Hearing Aid Signal Processing Comparative Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Hearing Aid Signal Processing Comparative Study (NCT04839289), a randomized na study. The primary outcome is Standardized Validated Questionnaire Measuring Hearing Aid Sound Quality for First Study Set Worn, i.e. Study Set A for Arm A-B-A and Study Set B for Arm B-A-B.

2. Clinical Question

3. Trial Design

This was a randomized, single-masked, crossover study of two receiver-in-canal hearing instruments. The record identifies the manufacturers as A and B. It describes two sequences: A-B-A and B-A-B. Participants in the first sequence wore instrument A, then instrument B, then instrument A again; participants in the second sequence wore instrument B, then instrument A, then instrument B again. The brief summary describes three home trials of approximately 10 days each.

The primary outcome concerns only the first home trial. At its end, identified as Day 10 of the study, participants rated the first set of hearing aids they had worn. Thus, the reported primary means compare the first-period ratings associated with the two randomized sequences: instrument A for the A-B-A sequence and instrument B for the B-A-B sequence. Although the overall study used a crossover structure, this endpoint is not itself a comparison of each participant’s ratings after using both instruments. Results from later trial periods are not included in the posted primary outcome figures described in the registry record.

The registry lists 27 enrolled participants. The primary outcome results report 17 participants in the A-B-A group and 9 in the B-A-B group. The reason the reported group counts do not account for every enrolled participant is not reported in the registry record. The record gives a start date of 2021-07-01, a primary completion date of 2021-08-31, and a completed status.

The record identifies the study as randomized and single-masked, but who was masked is not reported in the registry record. Further details about sequence generation, allocation concealment, conduct of masking, adherence, or deviations from the assigned order are not reported. The study summary says participants were asked to give investigators qualitative feedback about device performance and preference. The primary outcome, however, is reported as a numerical questionnaire score. The registry does not describe how qualitative feedback was analyzed.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants who were fit with first set of hearing aids for first home trial. For arm A-B-A, the outcomes will measure hearing aid A, and for arm B-A-B, the outcomes will measure hearing aid B

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Standardized Validated Questionnaire Measuring Hearing Aid Sound Quality for First Study Set Worn, i.e. Study Set A for Arm A-B-A and Study Set B for Arm B-A-B, measured over End of home trial 1 (Day 10 of study).

The primary endpoint is a score from a standardized validated questionnaire measuring perceived hearing-aid sound quality and hearing performance. The registry describes a Likert scale from 1 to 10: a score of 1 corresponds to the worst performance or sound quality, and a score of 10 to the best. The measure is reported as a mean with a standard deviation. The assessment took place at the end of home trial 1, identified as Day 10 of the study.

Patient ratings are relevant to this study’s stated focus on perceptions of hearing instruments. A questionnaire turns subjective responses into a score that can be summarized across participants, while retaining the fact that the underlying assessment is a personal rating rather than an objective measure of hearing function. A mean describes the group’s average score; a standard deviation describes how spread out the individual scores are around that average. Neither statistic, by itself, describes the full range of responses or explains why participants gave particular ratings.

The endpoint is tied to the first instrument worn, rather than to a later period after both instruments had been tried. Participants in the A-B-A sequence rated instrument A for this outcome, while participants in the B-A-B sequence rated instrument B. The registry does not report the questionnaire’s item content, scoring rules beyond the stated scale, or evidence about how the score behaves in this study population.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: each participant contributes a numerical questionnaire score, and the registry reports a mean and standard deviation for each sequence. The mean is the arithmetic average of the observed scores in a group. It provides a compact description of the group’s central score, but it does not show whether responses were clustered near the average or distributed across the scale. The standard deviation describes dispersion around the mean. A larger standard deviation indicates more variation among the observed scores, but it does not identify the shape of that variation or explain its source.

For the A-B-A sequence, the registry reports 17 participants, a mean of 7.16, and a standard deviation of 0.46. For the B-A-B sequence, it reports 9 participants, a mean of 7.12, and a standard deviation of 0.85. These are summary statistics, not participant-level observations. Without participant-level data, it is not possible to inspect the score distribution, identify unusual values, or determine whether different response patterns are hidden behind similar means. No confidence intervals or test results for the primary comparison are reported in the registry record.

What does a confidence interval add?

General statistical explanation: A confidence interval gives a range of values compatible with the observed data under a stated statistical procedure. It communicates uncertainty in an estimate, whereas a standard deviation describes variation among individual observations. A confidence interval for a mean would depend on the sample size and the variability of the scores, as well as the method used to construct it. The registry does not report a confidence interval for these primary group means, so their precision cannot be fully assessed from the posted summaries alone.

What would a comparison test answer?

General statistical explanation: A statistical test evaluates how compatible observed data are with a specified null hypothesis, given an analysis model and its assumptions. A p-value is not the probability that the null hypothesis is true, nor does it measure the size or practical importance of an effect. A confidence interval and an estimate of the contrast are generally more informative for understanding magnitude and precision. The registry does not report a p-value, a confidence interval, or a formal primary contrast, so no such conclusion can be drawn from the posted means.

