Distance estimation using sound signals

Abstract

An apparatus comprises a test signal generator (401) which generates an ultrasonic test signal by modulating an audio band test signal on an ultrasonic signal. The ultrasonic test signal is radiated from a parametric loudspeaker (403) and is demodulated by non-linearities in the air. A reflected audio signal may arise from reflections of an object, such as a wall. An audio band sensor (405) generates an audio band captured signal which comprises the demodulated reflected audio band signal. A distance circuit (407) then generates a distance estimate for the distance from the parametric loudspeaker (403) to the object in response to a comparison of the audio band captured signal and the audio band test signal. Specifically two signals may be correlated to determine a delay corresponding to the full path length. Based on the distance estimates an audio environment may be estimated and a sound system may be adapted accordingly.

Description

technical field [0001] The present invention relates to the estimation of distance to objects, and in particular but not exclusively to the characterization of an audio environment based on the estimation of distance. Background technique [0002] Automatic determination of distance is important for many applications. For example, the audio environment greatly affects the performance of loudspeaker systems and, for example, the acoustics of a room significantly affects the spatial experience that can be provided with a spatial sound reproduction system. In order to provide the best possible spatial rendering, it is therefore important that the sound reproduction system is properly calibrated to the specific audio environment. Since it is not possible to account for every possible permutation of room size, sound system position and listener position etc. in advance, it is only possible to provide a limited number of preset options in practice. Proper calibration of the soun...

AI Technical Summary

Problems solved by technology

[0005] Another problem faced by the use of conventional loudspeaker arrays is that the large aperture required for high directivity also results in a large audio beam spot size which reduces the resolution of the measurement system

In fact, in many cases even small deviations from the vertical angle lead to measurement signals corresponding to paths with multiple reflections (e.g. more walls), leading to erroneous results and thus e.g. Incorrect calibration of the regenerative system

Such ultrasonic ranging systems are therefore often impractical for many fixed calibration systems where the ranging device cannot be practically located and pointed directly at the object to which the distance is being measured

In particular, these systems tend to require manual operation and are unsuitable for use in many automated systems where the exact position and orientation from the ranging device to the object is not known

Images