I remember when I first got my OPN, I tried the Directionality Settings and set it to Full Directional and expect it to perform like the traditional beam forming approach, but didn’t find it to aggressively block out noise behind and on the sides like it should. This Full Directional setting should be basically what the (now called) Speech Booster works, blocking sounds from the sides and behind to let you focus in front. This Full Directional setting has been available from the OPN to the OPN S to the More and the Real just the same. In the OPN and OPN S, it’s part of what Oticon calls the OpenSound Navigator. In the More and Real, it became the Spatial Balancer that’s part of the MoreSound/RealSound Intelligence (see first screenshot below).
It made me curious and I did some experiment. Usually in a Full Directional traditional beam forming setting, there’s a phenomenon where a floor noise can be heard when it’s quiet enough for you to notice. So I looked for that floor noise in the Full Directional mode in a quiet place, and sure enough I did hear it. I sat in front of a fan (to act as a noise source) on a rotating office chair and as I rotate the chair, the fan noise is attenuated when it’s behind me or on the side, and sounds normal when it’s in front of me. However, it’s not like it’s aggressively attenuated; I can still hear it, albeit not as loud as when it was in front of me. It may be that Oticon doesn’t like to do aggressive beam forming attenuation to keep things consistent with its promoted open paradigm.
But nevertheless, despite this experiment proving to me that the Full Directional mode works as intended, it still does not seem to be aggressive enough when put in real life use. When I’m in a noisy cafeteria, toggling between Open Auto and Full Directional programs didn’t seem to matter much to me.
I will offer a theory below as to why it’s effective in some cases but not in other cases. My theory is based on the fact that Oticon uses a Voice Activity Detector to detect multiple speech cues and make an exception in its MVDR beam forming strategy and void null directions attenuation where the Voice Activity Detector senses speech in the back or the sides. This may be the culprit as to why Full Directionality mode doesn’t always work aggressively (see more text in the third screenshot below that talks about it from an Oticon whitepaper). If you’re in a restaurant environment where there are speeches detected behind or to your sides, it lessens the effectiveness/aggressiveness of the Full Directionality beam forming to allow you to hear those not-in-front speeches, hence the integrity of the beam forming is compromised.
In the second screenshot below, in Figure 3, you can see that Oticon employs the 2 mics on each aid and the front mic is set to omni-directional and the back mic is set to a back-facing cardioid pattern to create a noise model to be attenuated from the omni-directional pattern. However, in Figure 4, you can see that the presence of the speaker in the rear left opens up that field a bit to allow that speaker to be heard, but effectively lessens the attenuation of the 2 cars’ noise. In theory, you would think that the Full Directional mode should disregard this rear left speaker, and only takes him/her into account if the Directionality Setting is in Neural Automatic. But apparently if Oticon doesn’t fully disregard that rear left speaker and still gives weight to his/her presence despite the Full Directional setting, then that would explain why it wouldn’t work out so well in this case. But if there are no rear or side speakers presence, but only other kinds of noises, then the Full Directionality mode may work better. So this is probably why it works sometimes and not other times for some people, and even differently for the same person in different situations.
The third screenshot below is some explanation of how Oticon makes exception to allow access to multiple speech cues. For sure initially at least in the OPN and OPN S, this feature is strongly weighted in favor of the open paradigm. But perhaps somewhere down the line in a firmware update for the More, Oticon might have decided to give favor to the Full Directionality model and give access to multiple speech cues less weight, hence the observation by some users that a firmware update seems to make the MoreSound Booster (now simply the Speech Booster) to work more effectively.
