The basic difference is this;  analog technology works by converting sound into electricity by means of a transducer.  More electricity is added to the incoming signal,  then it is converted back into sound.  Digital signal processing converts the sound signal into numbers.  These numbers are rearranged by algorithms.  An algorithm is a number formula or "recipe" that manages the arrangement of numbers.  They work continously,  automatically,  and simultaneously.  They are precisely configured for better understanding and comfort in noise.  The Algorithms are then programed onto an electronic chip built into the digital hearing aid. Digital sound quality is more natural sounding than analog amplification.  It is often compared to the difference in sound quality of a CD verses a cassette tape.  A new hearing aid user that had tried both types of technology stated "I could hear better with both types,  but the digital hearing aid sounded so natural, I forgot I was wearing a hearing aid."  An experienced hearing aid user stated after wearing a new digital for the first week,  "It's a world of difference than my old hearing aid,  especially in the restaurant when we went out to eat."  From my own experience in fitting hearing aids,  the most significant benefit of digital processing is better comfort and understanding in noise.

If sound signals are analyzed and graphed,  you would see that speech has a specific pattern.  It looks like a series of short signals.  Most noises such as backround talking,  motors running,  and fans blowing,  show up as a long continous signal.  The most advanced digital hearing aids seperate the frequency range of the hearing aid into channels.  The Siemens top of the line digital hearing aid, Triano has 16 channels.  This way it can be very specific in pinpointing at what frequency the noise is in and  reducing just that ,while at the same increasing amplification where the softer speech sounds are.  The lower end digital, Music has just 2 channels, which seperates the lows from the highs.  This gives a significant advantage when the loss is less severe in the low frequencies than the high frequencies. The Prisma, Signia, and Triano, all work to give additional amplification in softer speech sounds when it detects speech occurring.  In addition when it hears noise it reduces the volume at the frequency where the noise is.  Both the Prisma 2 and Triano can do this simultaneously.

Another method to bring a higher quality of hearing in a variety of situations is multi-memories.  It is similar to having three or four circuits in one hearing aid.  Each memory is design for specific situations.  Typically, a person would have a "normal" memory for quiet backrounds and one on one conversation.  A party or restaurant memory can be programed into the hearing aid for noisy situations.  Some of the other memories you can choose from are,   traffic, telephone, speaker, music.  There is a small button located on the hearing aid that you press to change memories.  When you enter a noisy restaurant, the hearing aid doesn't just turn the volume down. It turns the volume down in the low frequencies,  maintaining the volume where the softer speech sounds are.