During his earlier years Hansen's singing style was reminiscent of many thrash metal vocalists.
Rather than using a smooth and clear style (like his successor Kiske) Hansen sang with a raspy sound, interluded by high-pitched screams for dramatic effect.
Kiske was brought in as a singer originally because Hansen had trouble singing and playing the guitar simultaneously though later in his career he seems to have overcome these problems.

Beginning from 1995 onward, Hansen has provided the vocals for his current band Gamma Ray.
Around that time, Hansen's vocal style became more melodic and slightly clearer, more in the traditional power metal sense, while still retaining the slight nasal tone and rasp of his early years.
During his earlier years Hansen's singing style was reminiscent of many thrash metal vocalists. Rather than using a smooth and clear style (like his successor Kiske) Hansen sang with a raspy sound, interluded by high-pitched screams for dramatic effect. Kiske was brought in as a singer originally because Hansen had trouble singing and playing the guitar simultaneously though later in his career he seems to have overcome these problems.
Beginning from 1995 onward, Hansen has provided the vocals for his current band Gamma Ray. Around that time, Hansen's vocal style became more melodic and slightly clearer, more in the traditional power metal sense, while still retaining the slight nasal tone and rasp of his early years.
Kai Hansen