A portable loudspeaker includes an electro-acoustic driver which creates sound waves when operated and a housing having a front side to which the driver is secured. The loudspeaker also includes a battery supported by the housing for providing electrical power to the driver and a cover having an upper portion and a lower portion, and secured to the housing which can be moved between (i) a closed position in which the upper and lower portions overlie the driver, and (ii) an open position in which the upper and lower portions do not overlie the driver and are substantially disposed beneath a supporting base of the housing. A controller controls operation of the loudspeaker. When the cover is moved to the closed position, the controller mutes the driver if the driver was outputting acoustic waves when the cover was moved to the closed position.

To control loudness during a junction between different types of broadcast content, such as a junction between programme and commercial or promotional content, representative loudness values for content respectively before (P) and after (C) the junction are received from a playout automation system. A time-varying gain control is applied before and after the junction in order to smooth loudness around the junction. The audio gain is smoothly increased prior to the junction to a gain (P+C)/2P times higher than the original gain value. Then, the gain is reduced shortly before the junction to a value (P+C)/2C times lower than the original gain value. After the junction, the gain is returned smoothly to the original value.

Systems and methods for handling silence in audio streams are disclosed. In one aspect, a transmitter detects a halt in an audio stream. After detection of the halt in the audio stream, the transmitter embeds a silence signal into the audio stream and transmits the silence signal to associated receivers. The associated receivers may respond to the embedded silence signal by “playing” silence or by using the silence signal to activate a silence protocol. In either event, the associated receivers do not receive the original audio halt and do not produce an unwanted audio artifact.

A radio module may be configured to receive a starter motor relay signal from a first control module indicative of a motor start. The module may in turn mute a sound device associated with the radio module and upon receiving a delayed accessory signal from a second control module indicative of a delayed accessory trigger, un-mute the sound device in response to receiving the delayed accessory signal.

This application describes methods and apparatus for selectively clamping a signal path (106) for an analogue audio signal to a clamp voltage, e.g. ground. Voltage clamping circuitry (200) is disclosed having a first switching device (201) in series with a second switching device (202) between a node of the signal path and the clamp voltage. The clamping circuitry is configured to be operable in: a first state where the first and second switching devices are both on to electrically connect the signal path to the clamp voltage; and also a second state to electrically disconnect the signal path from the clamp voltage. In the second state one of the first and second switching devices is configured to block conduction when the voltage at said node of the signal path is positive and the other switching device is configured to block conduction when the voltage at said node of the signal path is negative.

A method of operating a headphone configured to be removed from and placed in close proximity to a user's ear can include generating an input signal by an input signal generating device. The method can also include determining whether an insertion event has occurred based on the generated input signal and causing the headphone to operate in 5 a low power mode responsive to an absence of an insertion event determination after a first period of time. The method can also include causing the headphone to operate in an ultra-low power mode responsive to the absence of an insertion event determination after a second period of time that occurs after the first period of time, the ultra-low power mode having a lower power consumption than the low power mode.

The present disclosure relates to an apparatus for preventing noise in an electronic device. An apparatus for preventing noise in an electronic device includes a microphone unit including a microphone, the microphone unit connected to a first power terminal and a second power terminal, and a switch unit including at least one switch and at least one resistance, the switch unit connected to the first power terminal and the microphone in series.

In some embodiments, an audio amplifier can be controlled by a method that includes generating an enable signal based on a masking sound in an audio signal, and controlling a mode transition of the audio amplifier between a current source mode and a voltage source mode based on the enable signal. The mode transition of the audio amplifier can result in an artifact sound, the generating of the enable signal and the controlling of the mode transition can be achieved such that the artifact sound is substantially masked by the masking sound.

A voltage clamping circuit is provided. In an embodiment, the voltage clamping circuit includes a plurality of gain shifting circuits and a signal processing circuit. The plurality of gain shifting circuits receive an input voltage and voltage levels to generate a plurality of shifted voltages. The signal processing circuit generates a difference value of the plurality of shifted voltages to generate an output voltage according to the difference value, such that the voltage clamping circuit achieves an implementation of a passing band or a rejection of the input voltage.

Circuits, devices and methods related to mode-switching of amplifiers. In some embodiments, an audio controller can include a mode state engine configured to receive an enable signal and generate a control signal for controlling a mode transition of an amplifier between a current source mode and a voltage source mode, with the mode transition of the amplifier resulting in an artifact sound. The audio controller can further include an enable component configured to provide the enable signal to the mode state engine based on a masking sound in an audio signal, such that the artifact sound is substantially masked by the masking sound during the mode transition of the amplifier.