An example method includes receiving data indicating a configuration of one or more playback devices. The one or more playback devices may include one or more transducers. The method further includes, based on the received data, associating each of one or more audio streams respectively with at least one transducer of the one or more transducers. The method further includes generating the one or more audio streams and sending at least one of the generated one or more audio streams to each of the one or more playback devices. An example non-transitory computer readable medium and an example computing device related to the example method are also disclosed herein.

Apparatus comprises one or more first microphones for providing audio signals from captured acoustic signals; one or more conductive terminals for connection to one or more conductive terminals of an external cover device for receiving audio signals provided by one or more second microphones included in the external cover device; and one or more processors coupled to the one or more first microphones and to the one or more conductive terminals and configured to perform audio processing on the audio signals from the one or more first microphones and/or from the one or more second microphones based on a control input. Cover apparatus comprises one or more microphones and one or more conductive terminals for providing audio signals provided by said one or more microphones to the electronic apparatus.

An optimised method for driving a loudspeaker is used for protecting the loudspeaker from damage due to excessive excursion or from overheating. The playback power of an incoming audio data stream is compared with a feedback power derived from the loudspeaker actuator and the comparison is used to adjust the frequency response of the loudspeaker, across individual sub bands.

Equalizer circuitry includes a differential target voltage input, an equalizer output, a first operational amplifier, and a second operational amplifier. The differential target voltage input includes a target voltage input node and an inverted target voltage input node. The first operational amplifier and the second operational amplifier are coupled in series between the differential target voltage input and the equalizer output. The first operational amplifier is configured to receive a target voltage signal and provide an intermediate signal based on the target voltage input signal. The second operational amplifier is configured to receive the intermediate signal and an inverted target voltage signal and provide an output signal to the equalizer output. The first operational amplifier and the second operational amplifier are interconnected with one or more passive components such that a transfer function between the differential target voltage input and the equalizer output is a second-order complex-zero function.

An example method of operation may include initiating an automated tuning procedure, detecting via one or more microphones a sound measurement associated with an output of one or more speakers at two or more locations, determining a number of speech transmission index (STI) values equal to a number of microphones, and averaging the speech transmission index values to identify a single speech transmission index value.

Example techniques involve calibration of one or more playback devices. An example implementation involves a playback device playing back audio content using a first calibration via the one or more audio transducers and the one or more amplifiers. The first calibration is based on a response of a listening environment to audio content playback by the playback device. The playback device records, via one or more microphones, at least a portion of the played back audio content. Based on the recorded audio content, the playback device detects a change in the response of the listening environment to audio content playback by the playback device. Responsive to detecting the change in the response, the playback device causes output of a prompt to initiate a calibration procedure for the playback device. The calibration procedure involves a mobile device recording playback by the playback device.

A speech signal leveling system and method include generating an output signal by applying a frequency-dependent or frequency-independent controllable gain to an input signal, the gain being dependent on a gain control signal, and generating at least one speech detection signal indicative of voice components contained in the input signal. The system and method further include generating the gain control signal based on the input signal and the at least one speech detection signal, controlling the controllable-gain block to amplify or attenuate the input signal to have a predetermined mean or maximum or absolute peak signal level as long as voice components are detected in the input signal.

A limiter system for an active speaker may include at least one lowpass filter configured to receive an input signal and output a signal lower than a crossover frequency, at least one highpass filter, configured to receive an input signal and output a signal higher than the crossover frequency, a first allpass filter configured to adjust the phase of the signal lower than the crossover frequency, a second allpass filter configured to adjust the phase of the signal higher than the crossover frequency, a first limiter, configured to receive and limit the signal from the first allpass filter, a second limiter, configured to receive and limit the signal from the second allpass filter, and a mixer, configured to mix the signal lower from the first limiter and the signal from the second limiter.

An aspect of the present disclosure is directed to systems, methods, and software products that enhance the sound and perception of bass energy in loudspeaker systems which have limited response in the low frequency spectrum. The systems, methods, and software products provide for (i) receiving one or more bass sub-bands of audio channel content, wherein each bass sub-band is separated from an audio program content spectrum including high-band energy; (ii) applying boost to each bass sub-band to compensate for rolloff of the speaker system; (iii) applying a limiter to prevent speaker saturation at low frequencies and/or high volume levels; and (iv) combining each bass sub-band along with the high band energy for sending as a recombined audio signal to the speaker system for rendition as physical sound.

A speech intelligibility enhancing system for difficult acoustical conditions is disclosed, the speech intelligibility enhancing system comprising at least one ear plug (201) for insertion in an ear canal (218) of a person, the at least one ear plug being arranged with an ear canal facing portion (401) and an environment facing portion (402), and the at least one ear plug comprising an acoustically attenuating path (214; 214, 213) comprising a vent (214) coupling said environment facing portion (402) with said ear canal facing portion (401); and an electroacoustic path (202, 204, 209; 202, 203, 204, 208, 209, 210, 211, 212) comprising a microphone (202) at said environment facing portion (402), a variable gain (204) and a loudspeaker (209) at said ear canal facing portion (401); wherein said acoustically attenuating path (214; 214, 213) is arranged with a transfer function from said environment facing portion (402) to said ear canal facing portion (401) having a low pass characteristic having a low pass cut¬off frequency and said low pass characteristic attenuating sound by a nominal attenuation (Go) for frequencies below said cut-off frequency.