Abstract: Systems and methods are disclosed for providing portable device presence utilizing environmental ambient audio fingerprints. Portable devices provide media exposure data and environmental ambient fingerprints to a processing device, where the environmental ambient signatures provide at least one characteristic of the ambient audio surrounding each portable device. The environmental ambient signatures are then processed to determine if they match. Portable devices associated with matching signatures are identified. Ambient fingerprints may also be used to establish a logical location where media exposure took place. The ambient signatures are alternately combined with monitored data to provide more robust data sets for contextual processing.

Abstract: A method and apparatus are provided for matching an output of an auxiliary signal transducer with a reference signal transducer where the auxiliary signal transducer and reference signal transducer receive audio signals from a common signal source along different respective signal paths. The method includes the steps of determining a signal amplitude output value provided by the auxiliary and by the reference transducers within each of a plurality of different frequency ranges in response to the audio signal received along the respective signal paths and adjusting the signal amplitude output value of the auxiliary transducer within at least some of the plurality of different frequency ranges based upon the respective signal amplitude output value of the reference transducer.

Abstract: An acoustic apparatus comprises a cabinet, and a loudspeaker unit and a driving apparatus disposed in the cabinet. The acoustic apparatus is driven by an external power amplifier which normally constant-voltage-drives a conventional loudspeaker. The driving apparatus has a power amplifier circuit and a transfer function control circuit, and drives the loudspeaker unit in cooperation with the external power amplifier. The driving apparatus generates an electric energy corresponding to an increase in energy from that which is required in a normal constant-voltage-driving, the increase being produced by an operation of the transfer function control circuit, and the generated energy is inputted to the loudspeaker unit.

Abstract: In order to obtain for electrodynamic loudspeakers, on the one hand, the energy-favorable acoustical enhancement by the bass reflex principle and, on the other hand, to be able to use the motional control of the diaphragm of the electrodynamic loudspeaker by controlling such by means of an amplifier exhibiting negative output impedance, it is proposed to compensate the thus resulting unfavorable frequency characteristic by a forwardly connected circuit which generates an inverse characteristic with respect to the unfavorable frequency characteristic.

Abstract: For improved sound reinforcement, especially of the human voice, in situations where clarity and full audience coverage are important, an integrated structure supports a microphone and a speaker unit in an anti-feedback spatial relationship. The single speaker unit, mounted in an elevated position facing the audience, acts as a well-localized "point source", the microphone being located nearby in a working location to the rear of speaker. Despite this proximity, acoustic feedback and resultant "howl" tendencies are suppressed by providing both the microphone and the speaker unit with hypercardioid directivity and locating them in an offset back-to-back relationship such that alignment of their "null" regions combines their attenuation, minimizing feedback. In one embodiment, a lectern table supports the microphone in a working position and mounts an offset vertical pole carrying the speaker unit. The system amplifier may be housed within the lectern table.