Abstract: Among other things, one or more non-transitory machine-readable media storing instructions are described. The stored instructions are executable by one or more processing devices to perform operations comprising analyzing an effect of noise in a spatial unit on sound in the spatial unit, at least part of the sound being produced by audio signals; selecting an adjustment curve among a group of adjustment curves based on one or more characteristics of the noise; and determining an amount of adjustment to be made to the audio signals based on the analyzed effect and the selected adjustment curve.

Abstract: Among other things, one or more non-transitory machine-readable media storing instructions are described. The stored instructions are executable by one or more processing devices to perform operations comprising analyzing an effect of noise in a spatial unit on sound in the spatial unit, at least part of the sound being produced by audio signals; selecting an adjustment curve among a group of adjustment curves based on one or more characteristics of the noise; and determining an amount of adjustment to be made to the audio signals based on the analyzed effect and the selected adjustment curve.

Abstract: A modulated power supply comprises first and second coding units. The second coding unit is responsive to a feed-forward error signal representing the error between the coded output of the first coding unit and an input modulating signal. The second coding unit codes for the more limited range of the error signal, thereby improving resolution. The first coding unit can comprise M coding units arranged in parallel with one another. The M coding units are operated in a manner which increases the apparent number of quantisation levels. This is achieved by feeding a modified version of the input modulating signal to each of the M coding units or by offsetting by quantisation grids of the M coding units. The improvements are particularly useful for improving performance where the input modulating signal has a wide bandwidth.

Abstract: A noise suppressor system uses a set of parallel bandpass filters to transform an input signal into a plurality of spectral adjacent band signals. Each band signal may then be substantially attenuated (squelched) by an attenuation-control circuit when it drops below a predetermined noise threshold. All band signals are then summed to reform essentially the original but noise-suppressed signal. Features of the invention include essentially linear control-attenuation circuitry, and ganged input-output manual level controls for dynamic range matching at constant overall gain.

Abstract: A single adjustable control is commonly connected with each of a plurality of feedback channels, which are selectively coupled in an amplifier circuit to provide the latter with different basic gains, to adjust the respective basic gains of the amplifier circuit by corresponding fractional or proportional amounts of respective ranges of permissible gain chain for each channel, thereby simultaneously to correct or to calibrate each channel for different amounts of drift of the like.

Abstract: An amplifying system comprises an amplifier having a certain constant gain, a first variable attenuator through which an input signal for this system is inputted to the amplifier, and a second variable attenuator through which the output signal of the amplifier is delivered. The over-all gain of the system is variable from the minimum gain to the maximum gain by gang-operating the two variable attenuators. The two variable attenuators are of such a construction that the attenuation factor of the first attenuator is substantially variable in the operation range near the middle of the variable gain whereas that of the second attenuator is substantially variable in the operation ranges near the minimum and maximum of the variable gain. When the input signal level is low, the second attenuator functions in the near-maximum range, and when high, the first attenuator functions in the middle range, thus delivering an output signal at the rated level.