Abstract: For processing a signal applied to an input of audio signal processing devices, for example a speech signal received via a microphone (2) in a speaker-identification or speech recognition system, the signal must have a specific level. For this purpose the signal is applied via an amplifier (4) with variable gain. Before processing begins, the gain is set to an initial value. During processing of the speech signal, it is checked, at regular time intervals, in which range of a plurality of predetermined amplitude ranges the amplified signal is situated, and whether overloading takes place and the frequency which the amplitude of the signal occurs in each of the amplitude ranges is counted. When the signal ends, the optimum gain setting is determined from the histogram of frequencies.

Abstract: In a device for adjusting a movable electro-acoustic sound transducer, an optical duct is connected to the sound transducer which only allows an object, such as a display table or a data display unit, to be viewed completely in one specific position. This position is unambiguously reproducible and so is the position of the sound transducer or microphone relative to the mouth of the speaker. The optical duct may comprise diaphragms or a tube, possibly with intermediate walls, or a phase amplitude grating.The object may be a display unit and the device further comprises a device for generating variable data on the display. If used for speaker identification, the variable data generator projects consecutive instructions on the display so that, the speech recognition process is controlled automatically. The speaker to be identified is then required to keep his mouth in the correct position relative to the microphone.

Abstract: In practice it is often desirable to represent only a given, selectable dynamic range of a measuring signal, preferably in logarithmic form. This is achieved in accordance with the invention in that from the measured value in the form of a binary number only the positions corresponding to the desired dynamic range are selected for forming the base number, the weight of the most significant bits having the value "1" being converted into a binary number. The mantissa is derived from the following positions, i.e. independent of the selected dynamic range, so that even when the most significant bit is in the last position, a mantissa comprising the full number of positions is formed. The magnitude of the dynamic range is chosen by omitting the correspondingly more significant positions of the base number formed for the maximum range.

Abstract: Method and apparatus for producing a grey-tone image having areas of different average density values which are given by an n-digit binary number, all the bits of the binary number being interrogated in parallel by clock patterns. For the area to be printed an elemental area containing 2.sup.n pulses is selected which is printed in a total cycle of 2.sup.n .sup.- 1 clock pulses of the clock pattern. In this total cycle, at each clock pulse the drive of each pair of dots is determined in a manner such that the most-significant bit of the binary number is always used for driving while the remaining bits are used a number of times which depends upon their positional values. For this purpose, for each position of the binary number the clock pattern has a number of clock pulses which corresponds to the value of this position. The clock pulses for the individual positions are non-uniformly distributed in time, however, no clock pulses for the second and any further positions of the binary number coincide in time.