An apparatus for determining a room dimension estimate including a receiver providing an acoustic room response, a peak detector detects a set of peaks in the acoustic room response in a frequency interval having an upper frequency of no more than 400 Hz, a store includes a set of peak profiles with associated room dimension data, and an estimator determines the room dimension estimate from the associated room dimension data and a comparison of the set of peaks to the peak profiles. The estimator may perform the steps of first finding a matching peak profile for the set of peaks from the set of peak profiles; extracting first room dimension data associated with the matching peak profile(s) from the store; and determining the room dimension estimate in response to the first room dimension data. The peak profiles may represent calculated Eigenfrequencies.