Yesterday the US Patent & Trademark Office published a series of six patent applications from Apple that relate to HomePod and possible future speaker systems and/or features.
1. Loudspeaker Orientation Systems # 20180352324
Patent Abstract: An audio system embodiment includes a loudspeaker cabinet having at least one loudspeaker transducer and defining a longitudinal axis. Several microphones are distributed around the longitudinal axis, defining an array of microphones. A reference microphone is positioned in the loudspeaker cabinet, e.g., in a rear chamber of the at least one loudspeaker transducer. The audio system includes a processor and a memory having instructions that, when executed by the processor, cause the audio system to receive an audio signal from each distributed microphone and the reference microphone, and therefrom to estimate a direction, relative to the plurality of microphones, of a nearby, acoustically reflective surface. Responsive to the estimated direction, the audio system affects a mode of operation, e.g., beam forms an audio output in a selected direction corresponding to the estimated direction of the acoustically reflective surface. Related principles are described by way of reference to exemplary embodiments. More
FIG. 2 illustrates an embodiment of an audio device (HomePod).
2. Audio Systems with Smooth Directivity Transitions #20180352325
Patent Abstract: An audio system includes a loudspeaker cabinet defining a longitudinal axis. Several loudspeaker transducers are distributed around the longitudinal axis. The audio system includes an audio rendering processor to cause the loudspeaker transducers to emit a sound field approximating a desired contour. The desired contour can be decomposed into a combination of several constituent modal beam components, and the audio rendering processor can render a truncated version of the decomposition to render an approximation of the desired contour. The desired contour can be one of a plurality of contours stored in a memory, or can be user defined. The cabinet includes a processor and a memory having instructions that, when executed by the processor, cause the audio system decompose a desired contour and to render a truncated version of the decomposition. Related principles are described by way of reference to method and apparatus examples. More
3. Loudspeaker Cabinet with Thermal and Power Mitigation Control Effort #20180352329
Patent Abstract: An operating power level for a loudspeaker cabinet and a target power level for the loudspeaker cabinet are determined during output of an audio signal by the loudspeaker cabinet. The target power level is based on temperature data for the loudspeaker cabinet and varies as the temperature data changes. Based on the operating power level and the target power level, values of two or more control parameters for controlling audio output of the loudspeaker cabinet are generated, where at least one of the control parameters controls the gain of a specific audio frequency band. The audio signal is adjusted according to the generated values of the control parameters, where doing so reduces power consumption of the loudspeaker cabinet during the audio output. More
4.Audio Adaption to Room #20180352333
Patent Abstract: An audio system includes one or more loudspeaker cabinets, each having loudspeakers. The system outputs an omnidirectional sound pattern to determine the acoustic environment. Sensing logic determines an acoustic environment of the loudspeaker cabinets. The sensing logic may include an echo canceller. A playback mode processor adjusts an audio program according to a playback mode determined from the acoustic environment of the audio system. The system may produce a directional pattern superimposed on an omnidirectional pattern, if the acoustic environment is in free space. The system may aim ambient content toward a wall and direct content away from the wall, if the acoustic environment is not in free space. The sensing logic automatically determines the acoustic environment upon initial power up and when position changes of loudspeaker cabinets are detected. Accelerometers may detect position changes of the loudspeaker cabinets. More
Apple’s patent FIG. 1 is a block diagram of a first audio system that embodies the invention
5. Spatially Ducking Audio Produced through a beamforming Loudspeaker Array # 20180352334
Patent Abstract: Apple’s invention covers a method for adjusting audio being outputted through a beam forming loudspeaker array. Program audio is rendered to drive the loudspeaker array to produce sound beams having i) a main content pattern that is aimed at a listener, superimposed with ii) several diffuse content patterns that are aimed away from the listener. In response to receiving an alert message that refers to alert audio, the portion of the program audio in the main pattern is moved into the diffuse patterns, and the alert audio is rendered to drive the loudspeaker array so that the portion of the program audio in the main pattern is replaced with the alert audio. More
Apple’s patent FIG. 2A above is a block diagram of an audio system having a beam forming loudspeaker array.
6. Acoustic Change Detection #20180352358
Patent Abstract: A loudspeaker cabinet has a number of pairs of microphones, each pair includes the same internal microphone and a different external microphone. For each pair of microphones, a process (i) receives a first audio signal of sound captured by the internal microphone and a second audio signal of sound captured by the different external microphone, (ii) estimates, using first and second audio signals, a radiation impedance, and (iii) computes a detection value based on the radiation impedance in a frequency band. A difference between (i) a currently computed detection value associated with a given pair of microphones and (ii) a previously computed detection value associated with said given pair, is computed. The sound produced by the cabinet is adjusted, in response to the computed difference meeting a threshold. More
Apple’s patent FIG. 2 shows a block diagram of an audio system having a sound output transducer and several microphones