In modern MacBooks, speaker systems must deliver high-quality audio within severe space and power constraints. Current designs operate within enclosure volumes under 100cm³, yet must reproduce frequencies from 60Hz to 20kHz while maintaining clarity at sound pressure levels above 85dB. The challenge is compounded by varying acoustic conditions as users move devices between different environments and orientations.

The fundamental engineering trade-off lies in balancing acoustic performance against the physical limitations of thin device profiles and thermal management requirements.

This page brings together solutions from recent research—including adaptive resonance control systems, moving magnet motor designs, real-time environment sensing, and pressure-management mechanisms. These and other approaches focus on maximizing audio quality while working within the strict dimensional and power constraints of mobile computing devices.

1. Audio System with Real-Time Resonant Frequency Detection for Speaker Output Control

Apple Inc., 2023

Adaptive resonance-controlled audio systems and methods for speakers in compact electronic devices to enhance loudness. The method involves determining the resonant frequencies of the speaker in real time based on measured electrical characteristics of the speaker component. The audio output is then generated at the determined resonant frequencies to provide loudness optimization. This ensures the audio is output at the speaker's resonant peaks rather than off-peak frequencies.

2. Speaker Occlusion Ejection via Real-Time Resonant Frequency Adaptation

Apple Inc., 2023

Adaptive resonance-based occlusion ejection for audio components like speakers in electronic devices. The technique involves determining the resonant frequency of the speaker based on electrical characteristics while it's occluded. Then, the speaker is operated at that resonant frequency to eject the occlusion. This is done in real-time as the speaker is occluded by water or debris to enhance loudness by optimizing output frequencies.

3. Moving Magnet Motor with Flux Concentrator for Loudspeakers

Apple Inc., 2023

Moving magnet motor for loudspeakers that reduces distortion and enables larger excursion compared to conventional moving magnet speakers. The motor has a closed magnetic circuit with a magnet and flux concentrator near the coil. The magnet and concentrator move together over the coil, focusing the magnetic flux density on the coil. This concentrates the flux density over the coil instead of passing through it, reducing reverse flux effects. This allows larger excursions without cancellation from opposite polarity flux. The concentrator follows the magnet's motion.

4. Transducer with Integrated Dual-Function Magnet Motor Assembly for Electroacoustic and Tactile Applications

Apple Inc., 2023

Dual function transducer that can be used as both an electroacoustic transducer (e.g., loudspeaker) and a tactile transducer (e.g., shaker). The transducer has a single magnet motor assembly that accommodates both the loudspeaker components (e.g., piston and voice coil) and shaker components (e.g., shaker coil) so that both functions can be achieved using a single transducer. The magnetic system design enables the utilisation of two functions by directing the magnetic field into two or more sets of high magnetic field density. One set is used by the vibration function, and the other set by the loudspeaker function.

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5. Multi-Driver Speaker System with Coordinated Cross-Channel Gain Reduction Mechanism

Apple Inc., 2023

A technique to improve perceived audio quality in multi-driver speaker systems by coordinated gain reduction across channels to prevent clipping and distortion. When a channel like the woofer is about to overload, instead of just limiting that channel, it also reduces gain on another channel like the tweeter to prevent overall sound from tilting towards the unlimited channel. This maintains a balanced response during loud playback.

6. Integrated Speaker Module with Moving Coil Woofer and Piezoelectric Tweeter

Apple Inc., 2023

A two-way integrated speaker system that combines a moving coil woofer and a piezoelectric tweeter into a single compact speaker module. The moving coil woofer generates low frequency sounds while the thin piezoelectric tweeter handles high frequencies. The piezoelectric tweeter uses piezoelectricity to convert electrical signals into vibrations. It has high resonance frequencies, low displacement, and generates no heat like coil speakers. By integrating the woofers and tweeters into a single module, it saves space compared to separate speakers.

7. Internal Speaker Enclosure with Rib-Supported Thin Walls and Opposing Phase Drivers

Apple Inc., 2023

Internal speaker design for thin electronic devices that maximizes speaker volume while minimizing enclosure thickness. The speaker enclosure has thin walls supported by internal ribs to prevent vibration. The speaker module is positioned within the device's internal volume and fluidly connected to the speaker enclosure. This allows the speaker volume to be increased without enlarging the enclosure. The speaker module can have multiple drivers with opposite diaphragm movement phases to provide full sound. The thin enclosure walls and compact design enable higher speaker volume in limited device spaces.

