Smart and small innovative technologies behind the. Cochlear Baha 5 Sound Processor. Introduction. Mark C. Flynn, PhD

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1 Cochlear Baha 5 Smart and small innovative technologies behind the Cochlear Baha 5 Mark C. Flynn, PhD Based on user feedback, the development of the Cochlear Baha 5 Systems has focused on three key main challenges based on user feedback; (1) a smaller and more discreet sound processor, (2) an improved hearing experience with a sound processor that adapts to the environment and (3) a simplified user interface with direct connectivity to smartphones. The solution required a total rethink of the transducer design. For the first time, a significant reduction in transducer size was achieved without a consequent reduction in performance. Building on the experience from the Baha 4, the hearing experience of the user could be further improved by an expansion of the capabilities of the Scene Classification system. Similarly, direct connection, control and personalisation through a mobile phone empowers the user to take further control of their hearing world. How to overcome these challenges is the subject of this Technology Brief. Introduction The sound processor options for users of bone conduction hearing systems have increased rapidly in recent years. Each new system delivered a considerable improvement in speech understanding in challenging listening situations as well as improving control of unwanted signals such as acoustic feedback 1-7. Building on this legacy of continuous improvement, the time was right to investigate what could be done to enhance the mechanical design of the transducer; the heart of a bone conduction sound processor. Innovation focused on reducing the harmonic distortion inherent in traditional transducer designs. Additionally, improving system efficiency and current consumption enabled smaller transducer and sound processor design. with both of these systems. Furthermore, any technological innovations must work seamlessly with the advanced signal processing systems. The development of systems with advanced signal processing capabilities, taking advantage of the latest developments in transducer design and connectivity direct to a smartphone has been the focus, with the goal of providing users with an optimal hearing experience. The aim of this Technology Brief is to highlight the most important technological innovations of the new Cochlear Baha 5. The Baha 4 Systems introduced the ability to access wireless technology through the 2.4 GHz transmission system 8. The user no longer requires expensive FM systems or inconvenient intermediate devices to access wireless technology. Importantly, for the first time it was possible to stream audio and control the sound processor through a smartphone via the Cochlear Wireless Phone Clip. Further developments would be expected from utilising the Bluetooth Smart technology to make the Baha 5 a Made for iphone hearing device. This enable the user to stream information directly from their iphone and through an app, to further personalise sound processor settings and even use capabilities such as geotagging. Importantly, today s users now have an option of either a direct connection through an abutment or a magnetic connection through the skin Therefore, the sound processor must be developed to work

2 Enabling a smaller footprint with the new BCDrive transducer technology One of the key development challenges was to meet the users demands for a smaller device without compromising on performance (either gain, MPO and/or frequency response). The electromechanical transducer is at the heart of any bone conduction sound processor and responsible for the conversion of electrical energy into mechanical (vibratory) force. Three key development goals were essential in the development of the new transducer; first, to improve sound quality, especially in the low frequencies, second, to improve efficiency and reduce power consumption requirements and third, to reduce the volume of the transducer (Figure 1). An asymmetry of motion is inherent in traditional transducer designs, which adds distortion to the mechanism. In order to be efficient, the transducer, which is coupled through a direct or magnetic connection to the skull, requires a counterweight. The counterweight is coupled via a unidirectional spring to the skull and the force of the spring is balanced by a static magnet connected to the counterweight. This requires the design to balance two different forces against each other; the force of the spring to that of the static magnet. Due to this force imbalance within the transducer, there is one movement towards the skull and another movement away from the skull, resulting in asymmetrical output and distortion, particularly in the lower frequencies. To overcome this problem, a method was developed to couple the counterweight bi-directionally. The BCDrive transducer has two springs and two static magnets balancing each other, thereby creating a symmetrical force (Figure 2). This enables equal freedom of motion in both directions, providing a symmetrical motion. The symmetry results in a clearer transmission of vibratory energy and consequently 30% less distortion 13 and less transducer wobble (Figure 3). The result is a significantly improved representation of the transmitted sound. The reduction of distortion is most apparent in the low to mid frequencies, thereby further reducing upward spread of masking. Therefore, the new symmetric transducer architecture is at least twice as