| 摘要 |
A stract A method and a system for equalizing one or more loudspeaker(s), e.g. a hi-fi system, positioned in a room in order to compensate sound reproduction from the loudspeaker for an influence of the room. The method includes measuring a listening position transfer function (L) from electrical input of the loudspeaker (L1) to a sound pressure at a listening position (LP) in the room. A global transfer function (G) representing a spatial average of sound pressure level in the room generated by the loudspeaker (L1) is determined. This global transfer function (G) can either be determined as an average of two or more transfer functions measured in field points scattered across the room or it can be calculated based on an acoustic power output measured from the loudspeaker (L1) together with data regarding sound absorption properties of the room. An upper gain limit (UGL) as a function of frequency is then determined based on an inverse of the global transfer function (G). An equalizing filter (F) is then determined based on an inverse of the listening position transfer function (L), but with its gain being limited to a maximum gain in accordance with the upper gain limit (UGL). Finally, the loudspeaker (L1) is equalized with the equalizing filter (F), the filter (F) being implemented such as a minimum phase approximation by an FIR or an HR filter. Preferably, a lower gain limit (LGL) as a function of frequency is also determined as an inverse of the global transfer function (G), wherein a gain of the equalizing filter (F) is limited to a minimum gain in accordance with the lower gain limit (LGL). By use of the upper and lower gain limits (UGL, LGL) it is possible to implement a system capable of automatically designing the equalizing filter (F) with only simple tasks to perform for an operator of the system. |