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8. Planar Magnetic Speaker Driver with Peripheral Conductive Traces and Central Diaphragm Clearance

APPLE INC., 2023

Planar magnetic speaker driver with improved central diaphragm motion and acoustic performance. The driver has conductive traces on the diaphragm that extend around a central region near the center. The traces are further outward on the perimeter. This allows the central region to be trace-free and radially inward from the magnets. This allows the diaphragm to deflect more in the center due to the wider gap there. It also enables acoustic radiation through the central opening without obstruction. This improves excursion and reduces distortion compared to covering the center with traces.

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9. Loudspeaker Back Volume Coating with Porous Zeolite Matrix Forming Convex and Concave Structures

APPLE INC., 2023

Coating the interior walls of a loudspeaker's back volume with a highly porous, acoustically active coating to improve sound quality. The coating contains a zeolite adsorbent and a binder that forms a porous, irregular matrix with connected convex shapes and concave connectors. The coating adsorbs and desorbs gases due to its porosity, which causes the back volume to behave as if it's larger than it actually is. This improves the speaker's low-frequency output without physically increasing the back volume size.

10. Audio Speaker with Dual-Cavity Back Volume Incorporating Expandable and Adsorptive Fillers

APPLE INC., 2022

An audio speaker design with expandable fillers in the back volume to improve loudspeaker performance. The speaker has a permeable partition dividing the back volume into two cavities, a rear cavity behind the driver and an adsorption cavity. An expandable filler expands when triggered to reduce membrane vibration forces. An acoustic filler of adsorbing beads in the adsorption cavity absorbs back volume pressure fluctuations. This dual-filler configuration reduces back volume effects on sound quality without increasing the physical size of the speaker.

11. Speaker Assembly with Multiple Nested Helmholtz Resonators and Independent Frequency Response Chambers

Apple Inc., 2022

Speaker design with multiple nested Helmholtz resonators to improve frequency response and fluid resistance in compact devices. The speaker has a front volume bounded by a housing wall and a frame. Nested resonator chambers are formed by recesses in the frame and separate from the back volume. A first resonator chamber has an entry port in the housing wall. A second resonator chamber is inside the first chamber and has its own entry port. This allows independent frequency response optimization for each resonator.

12. Speaker Assembly with Vented Resonator and Ported Chamber for Enhanced High-Frequency Performance

Apple Inc., 2022

Speaker design with a vented resonator to improve high-frequency response in compact electronic devices. The speaker has a front volume, back volume, diaphragm separating them, and a vented resonator between them. The resonator has a port to the front volume, a chamber, and a vent between the chamber and back volume. This allows airflow between the volumes through the resonator instead of directly between the front and back volumes. It reduces front volume size and shortens output path length to improve high-frequency response.

13. Spatial Audio System with Dynamic Head-Tracking and Adaptive Binaural Room Impulse Responses

APPLE INC., 2022

Spatial audio reproduction with head-tracking and binaural room impulse responses (BRIRs) that have built-in reflection patterns. The BRIRs are generated continuously based on the user's head position and a set of head-related impulse responses (HRIRs) representing acoustic reflections. This allows spatialized sound with customizable reverberation characteristics that follow the user's head movements. The BRIRs approximate the room reverberation by simulating reflections with directions, delays, and equalization to match the actual room's acoustics.

14. Vented Acoustic Transducers with High-Aspect-Ratio Tortuous Path Impedance Channels

Apple Inc., 2022

Vented acoustic transducers like microphones and speakers that equalize barometric pressure across the diaphragm to prevent damage from large pressure swings. The vents have complex acoustic impedance to equalize low-frequency pressure variations while inhibiting higher-frequency pressure variations that can excite the diaphragm. The vents are high-aspect-ratio, elongated channels with tortuous paths through the device. They can also be segmented with acoustic mass and compliance sections. These vents provide equalization without leakage noise.

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15. Speaker Suspension with Stretchable Conductive Biphasic Materials for Electrical Connection and Integrated Strain Sensing

Apple Inc., 2021

Speaker design with improved reliability and sensing capability by using stretchable conductive biphasic materials in the suspension to electrically connect the voice coil to the terminals instead of lead wires. The biphasic material has a solid component like gold-gallium alloy and a liquid component like gallium deposits. This allows the voice coil to move without breaking the electrical connection. The biphasic material can also have strain sensors embedded to detect diaphragm displacement.

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16. Loudspeaker Acoustic Noise Mitigation via Predictive Signal Analysis and Volume Adjustment

Apple Inc., 2020

Mitigating loudspeaker-induced acoustic noise in audio devices like laptops to improve overall sound quality by reducing audible noise only when it exceeds the desired sound level. The method involves analyzing the audio signal using a device model to predict the noise level at the listener's position. If the predicted noise exceeds the desired sound level, the device reduces the loudspeaker volume to lower the noise without impacting the desired sound.

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