For the DFPlayer mini, and for my device to output sounds, I need a speaker. However, speakers come in different sizes and with different quality of audio and volume.
So I have taken/bought 6 speakers and tested all of them to check for the best one.
And I attached wires to all of them:
One thing that I noticed is that certain speakers would sound better when pushed towards the desk.
This is called a "baffle" and when done properly and the speaker is sealed in an enclosure, then it becomes an "infinite baffle". The infinite baffle is a closed and sealed box that aims to smother the rear sound waves from the loudspeaker. In this way there is no cancellation caused by the rear sound wave from the loudspeaker.
I received some details in regards to it on the Arduino Forums after asking about it and about any small speakers there may exist. The link to my post is available here:https://forum.arduino.cc/t/smallest-speaker-wearable-project/979258/7
And then I proceeded to test all of them, video recording from circa 15cm away with my phone while keeping the distance constant between all speakers, max volume (30) from DFPlayer Mini.
After that, I have redone the test, this time with a "Sound Meter" app on my phone, with the phone microphone 3 centimeters away from the speaker.
1) Piezo Speaker - Comment: Not useful for my purpose.
No DB reading, volume too low.
2) Simple and small 1watt 8 ohm impedance speaker (available on Ebay, Amazon etc. generic brand). Comment: decent, but there are better solutions, volume and audio quality mediocre.
3) RS PRO Speaker 1.5watt 8ohm impedance. Comments: very powerful for the size, however the audio quality is not that great.
4) RS PRO Speaker 2 watts 8ohm impedance. Comments: very loud, however, decent audio quality. Comments: can get very loud, but the speaker is quite big and the audio quality is decent.
5) Iphone XR Loud speaker. Can get loud, does not require to be sealed to form an infinite baffle, the audio quality is almost the best out of all speakers.
6) Iphone 12 Pro Max Loud speaker. Can get loud (just a fraction lower in volume than the XR), does not require to be sealed to form an infinite baffle, the audio quality is the best out of all speakers, even the XR speaker.
Ultimately, depending on the space available in the shell of my device, I will go with the Iphone 12 Pro Max or Iphone XR loud speaker, both have a similar volume, but the form factor is quite different, so I will use the best match.