user29714: Background
My wife is a private tutor and cannot carry on with classes due to Covid 19. Using Skype, Zoom etc is ruled out due to scheduling conflicts with schools using them. That pretty much left is with the only choice of recording videos, uploading them to cloud and sharing links with her students. Each video is typically half an hour
Set up

Room, isolated from external noise. 
Whiteboard to draw and explain. 
One Plus 7 mobile running Android 10 placed close enough and using the phone mic to capture audio. 
Post recording processing on a laptop is not possible for a bunch of reasons. We don't want to invest in recorders, mixers etc

Problem
Ceiling Fan noise. It's summer here and a fan is a must (no air-conditioning). This makes for a poor video, especially when she is facing the whiteboard.
There is no problem with the video portion, lighting etc. 
Tried and didn't work

She isn't comfortable with head phones, so I tried using Bluetooth earphones and using the Bluetooth audio instead of phone mic but it didn't work reliably. 
Android apps that claim to reduce noise. Results aren't good. 

These questions, emphasized that I should be using a good mic (since post recording processing is not possible) 

Microphone suggestions or software to avoid background noise in audio
How to reduce background noise in the video

Questions

What kind of mic and the typical characteristics of the mic I should be looking for? 
Is there any other alternative solution apart from mic? For instance, a paid Android app that can do this for sure? Or something else? 

We are on a budget and since the videos aren't meant to be high quality anyway, low cost solutions are preferred. It would be nice if someone could link a product from Amazon (India) as an example. 
PS: Lengthy question, yes, to make sure the situation is clear and hoping for a workable solution

user29714: Answering my question with a no extra cost solution using the Noise cancellation headset I had.
Using any Bluetooth headset (even supporting BT 5.0) like Crossbeats
and recording with stock camera app or with Open Camera with audio source set to external doesn't work.

Solution

I had a Bose BT2 Bluetooth headset, which I haven't used in the last 7 years and surprisingly charged up and gives me about an hour of usage time which is more than enough. I wanted to use this to improve the quality of recording since it has excellent noise cancellation. You may as well pick up any recent BT headsets of your choice and of recent vintage. Profiles supported by Bose headset are
HSP, HFP, A2DP - SNK, AVRCP

Download Bluetooth Mono Router. Blogs and YouTube videos recommend BTmono but it hasn't been updated for Android 10 and won't work. Both these apps have the same functionality - they let you play BT audio to those old headsets which only support voice calls and not media. I am not clear as to how this let's you overcome the limitations of recording but it works (someone here may have an explanation) . You can use either stock camera app or Open Camera (audio as external in settings)

In case you can't record, activate developer options and from Bluetooth settings try AVRCP 1.3 and SBC codec combination. These seem promising. In my case I used default



Permit me  a little rant about One Plus tech support with interactions over several mails. YMMV. Documenting it just in case it helps others.

They do not respond when you ask them how to record using Bluetooth.

Using wired Lavalier solutions need an extra adapter in some cases and even then no guarantees. Reason : Non standard implementation of USB C to audio adapter (Shades of wrong resistance used in early models)
. They claim on mail that TRRS is not supported since it is a third party affair and when confronted with standards do not reply



user26178: Forget an app. The truth is that a mic is, not only the best option but also an honest option. It will help the audience to focus on the content instead of making it a pain to hear.
I would go for a cable lavalier mic, there are some in amazon, and they are the cheapest alternative.
https://www.amazon.com/s?k=cellphone+microphone
The other option is a shotgun mic, but they are a bit more expensive, and normally are for outdoor usage and for interviews for example. For one person a lavalier is the best alternative.
You could also try a "hands-free" earphone with a mic. Probably your cellphone came with one already.

Why a lavalier?
The way a lavalier mic reduces the ambient noise is... It does not.
But the ratio of the proximity to your mouth, let's say 10cm or 4in to any other source of a sound, a fan, that can be 2mts away is 20 times the distance. And depending on the echo of the room, this difference could make the sound less prominent by one law that is the inverse square law that makes this difference exponential.
But if you have your camera at let's say 2m away from you, using the internal mic, and the fan is above you, the ratio of distances is probably only 1.5 times. So when you record your voice, you need to pump the volume, therefore you also pump the volume for the fan.

