The Earswitch is a demonstrated proof-of-concept that detects the voluntary contraction of a small muscle in the ear, called the tensor tympani (TT) muscle, which can be effectively used as an input switch. The voluntary activation of the TT makes the eardrum move, and such movement can be detected using a small camera inserted into the ear canal. A previously funded NIHR 'i4i Connect' research project showed how the Earswitch may be advantageous to populations with severe neuro-disabilities, where other communication methods are limited.

This project aims to realise the EarSwitch's potential as an assistive communication device and provide supporting evidence towards regulatory approval of the medical device.

The robustness and usability of the device will be tested on participants with mild-to-moderate neuro-disabilities and healthy participants. This complements data collected from assistive technology users following the same protocol but will provide additional data to train and understand the underlying detection algorithms for the Earswitch.

The ease of which an assistive technology device can be installed and calibrated independently (without guidance from the researcher) so that it is ready to use is also an important consideration for its potential adoption. Participants will have the opportunity to interactively use the Earswitch daily at home, over a prolonged period of 4 weeks. Interviews and questionnaires will be used to gather information on usability and comfort of the device, whilst data from the interactive tasks will provide feedback of engagement and performance.

Overall, this will provide crucial insights into how viable the Earswitch is as an assistive technology device and how accurately and reliably the current detection algorithm can detect contraction of the TT muscle. This data will be analysed to inform the final design of the Earswitch ready for commercial production.

Following recruitment and screening there are a number of different stages for the trial:

1. Initial face-to-face appointment (Clinical groups 2,3, and 4)
2. At-home setup (Clinical group 1)
3. At-home testing (Clinical groups 1, 2, 3, and 4)
4. Final face-to-face appointment (Clinical groups 2, 3, and 4)

1. Initial Face-to-Face Appointment (Clinical groups 2, 3, and 4)

Participants will book an in-person appointment with PHU at Queen Alexandra Hospital.

The initial face-to-face appointment will involve six main parts:

1. Demographics
2. Self assessment of skin colour by self identification on Fitzapatrick visual scale
3. EarSwitch insertion
4. Vital sign measurements, with synchronous EarSwitch in-ear video recording
5. EarSwitch Click Distribution Analysis tasks
6. Questionnaires on insertion and data collection
7. Training for home use

This should take 60-90 minutes.

Part 1: Demographics (5 minutes) This will gather basic information about the participant including age, gender, ethnicity, self assessment of skin colour by Fitzpatrick visual scale and how long they have been aware of their ability to ear rumble (where applicable).

Part 2: EarSwitch insertion (5 minutes) The participant will select an earbud size which will be inserted into the participant's ear on the left or right ear dependent on side of personal preference. The participant will then be asked if it is comfortable or whether they would like to try a different size according to the comfort or fit of the earbud. Once the participant is happy with the size of the earbud, the EarSwitch camera module will be inserted in the earbud and the EarSwitch control box connected to the research laptop by USB-C, on which the face to face trial software is loaded and running. The experimenter will ensure that the EarSwitch camera is outputting video on the experimenters trial software on the laptop, Once this is confirmed the experimenter willadvise the user how to install the Earswitch device in their ear. The experimenter will advise the subject how to position the EarSwitch camera.so that the ear drum is visible to the device, as viewed by the experimenter and user on the trial laptop. If the subject wishes the experImenter may help with initial insertion and positioning. During this procedure, the participant will be asked to let the experimenter know if it is uncomfortable or if they wish to stop. This should be no different to putting a regular ear bud into the participant's ear. The depth, direction, and curvature of the in-ear component of the EarSwitch is adjustable and the participant will be informed how to make these adjustments to ensure best comfort while ensuring the eardrum is visible.

If earwax is obscuring the view of the video feed from the EarSwitch the subject will be offered microsuction of wax - either by research nurse trained to micro suction or audiologist available to microsuction, so that the protocol can be continued.

Part 3: Vital sign measurements (15 minutes) As part of the exploratory objectives, the participant will have their vital signs measured while the EarSwitch records video of their ear drum and ear canal. The participant will be asked to sit at rest, avoiding unnecessary talking, during this period. The following vital signs will be measured: pulse, temperature, blood pressure, respiratory rate, ECG rhythm and oxygen saturations.

Part 4: EarSwitch Click Distribution Analysis tests (25 minutes) The test software will then be run including recording in-ear videos of the participant contracting the tensor tympani (TT) muscle voluntarily in response to some tasks. The tasks will ask the participant to voluntarily contract the TT muscle in response to different stimuli when requested. These stimuli will be presented to the participant visually on a screen,. The purpose of this is to see how well the participant can voluntarily contract their TT muscle on demand, and to see how well the Earswitch can detect this.

