The Bonebridge (BB) is a partially implantable active transcutaneous bone conduction hearing system manufactured by MED-EL Elektromedizinische Geräte Gesellschaft m.b.H. (MED-EL, Innsbruck, Austria).

The BB augments hearing by providing acoustic input to the inner ear via bone conduction.

In 2017 Hodgetts & Scollie introduced a new fitting algorithm called DSL-BCD. The DSL-BCD algorithm was developed especially for the characteristics of bone conduction devices (BCD). If there is a benefit on the patient level in hearing outcomes when comparing the application of DSL-BCD in comparison to DSL v5 when using the BB, was not yet investigated.

The aim of this clinical study is to show the improvement in audiological performance and subjective satisfaction with the BCI602 and SAMBA 2 audio processor in patients with conductive hearing loss compared to the unaided condition and to evaluate performance differences through application of 2 different fitting algorithms, namely DSL v5 and DSL-BCD.

1. The objective of this study was to verify the influence of different fitting procedures

2. Duration of investigation:

   Unexperienced users group: Each subject will be actively involved in the study for a period of 4-6 weeks after the first fitting of the audio-processor, 4 visits in total.

   Experienced users group: Each subject implanted for at least 3 months will be asked to be involved in the study the day of their following scheduled fitting, 1 visit in total.

   We expect the study to conclude within 3 years for study start.

3. Study design: The study is designed as a prospective two-period crossover, single-subject repeated-measures. It is intended to compare the performance with and without BB system in two fitting-configurations (A: DSL v5, B: DSL-BCD) using audiometric and subjective measures. For evaluation each subject serves as his/her own control. For experienced users only acute tests in condition A and B (order randomised, sequence AB or BA) will take place. For unexperienced users the period with each condition will be 2 to 3 weeks. From the clinical perspective no specific washout period between fitting A and B is needed to avoid a carryover effect. Heterogeneity and variability inherent to the population and their outcome measures will be recognized. By using a single-subject design, the effect of variability is minimized. The use of standardized evaluation methods assures the reliability of the data across investigational center.

4. Randomisation: To eliminate the sequence effect, we performed a block randomisation to ensure that the number of patients in each sequence (fitting with configuration A or B) is similar throughout the study.

5. Inclusion criteria:

   • 18 years of age or older
   • Unilateral and/or bilateral CHL/MHL in the device indication range
   • Implanted with a BCI602 device
   • Willingness and ability to use the hearing system and to perform all tests required for the study
   • Signed, and dated informed consent before the start of any study specific procedure
   • Native speaker 5.1. Exclusion criteria: A patient with/is
   • Profound unilateral sensorineural hearing loss, often termed Single Sided deafness (SSD)
   • retrocochlear, or central auditory disorders
   • any physical, psychological, or emotional disorder that would interfere with the ability to perform on test and rehabilitation procedures
   • fluctuating hearing loss
   • subjects who do not meet one or more of the above mentioned inclusion criteria are excluded from the study

6. Fitting:

Fitting condition A: Fitted on study audioprocessor: DSL v5, Acclimatization Level - 100%, First Fit Fitting condition B: Fitted on study audioprocessor: simulated DSL-BCD, simulated on the basis of DSLv5 with adjustments to reach the DSL-BCD Only used in the experienced user group: Fitting condition C: Patients own fitting, with adjustments for best fit, fitted on patients own audioprocessor

7. Study procedure:

Test intervals Prospective design: Subjects will be evaluated in four intervals.

1. st Session The first session takes place before surgery.
2. nd Session The 2nd session will take place at activation of the Bonebridge hearing system.
3. rd Session The 3rd session will take place after 2-3 weeks using the Bonebridge in the first fitting condition.
4. th Session The 4th session will take place after 2-3 weeks using the Bonebridge in the second fitting condition.

Retrospective design: Subjects will be evaluated in one interval.

1. st Session The only session takes place the day of the next scheduled fitting (at least 3 months later their first fitting). Patient will be evaluated with their current fitting (DSL v5), and the new fitting condition (DSL-BCD).

