Alternating bilateral stimulation should be clearly distinguishable from side to side. If one tapper feels weaker, one headphone channel seems quieter or the timing appears uneven, the safest response is not to compensate immediately by increasing intensity. Stop and check what is happening.
An apparent left–right difference can come from the equipment, a connection, headphone orientation, how a component is being held or fitted, or the client’s sensory experience. A brief, neutral check can help identify the practical issue without turning the equipment into a diagnostic tool.
Start by stopping the set
Pause bilateral stimulation before touching plugs, moving headphones or changing controls. Ask the client to describe the difference in concrete terms:
- Does one side feel or sound weaker?
- Is one side absent entirely?
- Does the difference happen every time or only occasionally?
- Is the concern about strength, clarity, timing or comfort?
- Did it begin after the client changed grip or headphone position?
Avoid suggesting that asymmetry has a psychological meaning. The immediate task is to determine whether the stimulation is functioning as intended and remains acceptable to the client.
Check the basic connections
The Mangrove Inspired Simple EMDR Set connects two wired tappers to separate sockets on the master controller and provides a stereo headphone output for auditory stimulation. Before testing again:
- confirm that each tapper cable is fully seated at both ends;
- check that the lightbar and audio accessories are connected to their labelled sockets;
- look for obvious cable damage, sharp bends or connector strain;
- make sure the headphone plug is fully inserted; and
- confirm that an inline volume control, if used, has not been moved accidentally.
Do not connect or disconnect components while a set is running. If a plug or cable appears damaged, remove it from clinical use and seek product support rather than trying to hold it in a working position.
Checking the tappers
On the Mangrove system, the tapper LEDs indicate which side is active and change brightness with the amplitude setting. These indicators help confirm that the controller is sending an alternating signal, although they do not measure how the client experiences the pulse.
A simple check can proceed as follows:
- Set a conservative amplitude.
- Hold both tappers yourself and run a brief neutral set.
- Confirm that the LEDs and tactile pulses alternate.
- Check whether either connection cuts in and out when the cables rest naturally.
- Ask the client to hold the tappers in their usual position.
- If appropriate, swap the tappers between hands and repeat briefly.
If the reported difference consistently follows one tapper, cable or socket, stop using the affected component and contact the supplier. If the difference remains on the same side of the client after the tappers are swapped, that observation may be clinically relevant, but it is not a diagnosis and should not be interpreted by the equipment alone.
Grip and contact can change the experience
Tappers may feel different when one is gripped tightly, held against a different part of the hand or partially cushioned by clothing or another object. Ask the client to hold both in a comparable, comfortable way without requiring a forceful grip.
Do not increase amplitude on both sides simply to overcome an uncertain difference. First establish that the components are working consistently and that the client’s grip and contact are comparable.
Checking stereo audio
Auditory bilateral stimulation depends on separate left and right stereo channels. If one side is quieter or missing:
- stop the set and lower the volume before repositioning the headphones;
- confirm that left and right earpieces are worn on the labelled sides;
- check that the stereo plug is fully inserted;
- make sure the headphones sit similarly over or in both ears;
- test each alternating channel at a conservative level; and
- if available, compare with another known-working stereo headset.
Do not solve a quieter side by raising the overall volume to an uncomfortable level. Mangrove recommends headphones or an accessory with volume control because its stereo output is strong. Hearing differences, tinnitus or sound sensitivity may also influence the client’s experience and require appropriate clinical judgement or referral.
Check whether phase is creating a timing difference
When visual, tactile and auditory modalities are used together, the phase control changes the timing of the tapper and audio signals relative to the lightbar. This can make the modalities feel deliberately offset even when each component is functioning correctly.
If the concern is that the light, sound and taps do not appear simultaneous, check the phase position before treating the experience as a fault. Phase changes timing relationships; it should not be used to correct a genuinely weak or missing channel.
When to remove equipment from use
Set a component aside and contact support when:
- one side does not activate consistently;
- the signal cuts in and out;
- a plug, cable or housing is visibly damaged;
- the problem follows the same component after a careful retest; or
- the system behaves unpredictably after correct setup.
Clinical sessions are not the place for improvised electrical repairs. Use another verified modality or postpone equipment-assisted stimulation if necessary.
Document the clinical significance, not the repair log
If an uneven signal affected the session, document what the client reported, the clinically meaningful response and what was used instead. Detailed warranty or troubleshooting information can be kept separately from the clinical record.
The practical takeaway
An uneven left–right experience does not automatically mean that the equipment has failed, and it should not be given an automatic clinical interpretation. Stop, clarify the difference, check the physical setup and retest briefly at a conservative level. If the problem follows a component, remove it from use. If it follows the client’s side, respond with appropriate clinical judgement rather than trying to “balance” it by force.
This article is intended for trained practitioners and provides general information only. It does not replace product instructions, accredited EMDR training, supervision, medical or audiological assessment, or individual clinical judgement.