Tasks the participants will be asked to do include:

1. Reactive task: contracting the TT muscle when a target appears. This will be repeated THREE times in succession
2. Predictive task: contracting the TT muscle at the end of a countdown. This will be repeated THREE times in succession
3. Double rumble task: contracting the TT muscle twice in quick succession (like a double click on a mouse). This will be repeated THREE times in succession
4. Consecutive rumbling: contracting the TT muscle multiple times in a row in a short period of time (for example, 3 seconds). This will be repeated THREE times in succession
5. Hold rumble: holding the TT contraction for a pre-defined amount of time (for example, 1 second). This will be repeated THREE times in succession

In addition, video of the participant's ear drum will be recorded when they perform everyday tasks to understand if the EarSwitch detects other IEMs. The everyday tasks will be selected based on the capability of the participant but will include doing whatever they wish for two minutes, the participant will be asked to raise their eyebrow, yawn, move their head, and drink some water. During all these tasks the participant will not get any immediate feedback from the system, instead it will be recording the data which will be analysed after they have finished the study.

Part 5: Questionnaires on insertion and data collection (5 minutes) Participants will remove the EarSwitch before completing questionnaires to gain feedback on the insertion of the device and the ability to ear rumble.

The researcher will also measure the physical configuration of the EarSwitch by taking three photos of the device in a jig at 90 degree angles (x,y,z axes).

The researcher will complete a study observation form to detail the researchers experience with the EarSwitch, including the ease of use, any product design observations.

Part 6: Training for home use (10 minutes) The researcher will provide the subject with the EarSwitch device used in the home testing, and instruction sheets including QR code - detailing how to access the trial software on their own device and a training schedule. If the subject has brought their own device, tablet or laptop then they will be asked to connect to the PHU Wi-Fi and follow the instructions (prompted by researcher if necessary) to access the EarSwitch online trial interface, connect the EarSwitch device to the Bluetooth or USB of their own device, tablet or laptop, and operate a demonstration interface. The researcher will train the user on aspects of the device - including configuration using application, hardware controls, charging and connection. Next, the subject will be asked to run through set up procedure which will be demonstrated by the researcher to set sensitivity and alignment of the EarSwitch device. Finally, participants will complete a questionnaire about the setup of the software.

2. At-home setup (Clinical group 1) Participants in clinical group 1 (recruited by UoB) will not attend any face-to-face assessments. Participants will complete the demographics and pre-study questionnaire online, followed by the QUEST2 questionnaire based on their current assistive technology device.

Participants will be sent the EarSwitch device to their home address via post. Instructions will be included to allow a self-guided walkthrough of the setup and installation process. Remote technical support will be on offer to participants via telephone or video call to assist them in setting up the device.

Participants will complete online questionnaires to gain feedback regarding the setup and installation process.

3. At-home testing (Clinical groups 1, 2, 3, and 4)

The at-home testing phase will involve five parts:

1. Weekly tasks that are to be completed at the start of weeks 1, 2, 3, and 4, and finally at the end of week 4 (five in total).
2. Daily tasks that are to be completed four times per week.
3. Progression phone calls
4. Post-testing questionnaires
5. Exit interview and device return (clinical group 1) The subjects will be asked to consent (or not) to push notifications as reminders to complete tasks & use the EarSwitch.

Part 1: Weekly tasks

Once a week, all participants will be asked to complete a weekly interactive click distribution analysis (CDA) task, comprising of four tasks:

• Reactive task - a target will appear after a random time period and participants are asked to ear rumble as soon as they see the target. This will be repeated ?? THREE times in succession
• Predictive task - a target will appear after a predetermined amount of time which is communicated to the participant, the participant is asked to ear rumble when the target appears. This will be repeated ?? THREE times in succession
• Double rumble - same as the reactive task, except the participant is asked to perform a double ear rumble (i.e., two in a row). This will be repeated ?? THREE times in succession
• Consecutive rumble - participants will be given a duration (e.g., 5 seconds) where they are asked to ear rumble as many times as possible consecutively.This will be repeated ?? THREE times in succession These are the same tasks as in the face-to-face appointment (minus the hold rumble task) however r these are interactive which means the EarSwitch system will be actively running allowing the participants to interact with the interface using the EarSwitch and providing participants with real-time feedback. A summary of their performance will be shown upon completion.

In all weekly tasks participants will be asked about their perceptions of ear rumbling using a quantitative online questionnaire.

In the first and final weekly tasks, participants will be asked about comfort of the EarSwitch device and usability of the system using a quantitative online questionnaire.

