Using a soft-bristled toothbrush, brush the speaker ports.  This gentle motion should clean grime and gunk off the speakers. You could dip the very tips of the toothbrush bristles in rubbing alcohol for added effect.  Don’t dip the whole brush in. Painter’s tape is a blue tape used when painting walls.  It has a pressure-sensitive adhesive, which makes it perfect for cleaning iPhone speakers.  Tear a short piece off and roll it into a cylinder with the sticky side facing out.  The cylinder should have a diameter about the width of your index finger. Slip the tape over your index finger, then press it onto your iPhone speaker. The tape should pick up all the grime and bits that have accumulated in the speakers. Check the surface of the tape after each application.  If you see lint and grime stuck to it, remove and discard the used tape, roll another small cylinder, and repeat. Use compressed air to blow lint and dust out of your speakers.  Compressed air is canned oxygen, and is often used to clean computers and electronics.  To get started, lay your phone flat with the screen down.  Read the directions on the can before using it.  Always use canned air as directed. Aim the canned air nozzle at the speaker from whatever distance the can’s directions suggest. Squeeze the can’s handle briefly, then release.

TL;DR in Indonesian:
Gosok pengeras suara. Gunakan selotip seniman. Tiup kotoran dari pengeras suara.