Audio safety guidelines
If you use your BlackBerry Universal Headset at the maximum sound level over an extended period, hearing impairment might occur.
Audio files: The headset can play audio files. When you listen to audio files using a headset, permanent hearing loss might occur if you use the headset at a high volume. Avoid increasing the volume of your headset to block out noisy surroundings. If you experience ringing in your ears or muffled speech, consult a physician to have your hearing checked.