The crossover structure requires careful attention to which period the endpoint represents. A crossover analysis can use repeated observations from the same participant and account for the fact that measurements from one person are related. Such an analysis may also consider period, sequence, or possible carryover effects, depending on the study question and design. Here, the primary endpoint is explicitly the first home trial, with one first-device score assigned to each sequence group. The posted primary summaries therefore describe first-period outcomes by sequence, not a paired comparison of device ratings over all trial periods. Whether analyses of later periods were conducted, and how the crossover data were modeled, are not reported in the registry record.

Randomization is intended to make assigned groups comparable on average with respect to factors that could influence outcomes, subject to the conduct of the trial and the amount of data available. It does not ensure that groups will be identical in a particular study. The registry identifies randomized allocation, but the method used to generate or conceal the allocation is not reported. The single-masked designation also does not identify who was masked. Those details matter when interpreting subjective questionnaire scores because expectations or knowledge of device identity could influence responses, but the record does not establish whether or how such influences were controlled.

The planning assumptions described for the sample-size illustration are distinct from the trial’s observed results. The illustration uses a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation, with the effect to detect stated as a fraction of the observed effect. Those are planning assumptions, not a description of the actual allocation or analysis. The registry record does not report the trial’s own sample-size justification. A planning calculation is not observed power and does not show the probability that this completed trial detected an effect. The numerical planning estimates are not reported in the registry record.

General statistical explanation: Over-dispersion occurs when observed variation is greater than a model assumes. If a model understates variation, standard errors can be too small and confidence intervals too narrow. Conversely, a model that handles variation appropriately can give more reliable uncertainty estimates. The primary endpoint is summarized as a continuous score, but the registry does not report a fitted model, residual checks, or an assessment of distributional assumptions. It is therefore not possible to say whether over-dispersion was relevant to the analysis or how it was addressed.

For any inferential comparison, the analysis should align with the study question and the unit of randomization, and should state how missing observations and design features were handled. The registry identifies four analyses but does not describe the statistical methods for them. The method used to estimate the primary contrast, the uncertainty measure, any adjustment variables, and the analysis population are not reported in the registry record. The descriptive score summaries remain interpretable as reported, but they do not substitute for those missing analysis details.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("A-B-A", "B-A-B")
n   <- c(17, 9)
m   <- c(7.16, 7.12)
sp  <- c(0.46, 0.85)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  A-B-A  17  7.160  0.460  6.923  7.397
CARM  B-A-B  9  7.120  0.850  6.467  7.773

11. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures and four analyses, with zero secondary outcomes having posted results. The record does not explain how the analyses relate to the outcome measures, which results were designated primary or secondary beyond the stated primary outcome, or whether any adjustment for multiple testing was planned or performed. A multiplicity strategy is not reported in the registry record.

General statistical explanation: When several outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase if each test is interpreted in isolation. A prespecified hierarchy, adjustment procedure, or clear separation of confirmatory and exploratory analyses can help readers interpret multiple results. Because the registry does not describe such a strategy, the role of multiplicity in the analysis cannot be assessed from the record.

Missing-data handling is also not reported. The primary outcome group counts are 17 and 9, while overall enrollment is 27; the reason for the difference is not reported in the registry record. These counts alone do not establish how many questionnaires were missing, whether any participants were excluded, or why the reported outcome population differs from enrollment. The registry does not say whether incomplete responses were imputed, whether analyses used complete cases, or whether sensitivity analyses were conducted.

The analysis population is not reported. It is therefore unclear whether the posted summaries include all randomized participants with available scores, a subset defined by protocol adherence, or another group. The registry also does not report how sequence deviations, withdrawals, or incomplete home trials were handled. These omissions limit assessment of how representative the reported scores are of all enrolled participants and whether the analysis followed the randomized assignment.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry reports safety figures separately for each instrument group. For Manufacturer A, 27 participants are listed as at risk for serious adverse events and 27 as at risk for other adverse events; the corresponding affected counts are zero and zero. For Manufacturer B, 27 participants are listed as at risk for serious adverse events and 27 as at risk for other adverse events; the affected counts are also zero and zero. The death count is zero in both groups.

These entries mean that the registry reports no serious adverse events, no other adverse events, and no deaths in the displayed groups. They should be read as registry-reported counts, not as evidence that an event was impossible or that no event could occur outside the recorded reporting period. The record does not provide event terms for serious adverse events, follow-up details specific to safety, or further explanation of how the at-risk counts were defined.

Because the study uses a crossover design, a participant may be represented in the safety reporting for both instruments. The group counts should not automatically be read as two independent sets of participants. The registry does not give participant-level safety data or explain the counting approach in greater detail. These figures describe the posted adverse-event record; they do not establish a broader safety conclusion.

13. What the Result Does, and Does Not, Mean

The primary results describe participants’ average questionnaire ratings after the first home trial. The A-B-A sequence, whose first device was Manufacturer A’s instrument, has a reported mean of 7.16 and standard deviation of 0.46 among 17 participants. The B-A-B sequence, whose first device was Manufacturer B’s instrument, has a reported mean of 7.12 and standard deviation of 0.85 among 9 participants. The scores use a scale from 1, the worst rating, to 10, the best.

