, and FX layer are all merged automatically on upload.

Auto-follows the Chest bone

MA Bone Proxy attaches to the avatar's Chest bone at runtime. The positioning on the chest is preserved even if the base body changes.

Toggle on/off from the menu

Adds one toggle to your Expressions menu. Turn the whole gimmick off when you don't want it (defaults to ON, saved).

Setup

Setup steps

If your Unity project already has Modular Avatar installed, this works in 3 steps.

Install Modular Avatar

First, install Modular Avatar into your project. Without it, the menu and parameters won't be merged in.

Add the prefab to your avatar

Drag and drop HeartBeat.prefab anywhere under your avatar in the Hierarchy. The exact position doesn't matter — it moves to the Chest bone automatically at runtime.

Adjust position and range for your body

Select the child object Origin and position it at the center of the chest. If the detection zone is too wide or too narrow, adjust Radius (default 0.2) on the VRC Contact Receiver.

To change how far the sound carries, adjust Far (default 0.17) on the same Origin's VRC Spatial Audio Source.

To change the heartbeat sound. Swap the AudioClip on Origin's AudioSource for one of HB_Chimera1 through HB_Chimera4. HB_Chimera1 is set by default.

Sounds

Included heartbeat sounds (4 variations)

All four are original "Chimera" series sounds, synthesized from the heartbeats of a large animal and a human. Each differs in weight, tempo, and density. Loop lengths are matched, so swapping between them leaves no seam.

HB_Chimera1 Default

A calm, low, steady heartbeat

A calm, low heartbeat kept to a perfectly steady rhythm. The highest audio quality in the series.

Format: MP3 / 48,000 Hz / Stereo / 320 kbps
Length: Approx. 6.24 s (looped)
Rhythm: Approx. 63 bpm, 6 beats

HB_Chimera2

A slight variation on Chimera 1

Another take at the same tempo as Chimera1, mixed for a lighter, more natural texture. Also has a smaller file size.

Format: MP3 / 48,000 Hz / Stereo / 128 kbps
Length: Approx. 6.29 s (looped)
Rhythm: Approx. 63 bpm, 6 beats

HB_Chimera3

A human × large-animal fusion heartbeat

Built on the low, heavy heartbeat of a large animal, with a human's fast, high-pitched heartbeat layered on top like an overtone. Tempo follows the large animal's — a slow, heavy pulse.

Format: MP3 / 48,000 Hz / Stereo / 320 kbps
Length: 6.240 s (looped)
Rhythm: 2.08 s cycle (approx. 29 bpm), 3 beats
Composition: Large animal (base) + human (mix ratio 0.55)

HB_Chimera4

A triple-layered fusion heartbeat

The densest sound in the series, stacking a large animal's low heartbeat with a mid-range body resonance and a human's bright overtones. Slightly faster than Chimera3.

Format: MP3 / 48,000 Hz / Stereo / 320 kbps
Length: 6.240 s (looped)
Rhythm: 1.56 s cycle (approx. 38.5 bpm), 4 beats
Composition: Large animal (1.0) + mid-range heartbeat (0.7) + human (0.5)

Unity import settings (common to all 4 files)
Item	Value	Rationale
Load Type	Decompress On Load	Eliminates delay at playback start. Memory cost is low, since the loop is short
Compression Format	Vorbis / Quality 1	Keeps avatar size down while preserving the low end of the heartbeat
Force To Mono	Off	Stays stereo, so spatial positioning isn't lost
Normalize	On	Evens out loudness across the 4 variations
Load In Background	On	Doesn't block world loading
Spatialize (3D)	On	Positions the sound as if it's coming from the chest

How it works

Driven by two independent layers

Whether the gimmick itself is on, and whether someone is currently touching, are handled by two separate layers. Turn it off from the menu and it stays silent even on contact.

Reference

Parameters and configuration

Only two synced parameters are used on the avatar (two bools = 2 bits).

Expression parameters
Name	Type	Synced	Saved	Default	Role
HeartBeat	bool	Yes	Yes	ON	Turns the whole gimmick on/off. Controlled from the menu toggle
HeartBeat_Contact	bool	Yes	No	OFF	Whether a head is touching. Written automatically by the Contact Receiver

Key adjustable values (on `Origin`)
Component	Item	Default	Description
VRC Contact Receiver	Radius	0.2	Radius of the sphere that detects a head (m). Larger makes it easier to trigger
VRC Contact Receiver	Position	Z +0.03	An offset that pushes the detection sphere slightly in front of the chest
VRC Contact Receiver	Collision Tags	Head	The body part it reacts to. Limited to the head only
VRC Contact Receiver	Allow Self / Others	Both on	Reacts to both your own head and other players' heads
VRC Spatial Audio Source	Near	0.12	No attenuation up to this distance — plays at full volume (m)
VRC Spatial Audio Source	Far	0.17	Beyond this distance, it becomes inaudible (m)
VRC Spatial Audio Source	Gain	10	Volume. Since the audible range is extremely narrow, this keeps close-range presence strong
AudioSource	AudioClip	HB_Chimera1	The heartbeat sound to play. Choose and swap from the 4 variations
AudioSource	Loop	On	Repeats while contact is maintained

Included files
File	Contents
HeartBeat.prefab	The gimmick itself. Includes a full set of Modular Avatar components
HB_Chimera1-4.mp3	The 4 heartbeat sounds
HeartBeat.controller	AnimatorController (2 layers)
On.anim / Off.anim	Gimmick on/off
Play.anim / Stop.anim	Heartbeat play/stop
Menu.asset / Params.asset	Expressions menu and parameters, for merging manually without the prefab

Notes

Before you install

Due to how Contact and spatial audio work in VRChat, there are situations where it simply won't function.

Won't trigger if the other person's Contact is disabled

If Contact is turned off by the other person's settings or Safety state, touching won't get a response. It only works with people who have contact enabled.

Modular Avatar is required

Menu, parameter, and FX layer integration is handled by Modular Avatar. Uploading without it installed won't work.

Requires an avatar with a Chest bone

MA Bone Proxy attaches to the Humanoid Chest bone. On rigs where Chest isn't assigned, there's nowhere for it to follow to.

The sounds are entirely fictional

They aren't recordings or processing of real biological data — every sound is a synthesized creation. They aren't intended for medical or biometric use.