The Stream 3 is a Dual Mode Player. This means it accepts either our Surge, SX10 or Bone Conduction  Series headphones. DYNAMIC SPEAKERS We use our patented waterproofing technology that sometimes requires the speakers to be equalized due to pressure. Think of the speakers as an empty plastic water bottle - and if you take that in an airplane it will deform due to ambient pressure which is different from the pressure inside the bottle. We need to get the bottle to release and pop it back to normal form. If there is a faint or muffled sound this can be resolved via the  troubleshooting steps below. If there is buzzing crackling or is completely silent this cannot be fixed. In this case, please contact us directly: support@h2oaudio.com.   If you are experiencing sound quality issues - there are a few possible scenarios: There is water trapped between the speaker and the earplug. Solution: tap the speakers and try to get the drop of water out. Also gently blowing into the speaker might help. Once the water dries up - it should sound normal. To avoid this during swimming, try different size earplugs and find one that keeps the best seal/fit. The speaker is not completely equalized. Solution: Play loud/full volume music through the speakers and let the music run for a while. This will slowly help equalize the speakers. To expedite, you can gently suck and blow air into the speaker which will reset the membrane. If you remove the blue ear tips and tap the speaker on a firm surface you can release the membrane. Soak the affected speaker in very warm water to break down any residue or build up - repeat steps 1-4. Please test the headphones on a different device to determine if the issue is the source device or the headphones. BONE CONDUCTION SPEAKERS The  H2O Audio Surge Bone Conduction headphones are only compatible with StreamDM and Stream Pro. If you are experiencing sound issues make sure your player is compatible. The H2O Audio Surge Bone Conduction headphones are NOT compatible with Stream 2. For lack of sound in one channel or distortion check the input jack and make sure the jack is pushed all the way into the player. If either side of your Interval bone conduction speakers is not producing sound please reach out directly via email: support@h2oaudio.com.