efficient compared to traditional transducer architecture when transducers of equal sizes are compared 13. Improving efficiency was key to significantly reducing the transducer size. In conventional bone conduction transducers, the magnet and counterweight are separated from the snap coupling by an air gap, where the transducer contracts and expands to create vibrations. This movement is controlled by the coil that can change polarity to either attract or repel the snap coupling that is mounted on the spring. To help drive this movement, a static magnet is placed in the air gap, increasing the magnetic field from the coil. However, while increasing the force, this static magnet also increases the resistance in the transducer, limiting its efficiency. In the BCDrive transducer, there are two air gaps and symmetrically placed magnets located outside the air gaps. This reduces the resistance, making the transducer more efficient, thereby producing significantly greater force output. Through increasing efficiency, a much smaller transducer can provide the same force output as larger traditional ones. An additional benefit of a more efficient design is that the transducer requires less power. Output force level in db rel. 1µN Maximum output force level* Maximum output force level Baha 5 (OFL at 90 db SPL) Baha 4 (OFL at 90 db SPL) Figure 4: Comparison of maximum output force level between the Baha 4 Sound Processor (conventional transducer) and Baha 5 (BCDrive transducer). While traditional thinking suggests that small transducers are inherently less powerful, this new architecture has enabled the reduction in size of the transducer to 55% of the original volume (Figure 1) while at the same time also reducing current consumption by 36%. This reduction in current consumption also enables the use of a smaller battery (type 312) without compromising in daily use. The use of a smaller battery further enables a smaller and more discrete sound processor design. For the first time, a significant reduction in transducer size was achieved without a consequent reduction in performance 13 (Figure 4). Input Input sound sound level level (db) (db) Default settings in Active Gain per environment Loud noise Soft noise Speech in loud noise Speech in soft noise Quiet Signal-to-noise ratio (db) (db) Loud speech Soft speech Figure 5: Using the information from Scene Classifier II, Active Gain automatically adjusts the amplification levels to match the user s needs in different listening situations. Individualisedsed Gain Active Gain Speech understanding Figure 1: BCDrive transducer design (right) compared with traditional asymmetrical transducer design (left) demonstrating a substantial reduction of the original volume. Conventional transducer m Asymmetric output Adds distortion Magnet against spring Output force BCDrive transducer m Magnet against magnet and spring against against spring spring Output force Symmetric output Clearer sound with 30% less distortion Figure 2: Graphical representation of the relationship between the counterweight, spring, skull and sound transmission. A more symmetrical design delivers a clearer representation of sound. THD at 0.5Vrms (%) OFL Total harmonic distortion Baha 5 Transducer (n=77) Baha 4 Transducer (n=24) Figure 3: Comparison of total harmonic distortion between traditional transducer design (Baha 4 transducer) and the BCDrive design (Baha 5 transducer). Lower total harmonic distortion will lead to better sound quality. Improving the hearing experience through SmartSound iq SmartSound iq is the name of Cochlear s signal processing philosophy where the overall goal is to automatically optimise the sound experience based on scene classification to deliver a more comfortable listening experience with improved hearing performance. Building on the advanced feature set of the Baha 4 7, a number of key enhancements have been introduced. To enable improved hearing experience, the focus was to expand the capability of the Scene Classifier. The new Scene Classifier II seamlessly combines the function of three key systems (1) the directional microphone settings, (2) the degree of noise reduction and (3) the new Active Gain processing system. Active Gain processing is a system that interacts with the seven sound scenes to better match user listening preferences. While a prescription provides an excellent starting point for the amplification needed by each user, Active Gain will make adjustments based on the listening needs of the user in each sound scene independently of the overall sound level. For example, in a quiet speech situation, the user may prefer to have the gain increased to improve intelligibility (Figure 5). Gain No Active Gain Figure 6: Active Gain provides very good subjective ratings of speech understanding. Individualising the settings in Baha Fitting Software may further improve performance for a small number of users. However, in a noisy situation, some further reduction in gain might be preferred to ensure comfort. This Active Gain setting works in unison with the directionality and noise management systems to ensure that the user s listening experience is consistent. Additionally, as each person is different, the Active Gain settings can be individualised in the Baha Fitting Software for the best performance. 14 When tested on the same platform, more users preferred the sound processor when Active Gain was enabled. Importantly, 90% of users preferred the sound processor with SmartSound iq (Scene Classifier II) over the one with the previous Scene Classifier 14 (Figure 6).