These summaries show the reported average scores and the spread of scores in the two sequence groups. They do not show an inferential estimate of the difference between instruments. The registry does not report a confidence interval or p-value for the primary comparison, so the precision and statistical compatibility of possible differences cannot be evaluated from these results. The record also does not provide a threshold for interpreting the size of a score contrast as important to participants.

The outcome is limited to the first device used. Although participants were assigned to crossover sequences involving both instruments, the primary endpoint does not compare both device ratings within each participant. Nor do the primary results described in the record establish what happened in the later home trials. They should not be interpreted as a complete analysis of all periods of the crossover design.

The descriptive results do not establish that the instruments are equivalent, that one is superior, or that their perceived performance is meaningfully different. Establishing equivalence would require a prespecified margin and an analysis designed to evaluate that margin; neither is reported in the registry record. A lack of inferential results is also not proof that there is no difference. The results support only a cautious description of first-trial questionnaire scores in the reported groups.

The study summary says participants were asked to provide qualitative feedback about performance and preference. The primary posted outcome is a numerical questionnaire score. Qualitative findings and preference results are not reported in the registry record, so the score summaries should not be treated as a complete account of participants’ views.

14. Why This Trial Matters Statistically

This study illustrates why trial design and outcome timing matter when interpreting a crossover study. The sequence names indicate that participants were scheduled to use both instruments, but the primary outcome concerns the first home trial only. For that endpoint, each randomized sequence contributes a rating for a different first-worn instrument. Recognizing this distinction prevents a first-period group comparison from being mistaken for a paired, within-participant comparison across all periods.

The study also makes the difference between a point estimate and its uncertainty visible. The reported means, 7.16 and 7.12, describe the average scores in their respective groups. The standard deviations, 0.46 and 0.85, describe variation among participant scores. Neither statistic alone supplies the uncertainty around a contrast between groups. Without an inferential estimate or confidence interval, a reader cannot determine how precisely a difference was estimated from the posted record.

Subjective outcomes can be important to a study focused on patient perception, but they also make clear reporting of measurement and masking especially useful. The registry identifies a standardized validated questionnaire and defines the score direction and scale. It does not report the questionnaire items, who was masked, or how the questionnaire data were analyzed. Those details would help readers judge how ratings were collected and how the numerical summaries relate to the broader reported aim of gathering qualitative feedback.

Finally, the posted record distinguishes trial enrollment from the outcome group counts without explaining the difference. It also lists multiple outcome measures and analyses without describing a multiplicity strategy or missing-data approach. These are not reasons to dismiss the reported descriptive summaries. They are reasons to limit conclusions to what those summaries directly describe and to recognize which elements of the statistical analysis remain undocumented.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary outcome is measured after the first home trial, even though the study is described as a crossover. The posted endpoint therefore represents ratings of the first device worn in each randomized sequence, not a within-person contrast using both instruments. The registry does not provide primary results from later trial periods, so the results cannot characterize the full sequence of device experiences.

Outcome group sizes are reported as 17 for A-B-A and 9 for B-A-B, while enrollment is 27. The reason for this difference is not reported in the registry record. No information is given about missing questionnaires, withdrawals, eligibility for the analysis, or deviations from the assigned sequence. Without those details, the representativeness of the posted analysis groups is uncertain.

The registry reports group means and standard deviations but no confidence interval, p-value, or formal estimate of the primary contrast. It does not state a threshold for a meaningful score difference. The record therefore supports description but does not allow assessment of the precision or inferential strength of the comparison. It also does not report an equivalence margin or an equivalence analysis.

Further limitations are that the identity of the masked party, allocation procedures, questionnaire items, scoring details beyond the stated scale, and analysis methods are not reported. The registry lists multiple outcomes and analyses but does not report a multiplicity plan. It also does not describe missing-data methods, the analysis population, or any adjustment for period, sequence, or other factors. The qualitative feedback and preference information described in the study summary are not reported as results in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Hearing Aid Signal Processing Comparative Study — NCT04839289.
• Registry record last updated 2023-03-22; status last verified 2021-07.
• Results first posted 2023-03-22.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The completed study, NCT04839289, enrolled 27 participants with sensorineural hearing loss. It was randomized, single-masked, and used an A-B-A or B-A-B crossover sequence to compare receiver-in-canal hearing instruments from Manufacturer A and Manufacturer B. The registry reports a start date of 2021-07-01 and a primary completion date of 2021-08-31.

The primary outcome was a standardized validated questionnaire score for perceived hearing performance and sound quality, assessed at the end of home trial 1, identified as Day 10. The A-B-A group had 17 participants, a mean score of 7.16, and a standard deviation of 0.46. The B-A-B group had 9 participants, a mean of 7.12, and a standard deviation of 0.85. The registry does not report a confidence interval or p-value for this comparison. It lists six outcome measures and four analyses, with zero secondary outcomes having posted results.

The safety record lists zero serious adverse events, zero other adverse events, and zero deaths for both instrument groups. Details about missing data, the analysis population, statistical methods, and the reason for the difference between enrollment and outcome group counts are not reported in the registry record.