Different embodiments of methods and apparatus to produce audio output signals are disclosed. In one embodiment, an ultrasonic speaker outputting ultrasonic signals can be transformed into first audio output signals, which are directional. A non-ultrasonic speaker can output second audio output signals. The embodiment can be configured to output the first audio output signals or the second audio output signals in a vehicle. Another embodiment can be configured to output the first and the second audio output signals together. Yet another embodiment can be configured to be personalized to hearing characteristics of a user, or to depend on sound level of an environment of the user. One embodiment can include a directional speaker attached to a vehicle, with its output steerable towards a user in the vehicle.

Different embodiments of methods and apparatus to produce audio output signals are disclosed. In one embodiment, an ultrasonic speaker outputting ultrasonic signals can be transformed into first audio output signals, which are directional. A non-ultrasonic speaker can output second audio output signals. The embodiment can be configured to output the first audio output signals or the second audio output signals in a vehicle. Another embodiment can be configured to output the first and the second audio output signals together. Yet another embodiment can be configured to be personalized to hearing characteristics of a user, or to depend on sound level of an environment of the user. One embodiment can include a directional speaker attached to a vehicle, with its output steerable towards a user in the vehicle.

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for analyzing ultrasonic signals to recognize mouthed articulations. One of the methods includes generating an ultrasonic carrier signal and coupling the ultrasonic carrier signal to a person's vocal tract. The method includes detecting a modulated ultrasonic signal, the modulated ultrasonic signal corresponding to the ultrasonic carrier signal modulated by the person's vocal tract to include information about articulations mouthed by the person; analyzing, using a data processing apparatus, the modulated ultrasonic signal to recognize the articulations mouthed by the person from the information in the modulated ultrasonic signal; and generating, using the data processing apparatus, an output in response to the recognized articulations.

Techniques described herein generally relate to generating an audio signal with a speaker. In some examples, a speaker device is described that includes a membrane, an acoustic cavity and an acoustic channel. The membrane can be configured to oscillate along a first directional path and to generate an acoustic signal. The acoustic signal traverses the acoustic channel and generates an audio signal.

The pilot communication system employs an acoustic transducer disposed on the flight deck and positioned to emit sound waves in the direction of the at least one pilot seating location. A modulator circuit is coupled to receive an audio signal from the avionics communication system and is also coupled to drive the acoustic transducer. The modulator circuit supplies to the acoustic transducer an electrical signal having an ultrasonic carrier frequency modulated by the audio signal, thereby causing the acoustic transducer to deliver a beam of ultrasonic acoustic energy, through the acoustic space, in the direction of the at least one pilot seating location, which beam of ultrasonic acoustic energy is demodulated naturally by traversal through air molecules between the transducer and the pilot seating location, thus rendering the audio signal audible by human hearing at the at least one pilot seating location.

Techniques described herein generally relate to generating an audio signal with a speaker. In some examples, a speaker device is described that includes a membrane and a shutter and driver device is configured to receive an audio signal, modulate it and generate electric signals to operate the speaker and generate an acoustic audio signal.

An air-pulse generating device includes a film structure. The film structure is driven by a modulation-driving signal, so as to form an amplitude-modulated ultrasonic air pressure variation with an ultrasonic carrier frequency. The film structure is driven by a first demodulation-driving signal and a second demodulation-driving signal, so as to form an opening at a rate synchronous with the ultrasonic carrier frequency. The air-pulse generating device produces a plurality of air pulses according to the amplitude-modulated ultrasonic air pressure variation.

An air-pulse generating device includes a film structure including a flap pair. The film structure is actuated to perform a common mode movement, so as to form an amplitude-modulated ultrasonic air pressure variation with an ultrasonic carrier frequency. The film structure is actuated to perform a differential mode movement, so as to form an opening at a rate synchronous with the ultrasonic carrier frequency. The air-pulse generating device produces a plurality of air pulses according to the amplitude-modulated ultrasonic air pressure variation.

Ultrasonic transducers that are capable of generating increased levels of ultrasound, as well as receiving ultrasonic waves with increased sensitivity. The ultrasonic transducers include a back cover, a protective front cover, a backplate, and a vibrator film layer disposed between the backplate and the protective front cover. The backplate includes a plurality of grooves formed on a surface thereof facing the vibrator film layer. Each groove includes upper edges having cross-sectional contours that gradually tend toward the deepest part of the groove to allow a larger area of the backplate to be closer to the vibrator film layer, thereby increasing the resulting electric field, and, consequently, increasing the output power and sensitivity of the ultrasonic transducer.

A method of improving sound quality of an ultrasonic speaker device includes: a first operation of removing a low frequency component of an input audio signal by using a high pass filter; a second operation of correcting a response characteristic of a signal obtained by removing the low frequency component, for each frequency band by using an equalizer; a third operation of adjusting a sound pressure level of a signal obtained by correcting the response characteristic for each frequency band; and a fourth operation of controlling a signal magnitude not to increase above a particular level by using a limiter, in order to prevent a signal clipping that may occur in the second operation and the third operation. An audio signal of improved sound quality may be transmitted to a listener by applying a sound quality improving method suitable for the characteristics of a super-directional ultrasonic speaker.