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 cutoff frequency and said low pass characteristic attenuating sound by a nominal attenuation (Go) for frequencies below said cut-off frequency.

A headphone comprises a plurality of actuatable equalization selectors. Each of the selectors corresponds to an equalization setting that includes a preset distribution of relative amplitudes of sounds in predetermined frequency ranges. In one embodiment, each of the plurality of actuatable equalization selectors is a button-type switch. A knob-type switch or a voice recognition mechanism can also actuate an equalization setting. In a preferred embodiment, an equalizer identification indicator produces a communication perceivable to a headphone wearer and which corresponds to an equalization setting. The communication can be audible or tactile. In some embodiments, the communication is a piece of music or a sound imitation associated with a particular genre of music that corresponds to the equalization setting selected by a headphone wearer. In some embodiments, the communication is an audio clip created or selected by a user and stored in the headphone.

Some embodiments of the invention are directed to enabling a user to easily identify the frequency range(s) at which sound masking occurs, and addressing the masking, if desired. In this respect, the extent to which a first stem is masked by one or more second stems in a frequency range may depend not only on the absolute value of the energy of the second stem(s) in the frequency range, but also on the relative energy of the first stem with respect to the second stem(s) in the frequency range. Accordingly, some embodiments are directed to modeling sound masking as a function of the energy of the stem being masked and of the relative energy of the masked stem with respect to the masking stem(s) in the frequency range, such as by modeling sound masking as loudness loss, a value indicative of the reduction in loudness of a stem of interest caused by the presence of one or more other stems in a frequency range.

Example techniques facilitate calibration of a playback device. An example implementation involves a computing device capturing, via a microphone, data representing multiple iterations of a calibration sound as played by a playback device. The computing device identifies multiple sections within the captured data. Two or more sections represent respective iterations of the calibration sound as played by the playback device. Based on the multiple identified sections, the computing device determines a frequency response of the playback device, the frequency response of the playback device representing audio output by the playback device and acoustic characteristics of an environment around the playback device. Based on the frequency response of the playback device and a target frequency response, the computing device determines one or more parameters of an audio processing algorithm and sends, to the playback device, the one or more parameters of the audio processing algorithm.

An amplifier stage uses a loaded transistor amplifier circuit including a load that causes greater second order harmonic distortion energy than third order harmonic distortion energy to be produced in said loaded transistor amplifier circuit for amplifying a source audio signal to produce an audio output signal. The spectrum of the fundamental orders of harmonic distortion is adjusted to improve perceived sound quality or listening enjoyment.

A system, a sound processing method and a sound processing apparatus suitable for enhancing gamer experience for electronic games. The sound processing apparatus can communicate with a terminal suitable for playing an electronic game. The electronic game can be associated with audio data which can be communicated from the terminal to the sound processing apparatus. The sound processing apparatus includes a receive module for receiving the audio data and a processing module coupled to the receive module. The audio data can include low frequency range audio signals, mid frequency range audio signals and high frequency range audio signals. The audio data can be communicated from the receive module to the processing module. The processing module can be configured to process the audio data in a manner such that at least one of the low frequency range audio signals and the high frequency range audio signals are accentuated relative to the mid frequency range audio signals.

Certain embodiments provide methods and systems for managing a sound profile. An example playback device includes a network interface and a non-transitory computer readable storage medium having stored therein instructions executable by the processor. When executed by the processor, the instructions are to configure the playback device to receive, via the network interface over a local area network (LAN) from a controller device, an instruction. The example playback device is to obtain, based on the instruction, via the network interface from a location outside of the LAN, data comprising a sound profile. The example playback device is to update one or more parameters at the playback device based on the sound profile. The example playback device is to play back an audio signal according to the sound profile.

Embodiments described herein provide for smart configuration of audio settings for a playback device. According to an embodiment, while a playback device is a part of a first zone group that includes the playback device and at least one first playback device, the playback device applies a first audio setting. The embodiment also includes the playback device joining a second zone group that includes the playback device and at least one second playback device. The embodiment further includes the playback device applying a second audio setting based on an audio content profile corresponding to the second zone group.

A clock generator receives first and second clock signals, and input representing a desired frequency ratio. A comparison is made between frequencies of an output clock signal and the first clock signal, and a first error signal represents the difference between the desired frequency ratio and this comparison result. The first error signal is filtered. A comparison is made between frequencies of the output clock signal and the second clock signal, and a second error signal represents the difference between the filtered first error signal and this comparison result. The second error signal is filtered. A numerically controlled oscillator receives the filtered second error signal and generates an output clock signal. As a result, the output clock signal has the jitter characteristics of the first input clock signal over a useful range of jitter frequencies and the frequency accuracy of the second input clock signal.

Example techniques involve calibration of multiple playback devices. An example implementation receives, via a user interface of the network device, an input to initiate calibration of a group of playback devices comprising a first playback device and a second playback device configured to playback audio content in synchrony. After initiating the calibration of the group of playback devices, the implementation detects audio content rendered synchronously by the first playback device and the second playback device. Based on the detected audio content, the implementation determines a first equalization adjustment for the first playback device and a second equalization for the second playback device and causes the first playback device to apply the first equalization adjustment and the second playback device to apply the second equalization adjustment when the first playback device and the second playback device play audio content synchronously as part of the group of playback devices.