Sound healing is a complementary relaxation practice, not medical treatment, and nothing on Sacred Frequency is a diagnosis or a substitute for professional care.
The genuine safety considerations are volume and duration. Keep the volume low enough to hold a conversation over, and sessions to twenty minutes or so. Anyone with epilepsy or another seizure disorder should avoid rhythmic audio stimulation without medical advice, as should anyone with a pacemaker or an active heart condition. Stop if you get a headache, nausea or ringing in the ears.