Question: I’m a musician/pianist. I now have a Cochlear Baha 4 Sound Processor that is bone anchored. The volume of some of the pianos I play approaches the 90db ceiling on my Baha 4 unit. I’m getting distortion from the music and it seems to be across the whole frequency range of the sound processor. No one frequency or band is worse than others. Any ideas on how to eliminate the distortion?
By the way, you can simulate what I’m hearing by overdriving your stereo speakers. One way to do that is turn the volume all the way up. Same with ear buds. That’s the kind of distortion I’m hearing. It’s not feedback. It’s clipping.
Answer: Dear Tim. Congratulations on your Baha 4 Sound Processor – as a musician you should definitely notice and appreciate the additional fidelity.
You are absolutely correct, that extra effort needs to be taken when fitting any hearing device for people with specific enjoyment of music. When we design a hearing device, we focus on speech understanding. Speech is very different to music with a dynamic range of only 30dB and a loudest sound (e.g. /a/) of around 80dBSPL. Music on the other hand, will often have more low frequency emphasis (middle C is 256Hz whereas speech carries most information around 1500Hz), a much larger dynamic range approaching 100dB and input levels often peaking above 110-115dBSPL.
This calls for three potential solutions when listening to music:
1. Dedicated Music program. Your hearing care professional can create a dedicated music program. We offer one in the Baha 4 Sound Processor. This has been tailored to music by having a flatter frequency response, linear amplification (as compression can play havoc with music) and we have turned off various speech enhancement features such as noise reduction, directional microphones and tempered the feedback cancelling algorithm so it does not become confused by musical tones. This will provide an improved listening exprience.
2. Use a connection. When listening to music use a direct audio connection or listen via the wireless accessories (e.g. Mini Mic), here you can adjust the level so that the peaks of music do not overdrive the microphones.
3. Turn your hearing device off. Depending on your hearing loss, many people will remove their hearing device when listening to music. Due to the loud peaks and low frequency emphasis music is often audible whereas speech might not be. This will also avoid overdriving the analogue/digital converter of the hearing aid “front end” which may clip sounds above around 95dBSPL. This is an unfortunate limitation in most hearing instruments.
Your hearing care professional should be able to guide you through these options.
~ Mark C. Flynn, PhD Audiologist, Cochlear Bone Anchored Solutions