To begin with, allow me to define what is a hearing aid: It’s a device that amplifies the sound of the surrounding for someone who suffers from hearing loss.
Therefore, All hearing aids got the following
Gets the sounds and voices from the surrounding
Amplifies the signals it gets from the microphone. It can be analog or digital and it can be fairly simple or extremely complicated.
Transfers the amplified sounds to the inner ear so the user can hear them
For the whole thing to work.
The main part that makes the devices different in how they work is the electronics.
The audiologist defines to the manufacturer your specific needs and the hearing device is built accordingly. Sometimes, the audiologist can set the device on his own with some small trim buttons on the device. After you get the device, you can play around a bit with the volume but that’s about it. You don’t really see these devices any longer.
On this kind of devices, the audiologist can define few listening programs. Each program can help you in a different scenario. For instance, Concert, room full of people, restaurant and so on. They connect the device to a computer using some cable, configure it and disconnect the cable. This way, they trim it while you are actually using it. Once you’re home, using the device, you can switch between the programs with some button on the hearing aids or with a dedicated remote control device they give you with the hearing aid.
To begin with, the digital devices translate the sounds to binary bits and bytes, that rule the digital world. This enables manipulating the signals as you wish. You can do stuff like:
With all these great features, you can get programs that really fit your lifestyle. Every program can be tailor made for a real life scenario. Some devices automatically switch between the programs. Your hearing aid recognize the surrounding and act accordingly.
All digital devices got the same concept but they defer in the details. They all got this digital circuit that does all the magic I mentioned above. But every brand got its own technology. They all got new devices that use improved technology every now and then.
The basic principal of how hearing aids work is pretty much the same for all device sizes. BTE, ITE, CIC, Open ear (AKA open fit). The very same electronic device can be used for all those devices. The largest BTE can have either the leading technology or the oldest analog circuit. This goes for the smallest CIC device too. It can also have the best technology or the oldest technology. There is no correlation between the device size and the technology it uses.