Günther Theile

Method of transmitting or storing masked sub-band coded audio signals

In the transmission of audio signals, the audio signal is digitally represented by use of quadrature mirror filtering in the form a plurality of spectral sub-band signals. The quantizing of the sample values in the sub-bands, e.g. 24 sub-bands, is controlled to the extent that the quantizing noise levels of the individual sub-band signals are at approximately the same level difference from the masking threshold of the human auditory system resulting from the individual sub-band signals. The differences of the quantizing noise levels of the sub-band signals with respect to the resulting masking threshold are set by the difference between the total information flow required for coding and the total information flow available for coding. The available total information flow is set and may then fluctuate as a function of the signal.

Binaural room scanning—A new tool for acoustic and psychoacoustic research

A new technology called ‘‘ binaural room scanning’’ (BRS) is introduced, allowing real‐time virtual loudspeaker reproduction in any virtual room. It is based on a special convolution algorithm for auralization and on the involvement of spontaneous head movements by means of a head‐tracking system. A complete set of relevant dummy head HRTFs is measured for each loudspeaker and the resulting response in the original room. The data are stored and used for convolution. Thus the BRS system does not apply room synthesis methods (e.g., ray‐tracing), but, in contrast, enables accurate virtual binaural listening in a real (cloned) loudspeaker reproduction room. Since natural head movements are realizable in the simulated sound field, it offers new possibilities in the application of listening tests, not only in the area of room acoustics and loudspeaker reproduction, but also for psychoacoustic research. Examples will be reported.