Is the battery current drain on the hearing aid datasheet a good estimate to give my patient? What if my patient is using wireless streaming or other advanced features?
Today’s hearing aids are essentially mini computers. They require significantly more power than the old analog hearing aids of years past. These computers analyze sound and make decisions and the processing is very sophisticated. Processing is measured in MIPS or million instructions per second. The more instructions that occur in that timeframe, the more power that is required to run the hearing aid.
The measurement for battery drain in hearing aids hasn't changed; it’s based on how much current is required to amplify a pure tone sound. So on the product data sheets you're seeing the same type of current draws today, even though real life current needs are very different. For example, take a hearing aid where the product data sheet says that the current drain is 1.5 milliamps. When the patient wears that hearing aid in background noise situations, the signal processing is going to kick in to high gear to utilize noise reduction, directional microphones, multichannel compression, feedback management and other features. In these situations, the current draw will increase substantially. And if you add in wireless audio streaming on top of that, you might see the current drain double or even triple what’s on the spec sheet.
So if you estimate battery life by looking at what’s on the data sheet you will be overestimating by quite a bit. For example, if the battery is rated at 150 milliamps, you divide by 1.5 and you’ll estimate 100 hours. However, in dynamic, real-life contexts much more current is required and the battery life will be less.