Released September 25, 2015. Model A1687/A1634. Repair of this device is similar to previous generations, requiring screwdrivers and prying tools. Available as GSM or CDMA / 16, 64, or 128 GB / Silver, Gold, Space Gray, or Rose Gold options.

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Changed the back housing, now mic muffled when held to ear

Hello - I am hoping I can get some help with this issue. Mic works fine in speaker mode and voice memos are clear, but when I hold the phone to my face and the screen goes dim, the caller on the other end hears only my muffled voice. Seems to only happen when the screen dims, I can pull the phone slightly away and the sound is fine (to the other caller). I have tried turning off noise cancellation as well as putting my finger over the mic on the back of the screen, with no luck. Any ideas?

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Not really sure but it sounds like a front camera ribbon cable microphone alignment issue but if you did not disassemble that area then that shouldn't be the issue.


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It will work fine in speaker mode, because it uses a different microphone, speaker mode uses your microphone that is attached to the camera flex, so is by your ear piece near the top.

If you have changed housing, then your problem will be with the microphone at the bottom which is attached to the charging port flex, there could be a few things causing a muffled sound:

- dirt in the small hole at the bottom next to the headphone port.

- microphone not placed in properly when reassembling the charging port flex, either the microphone hasn't been placed in to its slot or you haven't put the plastic bracket back in.

- adhesive could be getting in the way of the microphone at the bottom if you have put the plastic bracket back in and the adhesive has moved, or adhesive on the mesh if you moved the mesh over.

- also check the microphone itself, if none of these work, try replacing the charging flex to rule out a faulty microphone (quite rare).


(A bit of info)

There are 4 microphones on the 6s and 6s plus.

The back camera microphone is used for noise cancellation mainly, and only ever records sound when recording video.

The front camera microphone is used mainly for speakerphone conversations and Siri dictation.

There are two microphones at the bottom, the bottom left one is used for picking up your voice, and the bottom right is used to help with noise cancellation along with the back camera microphone.

So to help with the muffled sound during a call, you need to make sure there is no dirt or adhesive blocking the way of the bottom left microphone, and make sure it is inserted correctly.


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When you performed the back housing replacement, you likely removed the two speakers located on the bottom of the housing: this step and the one after it. You could try to check that they are aligned correctly in your new casing and not dirty/oily? A little isopropyl alcohol could help clean them.

The fact that the sound is only muffled once the proximity sensor is tripped and the screen goes dim is interesting... The iPhone 6s plus has 4 microphones, one next to the front facing camera, one next to the rear facing one, and two along the bottom. Perhaps the other 2 speakers near the cameras are on when the phone isn't held up to your ear, but get turned off when the proximity sensor is tripped? Hm just speculating..

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The back camera microphone is used for noise cancellation mainly, and only ever records sound when recording video.

The front camera microphone is used mainly for speakerphone conversations and Siri dictation.

Now here's where it gets interesting, the two microphones at the bottom switch roles depending on what is being done, during a voice call, the bottom left microphone is used to collect voice information, whilst the right one deals with noise cancellation just like the back microphone, but when it comes to voice message, the microphones will swap roles.

So during a voice call he would need to make sure his bottom left microphone is clear from any dirt, adheshive or make sure it's inserted correctly.


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