Reproduction steps:
1. Open the attached project 'TapTest'.
2. Play the 'Main' scene.
3. Click on the buttons.
- Hear the sounds.
4. Build this scene to a device.
5. Click on the buttons.
- Compare the sounds with the Editor sounds.
6. Download the 'information' archive from the attached files.
7. Compare 3 screenshots in the information folder (My results attached to the bottom of the case):
- 1_元の波形 - original audio.
- 2_48kHz, 3_44kHz - audio on a device.
- Notice, that there is new data under 2kHz and cut sound over 12kHz.
- Can be tested using audio analyzers (http://spek.cc/).
8. Open and listen 'SE_test' file, sounds are recorded in this order:
- Original audio
- 48kHz Vorbis iOS
- 48kHz Vorbis Android
- 44.1kHz Vorbis iOS、
- 44.1kHz Vorbis Android
- 44.1kHz PCM iOS
- 44.1kHz PCM Android

Reproduced with:
5.5.5f1, 2017.3.0b2
iPhone 6+ iOS 8.0
iPhone 5s iOS 9.3.3
iPadMini 4 iOS 11.0
Samsung Galaxy S7 (SM G930F) Android OS 7.0

Not reproducible with:
macOS Editor
macOS Standalone
Google Pixel Android OS 8.0.0

Resolution:
- Some devices default smaller sample rate to get a faster sound response time.
- To force a higher sample rate, use this snippet:

...
AudioConfiguration config = AudioSettings.GetConfiguration();
config.sampleRate = 48000; //Change 48000 to a desireable sample rate
AudioSettings.Reset(config);
...