Any hearing aid user knows that background noise is the bane of their hearing aids' existence. Any personal sound amplifier user knows that more volume does not mean more understanding. Why is background noise such a problem?
The struggle with background noise is that there is no specific type of noise that is always "in the background". Any noise can be background noise. In the example above, the signal noise (i.e. the important noise), would be the wife of the listener; however, there is a lot of kinds of background noise present. The heating system is making noise, the TV is making noise, and there are also three other speakers in the room that are background noise, but still speech. How can a machine pick between speech and noise when speech is all over the place?
Since the end of the 1990s, directional microphones have been the cure to this problem. Directional mics only catch the sound coming in from a single direction. In the case above, the hearing aids would be set with directional mics aiming the same way as the listener's eyes. In essence, as long as he was looking at his wife, she would be louder than the others in the room.
Most hearing aids through the 2000s had directional microphones to allow for this ability, given the needed space. The user would switch between an omni mode (hearing all 360 degrees), and a directional mode.
If the user knew when to change modes, this usually worked well, but some individuals didn't have the ability to remember the program uses, and would leave the hearing aid permanently on the omni mode, losing the ability to hear in noise, and devaluing the instrument.
While this was a fantastic option for most wearers, there was still a lingering problem. What do you do with multiple signals? Say that it's Thanksgiving Day, and instead of just talking to your wife, you're at the table with your wife, your kids, her brother, his kids, and the new grand-baby. Will directional mics work there? You'd have to anticipate the speaker before they began to talk and turn your head to face them. It probably won't work.
This has been the new goal for several manufacturers in the 2010s. How can a hearing instrument classify signal and noise without relying on just directionality? It requires very, very fast processing. Oticon, one of Nova's manufacturers, created the OPN hearing aid in the mid 2010s, which didn't just use directions, but it classified between speech and non-speech and used the volume of the speech when entering the mic to decide if the speech was signal or background noise. Following that, Signia and the other major 5 labels of hearing aid all are going to be entering 2020 with some type of classification ability, so you are no longer relying on one speaker at a time. This is often referred to as "adaptive" or automated directionality. Maybe can be changed on a smartphone without using up a "program" on the actual instrument.
Unless you truly are a homebody, any modern hearing aid wearer needs directionality of some sort. This is not something to be cheap about. It's not worth being overstimulated in noisy environments to save a few hundred bucks. If you can manage a traditional directional microphone system, just be sure your hearing aid dispenser makes it very easy for you to switch between the omni and directional modes. If you don't feel as though you can work the switch, look deeply into automated directionality. In the last ten years, this is one of the greatest steps in audiology that the industry has made, and for people that struggle with dexterity or memory, it makes things incredibly easy.
As always, discuss directional needs with your audiologist or hearing aid dispenser!