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A limitation of Spheric Speech in Loud Noise Default Microphone Settings

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SSC with directional mic results in poorer performance for speech from behind.I was reading a recent Phonak Insight which illustrated one of the disadvantages of using the default fixed directional microphone setting in the Spheric Speech in Loud Noise program: median speech recognition scores for talkers from behind was significantly worse than with Spheric Speech in noise turned off and a real ear sound microphone pattern being used, at least in this population of adolescents. I don't think it would be significantly different for adults.

If you are in a very loud situation and you need to hear people behind you, for example you're working in a kitchen with your back turned to others e.g. a working as a chef, or if you're in a wheelchair and need to hear the people behind you then you may on average perform better with real-ear sound being enabled in the Spheric Speech in Loud Noise destination in Autosense OS, or you could have a manual Spheric Speech in Loud Noise program with real ear sound as the microphone mode instead.

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Very interesting. I forget, does myPhonak expose the microphone slider in SSC? I can see the reasoning for defaulting to fixed directional - in practice that is what you'll want most of the time and it makes the 's job easier. However I'm a wheelchair user and the scenario you describe is very true also. I'll say that in my still fairly limited experience with SSC that it actually did just fine with with back and side speech. Which brings up another question: how does it interact with "motion sensor hearing"? IIRC that sets the microphone mode to Real Ear Sound if the aids detect that the wearer is moving, but does that override the microphone mode set when SSC is active?

Also interesting to see in this graph: the diminishing returns of higher SSC settings. I have E70s so I'm capped at 5 already. For kicks I mocked up my setup in Target using E90s and it only raised the default value by 1 step to 6. This backs up the idea that more aggressive denoising isn't necessarily better past a certain point.

@libc said:

Which brings up another question: how does it interact with "motion sensor hearing"? IIRC that sets the microphone mode to Real Ear Sound if the aids detect that the wearer is moving, but does that override the microphone mode set when SSC is active?

Thanks for reminding me of this. It seems to address the main concern but wasn't explicitly mentioned in the study. Motion sensor hearing activates real-ear sound or omnidirectional mode after 6 steps and spheric speech clarity keeps working on this signal, so if you're in motion this isn't going to be an issue, but if you're not walking then the narrower directionality may not work in your favour.

I'm unsure how that works if you're in a wheelchair as the motion isn't quite the same as stepping even though there's acceleration and deceleration as part of the overall movement, with more of these for a manual wheelchair than an electric one. Perhaps @Um_bongo or @Neville might know?

I’ve wondered about this too. The motion profile is different but still ought to be detectable. The accelerometer isn’t being used for too much else. I’d like to think Phonak’s engineers thought of this.

In reply to @libc

Thanks. So if you're in a wheelchair and someone is pushing you, it might be better to have spheric speech in loud noise using real ear sound or omnidirectional as the microphone input in a manual program that you can use @libc. Alternatively, you may prefer this as the default setting.

Answering my own question from earlier: myPhonak lets you adjust speech focus in Spherical mode. Interestingly and related to my other thread the slider is set to real ear sound when you go to adjust it. So it at least appears there’s a way to get that without changing the default in Target

In reply to @Bimodal_user

@Bimodal_user said:

There was whitepaper from Phonak Evidence Library (IIRC from 2024) that shows that SSC is very good omnidirectionally (although the best results were for front speakers at 0° azimuth).

https://www.phonak.com/content/dam/phonak/en/evidence-library/field-studies/PH_FieldStudyNews_SphericSpeechClarityAudiology_210x297_EN_028-2683-02_V1.00.pdf

Spheric Speech Clarity SSC any directions omnidirectional

So for wheelchair uses, an omnidirectional microphone or real ear sound + spheric speech clarity may be a better option if they don't want to use manual programs.

It'd be interesting see studies in younger children to see if there's a preference for omnidirectional + SSC given they don't reliably look at the talker.

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