The eight sound presets
Each preset shapes the timbre and attack of the tone — the underlying
carrier frequency and the pan rate are independent controls.
Carrier frequency
The frequency slider is set to 250 Hz by default and clamped to 200 to 450 Hz. This is the pitch of the carrier tone underneath whatever preset you’ve chosen. Most clients tolerate the 200–300 Hz range well — high enough to be clearly audible without being shrill, low enough to feel grounded. Move higher (350–450 Hz) for clients who prefer a brighter feel; move lower for clients who report the higher range as fatiguing.Where the tone sits
The tone isn’t matched to the movement — it is the movement. Where the stimulus sits on its path and which ear the tone is in are the same value, worked out once and used for both. There’s no second clock keeping the sound in step with the picture, so the tone can’t slide behind the stimulus over a long set and can’t drift when you change the speed partway through. That matters because you can’t hear your client’s audio from your side of the screen. If a tone lagged the stimulus, nothing on your side would tell you. See One movement, not three. Hard panning is intentional. This is not binaural beats — binaural beats use two slightly detuned tones in different ears and are a different mechanism (entrainment) not validated for EMDR. Rivet’s audio modality is straight stereo panning of a single tone, matching the in-office BLS hardware convention.Volume
A 0 to 100% slider. The default is 60%. The client’s device volume sits on top of this — a 60% Rivet volume with the client’s phone muted produces no sound. If the client reports they can’t hear the audio, ask them to check their device volume first.iOS Safari handling
iOS Safari blocks audio playback until the user makes a gesture. Rivet sets up the audio at the moment the client taps Join — granting camera and mic permission counts as the gesture — so audio just works when BLS starts. This was historically the #1 BLS support category across the industry. Rivet sidesteps it by setting up the audio at the moment the client taps Join, not when BLS starts.When the audio stops
The tone stops when the set stops and when the session ends. Nothing keeps playing in the background afterwards — there’s no version of this where your client is still hearing the tone once you’ve both left.Headphones vs speakers
For optimal BLS, the client should use stereo headphones. Earbuds work. Laptop speakers technically work but the L↔R panning is far less distinct when both speakers are 6 inches apart, and phone speakers (single mono output) lose the bilateral effect entirely. In your reminder email or pre-session message, suggest the client have headphones or earbuds ready. See Best practices for virtual EMDR.Related articles
Visual bilateral stimulation
The visual modality — stimulus shapes, motion paths, and the 0.3 to
2.0 Hz speed range.
Best practices for virtual EMDR
Headphones, browser window, client environment, and choosing modalities
for a given client.
Setting up an EMDR session
The Configure modal walkthrough — including the modality picker and
sound preset row.