Part 2: Daily Tasks In addition to the weekly tasks, participants will be encouraged to use the EarSwitch device and software for approximately 10 minutes per day, four times per week (allowing for the weekly test day and two rest days).

For each daily task, the participant will be asked to complete the following:

1. One specified (of the four) interactive CDA tasks

2. Type two specified words on an interactive keyboard

3. (OPTIONAL) Play a "Dino Run" game which is a side-scrolling game featuring a dinosaur that has to jump over obstacles Part 3: Progression Phone Calls Participants will receive two phone calls from the research team during weeks 1 and 3 (exact time and day according to participant preference) to see if they require any support and to support and understand adherence to the protocol.

   Part 4: Post-testing questionnaires After the four-week period, participants will complete a set of quantitative questionnaires about their experience including their overall perception, usability, and comfort of the EarSwitch device. In addition, clinical group 1 will complete the QUEST2 based on the EarSwitch device and complete a health economic questionnaire.

   Part 5: Exit interview and device return (clinical group 1) An exit interview will be conducted with the participant to gain qualitative feedback about their experience using the EarSwitch. Arrangements to return the EarSwitch device to the University of Bath will subsequently be made.

4. Final face-to-face appointment (Clinical groups 2, 3, and 4)

Participants from clinical groups 2, 3, and 4 will finish the study with a final in-person assessment.. This will involve the same activities as the initial face-to-face appointment minus the demographics and training for home use, therefore:

1. EarSwitch insertion
2. Vital sign measurements during EarSwitch video recording
3. EarSwitch Click Distribution Analysis tasks
4. Questionnaires on insertion and data collection

Finally, participants will be asked to complete some questionnaires to understand the participant's perception of interacting with the EarSwitch, including the comfort of the device and how easy it was to use. On this final visit, participants will be required to give back their Earswitch device to the research team at PHU.

Follow up:

There will be no long-term follow-up assessment of participants.

During the 4-week testing period, the follow-up procedures are as followed:

Intermittent testing at home using the web-based interface controlled by the EarSwitch, on a weekly basis (minimum) will be encouraged by reminders (if consented) by text/email (as per patient preference).

Telephone calls during weeks 1 and at 3 weeks (approximately 20 min total per subject per call).

For all participants (Clinical groups 1, 2, 3, and 4) the following inclusion criteria will apply:

1. Aged 18 and older.

2. Able to give informed consent.

3. Access to an internet-connected device (e.g., laptop/PC/ tablet/smart phone) allowing connection to the Earswitch web based trial system.

4. Ability to operate, or have someone operate on their behalf, a web browser-based interface to respond to questionnaires.

5. Normal or corrected-to-normal vision.

6. Require the use of an assistive device (defined in Appendix….) in everyday life (Clinical group 1 only).

   For clinical groups 1, 2, and 3 the following will also apply:

7. Able to voluntarily contract the tensor tympani muscle "in isolation" by self-identification, i.e., able to rumble the ear(s) "in isolation".

   For clinical group 4 the following will also apply:

8. Unable to voluntarily contract their tensor tympani muscle in isolation by self-identification, i.e., unable to rumble the ear(s) "in isolation".

   For clinical group 1 the following will also apply:

9. Individual's must require, or benefit from, the use of an assistive device in everyday life. For example, for use with communication, environmental control and/or mobility (excluding simple mechanical devices for example manual wheelchairs/walkers and frames) and excluding hearing-aids and visual aids.

   For clinical group 2 the following will also apply:

10. Individuals must have a mild to moderate motor neurodisabilities and not require electronic assistive or communication (AAC) technology. The definition of mild to moderate motor-neurological disability is broad and will include participants with mild to moderate motor disabilities not requiring assistive technology (including MND/ Multiple Sclerosis/Parkinson's /Cerebral Palsy /Stroke / Post head injury /other rare degenerative diseases).

Exclusion criteria

The following exclusion criteria will apply:

1. Those who do not have the capacity to understand the study and consent (e.g., severe learning disabilities).
2. Inability to communicate either directly to the researcher or through a carer or communication partner and therefore inability to provide consent.
3. Contraindication to use of EarSwitch including receiving treatment for an intercurrent ear infection or experiencing ear discharge or pain.
4. Unable to view eardrum despite removal of ear-wax by ear micro-suction.

Participant data will be automatically anonymised and therefore individual participant data will not be available to other researchers.

Anonymised data will be transferred to Earswitch Ltd and analysed in the future by Earswitch Ltd for the development of more robust algorithms for detecting voluntary tensor tympani movement.

No masking will take place.