Thanks to Steve Reynolds for measuring his SHO's interior frequency response. The series show the Front & Rear, Front only, and Rear only response.

The measurements were made using a Radio Shack db meter held at ear level in the passenger's seat. A Hewlett Packard function generator was connected to the CD input pins on the Ford Premium Sound Head unit. All controls were centered in their mid-positions. The SHO has a cloth interior. All windows were closed. A reference of 90db at 1000hz was used for the three tests.

The low frequency response is easily repeatable. The high frequencies can easily have 10 db variations with minor placement changes of the db meter or other movements within the SHO.

One general comment is the treble control provides 10db boost at 20,000hz.

Thanks to Andrew Blackburn for producing the graph from Steve's data.