TABLE 3.
A list of commonly used independent variables in hearing science, with explanatory notes, grouped into the methodological dimensions of Sources of stimuli, Environment, Context of participation, Task, and Individual
| Methodological dimension | Independent variables |
|---|---|
| Sources of stimuli | Characteristics of stimulus sources; e.g., speech/other, diversity, familiarity, continuous vs. events |
| Characteristics of stimulus materials; e.g., monotonous, dynamic, neutral, emotional | |
| For multimodal stimuli, which modalities are subjected to controlled manipulation; e.g., audio, visual, tactile | |
| How other people are represented; disembodied voice -> real people axis. Includes potential for “uncanny valley” effects | |
| Environment (presentation of stimuli) | Acoustic field; e.g., levels, SNRs, spatial fidelity, size of eventual sweet spot |
| Interaction of environment and hearing devices; degree to which the reproduced field (sound or other signal modalities) provokes the same device behavior as the real field would | |
| Incorporation of dynamic aspects; e.g., movement of sources | |
| Modalities included; e.g., visual, inertial | |
| Context of participation | Participant preparation; e.g., instructions, explanation provided for the purpose of the experiment, familiarization/training sequence |
| Semantic associations of the situation being simulated for the participant; e.g., does the participant ever take part in such a situation, does the participant have negative associations with it (“I always fail”) | |
| Motivation to take part; e.g., incentive, reimbursement, mode of recruitment | |
| Familiarity with the lab and its people and/or methods; e.g., regular “semiprofessional” participants or patients in clinical routine | |
| Psychological/physiological state at time of experiment; e.g., has the participant recently experienced a traumatic event or consumed psychoactive substances, does s/he have an important appointment later today | |
| Task | Nature of task; e.g., speech communication vs. environmental monitoring/detection |
| Nature of task if speech; e.g., repeat, recall, comprehend | |
| Complexity; e.g., single vs. multiple tasks | |
| Degree of constraint on route to task fulfillment; continuum from e.g., “press the button every time food is mentioned” to, e.g., “find out whether you have any acquaintances in common”. | |
| Exploratory movement; degree to which body/head/eye movements by the participant (a) are allowed, and (b) produce realistic changes in the stimuli | |
| Interaction; participant as observer/reporter vs. interactor | |
| Predictability; e.g., limited response options, pattern of stimuli presentations | |
| Distractors; e.g., visuals and audio unrelated to the explicit task | |
| Individual | Personality; e.g., open, agreeable, extroverted, neurotic |
| Hearing health; e.g., type, degree and configuration of hearing loss, tinnitus, hyperacusis | |
| Sensory, cognitive, motor abilities; e.g., visual acuity, working memory, balance | |
| Mental health; e.g., depressed or anxious. | |
| Competency in task language; e.g., native vs. non-native, literacy level | |
| Cultural background; e.g., ethnic, socioeconomic or religious factors affecting compliance, social desirability bias | |
| Occupation/skillsets/training; educational and skill levels and educational attainment | |
| Disease burden; e.g., frailty, multimorbidity |
The labels used for each independent variable in future tables are shown in italics.