A method of operating a personal audio device configured to be removed from and inserted into 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 personal audio device to operate in 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 personal audio device 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.

Systems and methods for low power lattice wave filters include an input operable to receive a digital input signal having a first sample rate, a first processing branch including a first delay element operable to receive the digital input signal and output a delayed digital input signal, a second processing branch including a first adder operable to receive the digital input signal and subtract a delayed feedback signal to produce a difference signal, a second adder operable to combine the delayed digital input signal and the difference signal to produce an output signal, and wherein the second processing branch further includes a feedback path including a second delay element operable to receive the output signal and output the delayed feedback signal. In a multistage topology, a register is disposed between each stage and clocked to reduce ripple power.

A method for reducing the power of an acoustic primary noise signal (d.sub.m(n)) at one or more control positions in a vehicle passenger compartment using an adaptive filter. The method comprising to compare a mean correlation coefficient (.sub.m(n)) between an electrical error signal (e.sub.m(n) and a modelled secondary anti-noise signal .sub.m(n) with at least one predefined threshold (, ).

An anti-noise signal generator and a method of generating an anti-noise signal are presented. The anti-noise generator includes a first microphone input to receive a first sigma-delta modulated signal at a microphone sampling frequency. The first microphone input is coupled to a combiner via a first path and a second path. The combiner is adapted to combine a first filtered signal from the first path and a second filtered signal from the second path to generate the anti-noise signal. The first path includes a first digital filter adapted to operate at a filter frequency equal or greater than the microphone sampling frequency. The second path includes a second digital filter. The first digital filter may be a sigma-delta based filter that includes a sigma-delta modulator.

A digital circuit arrangement for an ambient noise-reduction system affording a higher degree of noise reduction than has hitherto been possible. The arrangement converts the analog signals into N-bit digital signals at sample rate f.sub.0, and then subjects the converted signals to digital filtering. The value of N in some embodiments is 1 but, in any event, is no greater than 8, and f.sub.0 may be 64 times the Nyquist sampling rate but, in any event, is substantially greater than the Nyquist sampling rate. This permits digital processing to be used without incurring group delay problems that rule out the use of conventional digital processing in this context. Furthermore, adjustment of the group delay can readily be achieved, in units of a fraction of a micro-second, providing the ability to fine tune the group delay for feed forward applications.

An active noise cancellation (ANC) system including a selectable decimation rate decimator that receives an oversampled digital input and has an input that selects the decimation rate, a filter that receives an output of the decimator, and a selectable interpolation rate interpolator that receives an output of the filter and has an input that selects the interpolation rate. The selectable decimation rate decimator and the selectable interpolation rate interpolator operate to provide a selectable sample rate for the filter based on the selected decimation and interpolation rates. The filter may be an anti-noise filter, feedback filter, and/or a filter that models an acoustic transfer function of the ANC system. Rate selection may be static, or dynamically controlled based on battery or ambient noise level. A ratio of the decimation rate and the interpolation rate is fixed independent of the dynamically controlled decimation and interpolation rates.

An ambient sound processing method provided includes determining a time-frequency spectrum of an ambient sound in preset duration. A matching scenario is determined from at least one preset scenario according to the time-frequency spectrum of the ambient sound in the preset duration, where a time-frequency spectrum of the matching scenario matches the time-frequency spectrum of the ambient sound in the preset duration. Operation information corresponding to the matching scenario is determined as the operation information to be executed, and an operation is performed according to the operation information to be executed and a subsequently received ambient sound, and an operated signal is determined. The operated signal is mixed to obtain a mixed signal, and the mixed signal is transmitted to a headset, where the mixed signal includes at least an audio signal played by user equipment of a user.

A control system and method of selectively enabling an auto-shutoff feature of a control system for an aviation headset includes a power switch. The power switch is toggled and if the control system is in a powered down state, a startup sequence for the control system is initiated. During the startup sequence, a bias voltage detector checks for a bias voltage on a signal line of the headset. If a bias voltage is detected during the startup sequence, the auto-shutoff feature is enabled. The auto-shutoff feature periodically checks for a bias voltage and powers down the control system if no bias voltage is detected for a predetermined time interval. If no bias voltage is detected during startup, the auto-shutoff feature is disabled.

This disclosure relates to a headphone device, a terminal device, an information transmitting method, a program, and a headphone system capable of reducing a process burden of parameter control in a noise canceling process of the headphone device. In the terminal device capable of communicating with the headphone device, a parameter appropriate for the noise canceling process is determined based on analysis of noise from outside and position information and indication information to indicate a processing parameter related to the noise canceling process in the headphone device is generated. This is transmitted to the headphone device side. In the headphone device, a processing parameter of the noise canceling process is set according to the indication information. According to this, a process to determine an optimal parameter of the noise canceling process on the headphone device side is not required.

A sound making device and system for generating white noise is disclosed. The sound making device generally includes a substantially dome-shaped device that includes an outer acoustic shell and an inner acoustic shell mounted atop a base tray. Both the outer acoustic shell and inner acoustic shell have slots (or openings) that overlap to create apertures through which rushing air can pass. The amount of slot overlap is variable. Further, a variable speed fan is arranged inside the outer acoustic shell and inner acoustic shell for forcing airflow out of the apertures. The sound making device also includes a controller and user interface for adjusting the speed of the fan. Further, a sound making system is provided that includes the sound making device in combination with a mobile app.