Hands-free is not the same as Bluetooth. There are cable options.
Regarding a blue tooth or not, I can not recommend anything. Bluetooth has the risk of having some delay, or not. If that is not important, because you are not showing the face it is ok. But this depends on the model or brand. I suppose if you buy one Bluetooth hands-free for some brand it would recognize that device.
Cable or Bluetooth is just a way to connect a device. That is up to you and you need to make some homework to see if the device fits your phone.
But normally a lavalier mic is expected to have better sound quality than mic on a hands-free device. Of course, depends on the brand.
Some cable lavalier mics need batteries, make sure to buy some extra. Also, check the length of the cable.
You could add some cable extension, but that is not recommended because you could add electronic noise into the signal, but you could try. The not so cheap option is a lavalier with a UHF transmitter.

29714: <p><strong>Background</strong></p>

<p>My wife is a private tutor and cannot carry on with classes due to Covid 19. Using Skype, Zoom etc is ruled out due to scheduling conflicts with schools using them. That pretty much left is with the only choice of recording videos, uploading them to cloud and sharing links with her students. Each video is typically half an hour</p>

<p><strong>Set up</strong></p>

<ul>
<li><p>Room, isolated from external noise. </p></li>
<li><p>Whiteboard to draw and explain. </p></li>
<li><p>One Plus 7 mobile running Android 10 placed close enough and using the phone mic to capture audio. </p></li>
<li><p>Post recording processing on a laptop is not possible for a bunch of reasons. We don't want to invest in recorders, mixers etc</p></li>
</ul>

<p><strong>Problem</strong></p>

<p><strong>Ceiling Fan noise</strong>. It's summer here and a fan is a <em>must</em> (no air-conditioning). This makes for a poor video, especially when she is facing the whiteboard.</p>

<p>There is no problem with the video portion, lighting etc. </p>

<p><strong>Tried and didn't work</strong></p>

<ul>
<li><p>She isn't comfortable with head phones, so I tried using Bluetooth earphones and using the Bluetooth audio instead of phone mic but it didn't work reliably. </p></li>
<li><p>Android apps that claim to reduce noise. Results aren't good. </p></li>
</ul>

<p>These questions, emphasized that I should be using a good mic (since post recording processing is not possible) </p>

<ul>
<li><p><a href="https://video.stackexchange.com/q/11953/29714">Microphone suggestions or software to avoid background noise in audio</a></p></li>
<li><p><a href="https://video.stackexchange.com/q/20350/29714">How to reduce background noise in the video</a></p></li>
</ul>

<p><strong>Questions</strong></p>

<ul>
<li><p>What kind of mic and the typical characteristics of the mic I should be looking for? </p></li>
<li><p>Is there any other alternative solution apart from mic? For instance, a paid Android app that can do this for sure? Or something else? </p></li>
</ul>

<p>We are on a budget and since the videos aren't meant to be high quality anyway, <strong>low cost solutions</strong> are preferred. It would be nice if someone could link a product from Amazon (India) as an example. </p>