3 Speech understanding Sound quality Baha 5 Baha 5 Baha 4 Baha 4 Use of a cord to access a sound from audio accessories Less advanced dongle systems stream sound to and from bulky neck-worn hardware. Cochlear 2.4 GHz wireless technology streams stereo sound directly from a wireless accessory to the sound processor. The first bone conduction platform to utilise Bluetooth Smart and Made for iphone technology that lets users stream audio and control their sound processor directly from an iphone. WIRED DONGLE 2.4 GHZ SMART Number of users Number of users Figure 7. Evolution of wireless connectivity to fourth Generation Direct to Device Connectivity. DIRECT-TO-DEVICE Figure 8: When comparing the sound processors in a blind test, 9/10 users rated the speech understanding as good for the Baha 5. Figure 9: When comparing the sound processors in a blind test, 9/10 users rated the sound quality as good when using the Baha 5. Bilateral control of sound processor settings For users of bilateral sound processors, a Control Sync feature makes operation easier. There is no longer the need to adjust each sound processor individually. Simply pressing the button on one side will automatically change the program on the contralateral sound processor. This ensures that the user has the same program on each side without the need for additional program changes or confusion between the settings in one. Direct connectivity through the iphone Increasingly, wireless connectivity and connectivity through smartphone apps has become a valuable option to the wearer of bone conduction systems. When using systems with a remote microphone the user will get improved hearing performance in challenging listening situations 8. Building on the capability provided through the Baha Control App, the Baha 5 makes use of the data communication technology pioneered by Bluetooth SIG, Bluetooth Smart, and the audio communication technology from Apple through the Made for iphone programme, to enable a direct connection between the iphone, ipad or ipod touch and the Baha 5. This enables direct connectivity, without the need for dongles or an intermediate device, Cochlear have termed fourth generation connectivity (Figure 7). In this case, the user s iphone now becomes the communication gateway. Direct streaming from the iphone to the sound processor is now possible. Here, the audio output from video calls, music and exercise apps is sent directly to the sound processor without the need of an intermediate device. For the user, this is similar to the sound processor acting like wireless headphones. For difficult listening situations, the Live Listen feature in the iphone provides the capability of using the iphone as an external microphone, thereby reducing the distance to the signal and providing an improved signal-to-noise ratio. The speaker s voice is streamed directly to the sound processor in a similar way to the Cochlear Wireless Mini Microphone. Therefore, using an external microphone can provide a large improvement in signal-to-noise ratio and consequent boost in hearing performance 8. In terms of control, the Baha 5 Smart App for iphone acts as a remote control providing control over volume level and program selection. One additional feature in the app is the possibility to personalise an existing program by adjusting the treble and bass and to link to a specific location taking advantage of the inbuilt GPS in the iphone to geotag locations. One straightforward application is to use geotagging to find the location of the sound processor. Many users, however, may appreciate the ability to geotag a specific program and/or volume control setting to a location based on previous experience. In this way, the capabilities of the iphone and the hearing device are combined to create one system, which automatically adjusts the hearing experience based on previous experiences. At all times, the user is informed through notifications from the iphone about which settings have been enabled and may adapt the setting quickly and easily if required. Intelligently combining the capability of the sound processor with the Baha 5 Smart App also enables the user to create individualised listening programs that can be stored on the iphone. In this way, the settings created by the hearing care professional are always available and not altered but the user can adjust the treble and bass of each program to create a more personalised user experience. The professional can then access these settings to learn from the user how different situations have shaped their listening preferences. In summary, the Baha 5 being a Made for iphone hearing device enables four key new capabilities. First, the ability to stream audio from the iphone, ipad or the ipod touch directly to the sound processor. Second, direct control over the sound processor from the user s iphone. Third, an improved signal-to-noise ratio by using the iphone as an external microphone. Fourth, is the use of the Geotagging function of the iphone to pre-set listening preferences based on the user s location. User experience As part of the development process, a test of ten users of a bone conduction hearing systems was conducted 14. This test compared performance between the Cochlear Baha, Baha 4 and Baha 5 sound processors. Uniquely, this test was conducted single-blind so that the users did not know what sound processor they were listening to. Across ratings of speech understanding, sound quality, artefacts, and loudness, the sound processors based on Ardium technology (Baha 4 and 5 sound processors) were rated superior to the Sound Processor. Importantly, the Baha 5 was not considered to be unacceptable or bad (Figure 8 & 9) on any measure. When it came to final selection of device preference, 7/10 users, without knowledge of the size and cosmetic benefits, preferred the Baha 5 (Figure 10). Importantly, on a further investigation of 52 users, 92% preferred the design of the Baha 5 over Baha 4 and a competing design. Therefore, users of the Baha 5 will expect excellent hearing experience across the wide range of everyday listening situations combined with significantly improved size, cosmetics and usability. Summary and conclusion The Baha 5 represents a large improvement in the hearing experience offered to users of bone conduction hearing systems 14. Through focused engineering, the transducer is more efficient with less power consumption and distortion than traditional transducer designs. In addition to sound quality improvements, this development enabled a 45% reduction in transducer size. The Scene Classifier II provides further refinements in the way that sound is treated by the sound processor and importantly, the introduction of Active Gain 70% of users preferred the Baha 5 Processor over previous over previous generations generations 0% 20% 40% 60% 80% 100% Baha 4 Baha 5 Baha 4 Sound Baha 5 Sound Processor Processor Figure 10: In a blind test, seven out of ten users chose the Baha 5 Sound Processor over the previous generations. enables further individualisation of the system to meet the needs of the user. The Active Gain feature can potentially lead to less need for the user to manually adjust the volume settings. Connectivity is further developed through Made for iphone (MFi) and the Bluetooth Smart technology. This enables the user to connect directly with an iphone, ipad or ipod touch without the need for an intermediate device. This extends the hearing experience to let the user stream audio directly from the iphone to the sound processor, control volume and programs and use the iphone as a remote microphone. For those users who wish to have additional control, the ability to further personalise settings for listening preferences and location-specific actions is also available through the Baha Smart App. Given these advances, it was pleasing to see that in user tests, the improvements in terms of reported hearing experience resulted in a clear user preference for the Baha 5 Sound Processor.

