You’re correct in saying that the OPN 1 is more suitable for hearing difficulties in noisy environments. If you look at the comparison table below between the 3 models, the 4 parameters that I deem most important for speech understanding in noisy or complex environment are: Balancing power effect, Max noise removal value, Spatial Sound LX and Speech Guard LX. You can see how superior the OPN 1 is in these 4 parameters compared to the 2 and the 3.
The Balance power effect does noise reduction of well placed noise sources in between speech sources using a directionality system. See picture below that demonstrates this. The OPN 2 has only 50% effectiveness compared to the OPN 1 on this.
After the Balance module does its noise attenuation of well placed noise sources as seen above, the balanced signal is then fed into a secondary noise cleaner called the Noise Removal module which reduces the remaining residual noise that the Balance module could not clean up, like diffused noise or a noise source directly behind the target talker.
The picture below shows how the Noise Removal module detects and does its attenuation of the noise. Within that sentence spoken by the target talker “Pain the socket in the wall duti green”, the Noise Removal module has the ability to look in 16 separate frequency bands and compared the noise “model” against the speech quickly enough (10ms interval) inside each of the 16 frequency bands to “see” how the speech looks different than the noise model to know how to remove the noise and leave the speech alone. The amount of noise removal applied is how the OPN 1 is different than the OPN 2. In the table below, the amount of noise removal is represented by the black line on the top, the speech is the pink area, and the noise removed is the dark gray area. The light gray area around the pink speech is the remaining noise not removed While the OPN 1 can remove up to a maximum of 9dB (most of the dark grey noise illustrated here), the OPN 2 is limited to remove only up to 5dB maximum. So a lot (maybe half?) of the dark grey noise shown in the picture below still remains if the OPN 2 is used.
Speech Guard LX is basically the WDRC (Wide Dynamic Range Compression) strategy from Oticon that uses fast adaptive compression to help preserve sound quality and speech details in noisy complex environments. Compression is used to reign in large changes in sound levels to fit the more dynamic sounds well into the reduced listening dynamic range of the patient. The less effective WDRC is made out to be, the less clarity and less details of the speech it preserves, making it harder for the user to understand speech, especially in noise.
Spatial Sound LX: the OPN 1 here has 4 estimators while the OPN 2 has only 2 estimators. Spatial Sound LX basically helps provide a more precise spatial awareness to help users identify where sound is coming from. In the event of multiple speakers (like in a noise restaurant with tables/people around you), the listener will be presented with all speech information from these multiple speakers by the OPN. It’s actually better for speech understanding to have clear and precise and complete information from all speakers to help the brain hearing have an easier time recognize and differentiate the multiple speech cues to separate the target speaker out from other undesired speakers and focus on the target speaker only. The spatial arrangement of these speakers is one of the very important cues to help the brain hearing do a better job of separating them out. So in this situation, it’s not noise reduction done directly by the OPN per se, but it’s noise reduction done by the brain hearing instead, with the indirect assistance by the OPN by giving the brain hearing the best spatial arrangement of the speeches that it can deliver.
By the way, if you’re overwhelmed in the cafeteria, don’t turn of your trial OPNs. Just turn the volume down to a more comfortable level. And over time, turn it up slowly until you reach the default level. It may take you up to a month to become adjusted enough to it. That’s what happened to me on my first day with the OPN 1s at work in the cafeteria. I panicked and called my audi to set a new appointment to reduce the overall default volume level right away and she reminded me that I do have volume buttons on the OPNs and that they’re my best friends in those situations. There’s also an Automatic Adaptation Manager available where your audi can set you up with 3 steps of volume from low to higher to normal, and the duration of the steps can be adjusted to one month each or whatever is available. But I find it better just to use your volume buttons to achieve the same thing anyway. That way you can adjust at your own pace.
Normally I would suggest the OPN 1 over the 2 and 3 in light of their key differentiation being in the speech enhancement area, which is the holy grail of the hearing aid industry, and the main thing in my opinion that makes the OPN the premium and revolutionary aid that it is. BUT, if the price of the OPN 2 is almost half of the price of the OPN 1 in Japan like you said it is, that alone can be a huge justification in going with the OPN 2. You’ll just have to consider whether you are in noisy and complex listening environments often enough day in and day out that you really need the max performance of the OPN 1 or not and decide for yourself. I think the most effective thing, if possible, is to trial both of them for yourself. Only you can decide after trialing them in your own environments. Nobody else can tell you otherwise.