<p>PS: Lengthy question, yes, to make sure the situation is clear and hoping for a workable solution</p>
 29714: <p>Answering my question with a no extra cost solution using the Noise cancellation headset I had.</p>
<p>Using any Bluetooth headset (even supporting BT 5.0) like <a href="https://www.amazon.in/dp/B07N1V83HP/ref=cm_sw_r_other_apa_i_.p8WEb9DJ6EVN" rel="nofollow noreferrer">Crossbeats</a>
and recording with stock camera app or with <a href="https://play.google.com/store/apps/details?id=net.sourceforge.opencamera" rel="nofollow noreferrer">Open Camera</a> with audio source set to external doesn't work.</p>
<hr />
<h1>Solution</h1>
<ul>
<li><p>I had a <a href="https://rads.stackoverflow.com/amzn/click/com/B005LISQ0W" rel="nofollow noreferrer" rel="nofollow noreferrer">Bose BT2 Bluetooth headset</a>, which I haven't used in the last 7 years and surprisingly charged up and gives me about an hour of usage time which is more than enough. I wanted to use this to improve the quality of recording since it has excellent noise cancellation. You may as well pick up any recent BT headsets of your choice and of recent vintage. Profiles supported by Bose headset are
<code>HSP, HFP, A2DP - SNK, AVRCP</code></p>
</li>
<li><p>Download <a href="https://play.google.com/store/apps/details?id=com.codococo.monomono" rel="nofollow noreferrer">Bluetooth Mono Router</a>. Blogs and YouTube videos recommend <a href="https://play.google.com/store/apps/details?id=com.bedoig.BTmono" rel="nofollow noreferrer">BTmono</a> but it hasn't been updated for Android 10 and won't work. Both these apps have the same functionality - they let you play BT audio to those old headsets which only support voice calls and not media. <em>I am not clear as to how this let's you overcome the limitations of recording but it works</em> (someone here may have an explanation) . You can use either stock camera app or Open Camera (audio as external in settings)</p>
</li>
<li><p>In case you can't record, activate developer options and from Bluetooth settings try <code>AVRCP 1.3 and SBC codec</code> combination. These seem promising. In my case I used default</p>
</li>
</ul>
<hr />
<p>Permit me  a little rant about One Plus tech support with interactions over several mails. YMMV. Documenting it just in case it helps others.</p>
<ul>
<li><p>They do not respond when you ask them how to record using Bluetooth.</p>
</li>
<li><p>Using wired Lavalier solutions need an extra adapter in some cases and even then no guarantees. Reason : <strong>Non standard implementation</strong> of USB C to audio adapter (Shades of <a href="https://arstechnica.com/gadgets/2015/11/oneplus-admits-that-its-selling-dodgy-usb-type-c-cables-and-adapters/" rel="nofollow noreferrer">wrong resistance used in early models</a>)
. They claim on mail that TRRS is <em>not supported</em> since it is a <em>third party</em> affair and when confronted with standards do not reply</p>
</li>
</ul>
 26178: <p>Forget an app. The truth is that a mic is, not only the best option but also an honest option. It will help the audience to focus on the content instead of making it a pain to hear.</p>

<p>I would go for a cable lavalier mic, there are some in amazon, and they are the cheapest alternative.</p>

<p><a href="https://www.amazon.com/s?k=cellphone+microphone" rel="nofollow noreferrer">https://www.amazon.com/s?k=cellphone+microphone</a></p>

<p>The other option is a shotgun mic, but they are a bit more expensive, and normally are for outdoor usage and for interviews for example. For one person a lavalier is the best alternative.</p>

<p>You could also try a "hands-free" earphone with a mic. Probably your cellphone came with one already.</p>

<hr>

<p><strong>Why a lavalier?</strong></p>

<p>The way a lavalier mic reduces the ambient noise is... It does not.</p>

<p>But the ratio of the proximity to your mouth, let's say 10cm or 4in to any other source of a sound, a fan, that can be 2mts away is 20 times the distance. And depending on the echo of the room, this difference could make the sound less prominent by one law that is the inverse square law that makes this difference exponential.</p>

<p>But if you have your camera at let's say 2m away from you, using the internal mic, and the fan is above you, the ratio of distances is probably only 1.5 times. So when you record your voice, you need to pump the volume, therefore you also pump the volume for the fan.</p>

<hr>

<p>Hands-free is not the same as Bluetooth. There are cable options.</p>

<p>Regarding a blue tooth or not, I can not recommend anything. Bluetooth has the risk of having some delay, or not. If that is not important, because you are not showing the face it is ok. But this depends on the model or brand. I suppose if you buy one Bluetooth hands-free for some brand it would recognize that device.</p>

<p>Cable or Bluetooth is just a way to connect a device. That is up to you and you need to make some homework to see if the device fits your phone.</p>

<p>But normally a lavalier mic is expected to have better sound quality than mic on a hands-free device. Of course, depends on the brand.</p>

<p>Some cable lavalier mics need batteries, make sure to buy some extra. Also, check the length of the cable.</p>

<p>You could add some cable extension, but that is not recommended because you could add electronic noise into the signal, but you could try. The not so cheap option is a lavalier with a UHF transmitter.</p>