4 References 1. Flynn MC, Sadeghi A, Halvarsson G. Benefits of directional microphones and noise reduction circuits for improving Baha(R) hearing performance. Cochlear Implants Int 2011;12 Suppl 1:S Flynn MC, Hedin A, Halvarsson G, Good T, Sadeghi A. Hearing performance benefits of a programmable power Baha sound processor with a directional microphone for patients with a mixed hearing loss. Clin Exp Otorhinolaryngol. 2012;5 Suppl 1:S Flynn MC. Challenges and recent developments in sound processing for Baha. Adv Otorhinolaryngol. 2011;71: Flynn M, Norrman J. Answering today s bone conduction hearing challenges with new signal processing solutions and wireless capabilities. Cochlear Bone Anchored Solutions AB, E82778, Pfiffner F, Caversaccio MD, Kompis M. Comparisons of sound processors based on osseointegrated implants in patients with conductive or mixed hearing loss. Otol Neurotol 2011;32: Oeding K, Valente M, Kerckhoff J. Effectiveness of the directional microphone in the Baha Divino. J Am Acad Audiol 2010;21: Hedin A, Andersson J, Agat T, Hoffmann J, Flynn MC. Clinical study of the new Cochlear Baha 4. Cochlear Bone Anchored Solutions AB, E83100, Hoffmann J, Andersson J, Agat T, Hedin A, Flynn MC. Hearing benefits of the Cochlear Wireless Mini Microphone for Cochlear Baha 4 Sound Processors. Cochlear Bone Anchored Solutions AB, E83101, Wilkie MD, Chakravarthy KM, Mamais C, Temple RH. Osseointegrated hearing implant surgery using a novel hydroxyapatite-coated concave abutment design. Otolaryngol Head Neck Surg 2014;151: Clamp PJ, Briggs RJ. The Cochlear Baha 4 Attract System - design concepts, surgical technique and early clinical results. Expert Rev Med Devices. 2014: Smeds H, Van Hasselt A, Luntz M, et al. Clinical outcomes from an international multi-center clinical investigation of a new magnetic bone conduction implant system. Presented at the 13th International Conference on Cochlear Implants and Other Implantable Auditory Technologies in Munich, Germany, June Iseri M, Orhan KS, Kara A, et al. A new transcutaneous bone anchored hearing device - the Baha Attract System: the first experience in Turkey. Kulak burun bogaz ihtisas dergisi : KBB = Journal of ear, nose, and throat 2014;24: Gustafsson J. BCDrive performance vs. conv. bone conduction transducer. Cochlear Bone Anchored Solutions AB, Report No , Hedin A, Andersson J, Agat T, Hoffmann J, Björk T, Flynn M. Summary of the Cochlear Baha 5 Clinical Development. Cochlear Bone Anchored Solutions AB, Report No , 2015.

5 Manufacturer: Cochlear Bone Anchored Solutions AB Konstruktionsvägen 14, Mölnlycke, Sweden Tel: Fax: The Cochlear Baha 5 is compatible with iphone 6 Plus, iphone 6, iphone 5s, iphone 5c, iphone 5, ipad Air 2, ipad Air, ipad (4th generation), ipad mini 3, ipad mini 2, ipad mini and ipod touch (5th generation) using ios7.* or later. Ardium, Baha, Baha Divino, Baha Intenso, Baha SoftWear, BCDrive, DermaLock, Vistafix and WindShield are either trademarks or registered trademarks of Cochlear Bone Anchored Solutions AB. Cochlear, SmartSound, Hear now. And always and the elliptical logo are either trademarks or registered trademarks of Cochlear Limited. LiveListen, iphone, ipad and ipod touch are trademarks of Apple Inc., registered in the U.S. and other countries. The Bluetooth word mark and logos are registered trademarks owned by Bluetooth SIG, Inc. and any use of such marks by Cochlear Limited is under license. Cochlear Bone Anchored Solutions AB All rights reserved. APR15. Printed in Sweden