Randomised Study of Web-Based Auditory Training With Varying Perceptual and Cognitive Demands on Training Gains and Generalised Speech, Cognitive, and Communication Outcomes

Performance on the trained PLUS tasks (phonemic discrimination and competing speech) will be measured across the 10 training sessions. Each task uses an adaptive procedure to generate a threshold that reflects the level at which participants correctly identify the target speech information 50% of the time. For phonemic discrimination, this is the smallest contrast between speech sounds that can be reliably distinguished. For competing speech, this is the signal-to-noise ratio needed to understand the target talker. Thresholds from each session indicate learning and changes in trained task performance.

This is a 2-back designed to assess how well participants can keep track of and update information in WM. Letters (A-Z) are presented one at a time, and participants indicate whether the current letter matches the one shown two positions earlier. Each block contains 120 trials: 30 targets (2-back matches) and 90 non-targets. The first two trials are always non-targets. Two distinct versions of the task, each with a different predefined letter sequence, are used to avoid repetition; participants complete one version at pre-training and the alternate version at post-training. Each letter is displayed for 1000 ms within a 2500-ms trial window. Responses are made via keyboard or touchscreen. Accuracy is calculated as correct identification of targets and correct rejection of non-targets, with higher scores indicating better working-memory updating.

This task measures how well participants respond to a central target while ignoring surrounding distractor items. On each trial, a row of fish appears and participants indicate the direction of the middle fish. One practice block (4 trials) and one test block (12 trials) are completed. Each trial begins with a fixation cross (500 ms in practice; 400, 800, or 1200 ms in test trials). Distractor fish then appear for 1150 ms, with the target fish appearing 200 ms later and remaining visible for 750 ms. Participants respond using 'Q'/'P' keys or touchscreen buttons. Feedback is shown for 500 ms. Trials are easier when distractors point the same way as the target and harder when they point the opposite way. Performance is based on response speed and accuracy, with higher scores indicating better ability to manage distracting information.

Participants complete two tasks at the same time: remembering a sequence of five visually presented digits and repeating spoken words in background noise. Each trial begins with a five-digit string shown for five seconds. Participants then hear five monosyllabic words (AB Isophonemic lists) presented in 0 dB ICRA multitalker babble. Words appear one per screen, beginning 250 ms after screen onset, with the noise continuing for 3000 ms. After typing each word, the next screen appears. Once all five words are entered, participants recall the original five digits. There are four trials in total, with trial order randomised. Scores range from 0-20 for correctly repeated words and 0-20 for correctly recalled digits. Two distinct digit-word lists are used: List 1 is completed in Week 1 (pre-training) and List 2 in Week 2 (post-training).

This test is designed to assess how well participants can switch their thinking or adapt to new rules and situations. Participants are shown cards that vary in colour, shape, and number and are asked to match a target card to one of four cards displayed above it. The matching rule may relate to colour, shape, or number, but the rule is not given and must be inferred from feedback. Correct responses trigger a green thumbs-up icon and incorrect responses a grey thumbs-down icon, shown for 500 ms. Cards remain on screen until a response is made and feedback is displayed. The rule changes periodically, requiring participants to adjust their choices based on the feedback they receive. Performance is scored by the number of correct sorts and the frequency of perseverative errors, defined as continuing to use a previous rule despite negative feedback. Higher scores indicate better performance on the task.

Participants are asked to rate their perceived hearing disability (difficulty) and the associated handicap (importance of that difficulty) across four standard listening situations: conversation with one person in quiet, conversation in noise, group conversation, and TV listening. Each is rated on a five-point scale (1 = no difficulty / no importance, 5 = cannot manage at all / very important). Separate mean scores are calculated for Disability and Handicap and expressed as percentages, with higher scores reflecting greater perceived difficulty or handicap. Participants who wear a hearing aid(s) will be asked to complete this questionnaire based on how they hear with their hearing aid(s).

This is a validated self-report instrument designed to measure the perceived psychosocial impact of hearing loss on an individual's daily functioning. The questionnaire comprises 18 items addressing various hearing-related difficulties and emotional responses. Participants respond to each item using a three-point scale: "Yes," "Sometimes," or "No," which are scored 4, 2, and 0 points respectively. The total score ranges from 0 to 72, with higher scores reflecting greater self-perceived hearing handicap. This scoring approach enables the quantification of the degree to which hearing loss affects communication and quality of life, facilitating both clinical assessment and research measurement of hearing-related disability. Participants who wear a hearing aid(s) will be asked to complete this questionnaire based on how they hear with their hearing aid(s).

The Social Participation Restrictions Questionnaire (SPaRQ) is a 19-item, self-report instrument developed to assess the impact of hearing loss on social participation in adults. It comprises two subscales: the 9-item 'Social Behaviors' subscale, which evaluates difficulties in performing social actions due to hearing loss, and the 10-item 'Social Perceptions' subscale, which assesses negative thoughts and feelings experienced in social contexts related to hearing loss. Participants respond to each item using a five-point Likert scale ranging from 'Strongly disagree' to 'Strongly agree'. The total score is the sum of all item scores, with higher scores indicating greater perceived restrictions in social participation. Participants who wear a hearing aid(s) will be asked to complete this questionnaire based on how they hear with their hearing aid(s).

Participants hear triplets of monosyllabic digits (0-9, excluding 7) presented against steady speech-shaped noise in a version of the task rebuilt by the research team in Gorilla. An adaptive 2-up/1-down procedure adjusts the signal-to-noise ratio (SNR) to estimate the speech reception threshold (SRT). The test begins with two fixed trials at 0 dB SNR, then uses step sizes of 8 dB at the first reversal, 4 dB at the second, and 2 dB for the remaining reversals. Exactly 40 trials are administered, with SNRs ranging from -10 to +15 dB. The final SRT is calculated as the average SNR across the last eight reversals, with more negative values indicating better speech-in-noise perception. A cut-off of -5.5 dB SNR or higher is used to identify participants with listening difficulties.