   The 1st session comprises the following tests:

   o unaided: Speech and Spatial Questionnaire (SSQ12) / Abbreviated Profile of Hearing Aid Benefit (APHAB)

   o Air conduction/Bone conduction under headphone, bilaterally

   o Sound field tone audiometry with warble tone in unaided condition

   • Sound field speech in quiet testin unaided condition
   • Sound field speech in noise in unaided condition

   The 2nd session (acute measurements) comprises the following tests:

   o BC threshold measurement, bilaterally

   o Sound field tone audiometry with warble tone in aided condition, condition A & B*

   o Sound field speech in quiet test in aided condition, condition A & B*

   o Sound field speech in noise in aided condition, condition A & B*

   o Preference A or B questionnaire

   o SAMBA 2 will be handed out with the fitting condition according to the randomization plan * If the randomization plan provides the patient with fitting condition B for the first 2-3 weeks, then condition B will be measured first in all acute sound field measurements at visit 2.

   The 3rd session (after 2-3 weeks of use) comprises the following tests:

   o Optional: BC threshold measurement, bilaterally

   o Aided: questionnaires SSQ12 / APHAB

   o Wearing time will be noted

   • Sound field tone audiometry with warble tone in aided condition , unaided & condition A*
   • Sound field speech in quiet test in aided condition, unaided & condition A*
   • Sound field speech in noise in aided condition, unaided & condition A*
   • SAMBA 2 will be handed out with the fitting condition according to the randomization plan

   The 4th session (after another 2-3 weeks of use) comprises the following tests:

   o Aided: questionnaires SSQ12 / APHAB

   • Wearing time will be noted

   • Sound field tone audiometry with warble tone in aided condition, condition B* & acute in condition A

   • Sound field speech in quiet test in aided condition, condition B* & acute in condition A

   • Sound field speech in noise in aided condition, condition B* & acute in condition A

   • Preference A or B questionnaire

   • Release of the patient from the study followed by personalized fitting of BB for the patient

     8. Data Management: The data manager will have the following duties and assure: Data anonymity, data management and reporting of data capture, follow conclusions set out in the study protocol and can be reliably drawn from the database. Concerns are identified and reported accurately. Creates a database, validates a database, documents data received. Performs database entry and processing, validation of entered data, data entry errors, and operates database security.

   Available data from patients who dropped out of the study at a certain time point or who are lost to follow-up will be used for analysis. Source data will be verified by the investigator.

   Data of participants will be pseudonymised for data handling and analysis and anonymised for publication.

9. Statistical Analysis Descriptive statistics: To be used to report demographic (e.g. age and gender) and baseline characteristics (e.g. aetiologies). Quantitative data will be presented as mean, standard deviation and range (minimum and maximum); qualitative data as in questionnaires will be presented as absolute and relative frequencies and if appropriate as graphs. Parametric Student's t-tests or nonparametric Wilcoxon signed rank tests will be performed, depending on the data distribution. Kolmogorov-Smirnov test will be used to check for data distribution.Two-period crossover data analysis: General Linear Models with "time" (visit 3 vs. visit 4) and "treatment" (fitting A vs. fitting B) as fixed factors will be used to analyze the time-by-treatment interaction for each tested hearing outcomes. Additionally, to verify the assumption that there is no sequence effect, the mean of the dependent variables (e.g. speech test outcomes, sound field thresholds) will be compared between the AB (difference between B and A) and BA (difference between A and B) sequences.

Handling of missing data: Missing data will not be replaced but treated as "missing" values. Statistical significance will be set to p<0.05. SPSS software will be used for all analyses. Graphs will be created in Microsoft Office Excel.

Inclusion Criteria:

• 18 years of age or older
• Unilateral and/or bilateral conductive or mixed hearing loss (CHL/MHL) in indication range.
• Implanted with a BCI602 device.
• Willingness and ability to use the hearing system and to perform all tests required for the study
• Signed, and dated informed consent before the start of any study specific procedure
• Native speaker

Exclusion Criteria:

• Profound unilateral sensorineural hearing loss, often termed Single sided deafness (SSD)
• Retrocochlear, or central auditory disorders
• Any physical, psychological, or emotional disorder that would interfere with the ability to perform on test and rehabilitation procedures
• Subjects who do not meet one or more of the above mentioned inclusion criteria are excluded from the study.
• Fluctuating hearing loss.