Sound Reinforcement

Sound Reinforcement Package

Introduction

Sound Reinforcement Package (SRP) is an ultra-low-latency DSP and DNN package designed for real-time voice reinforcement in acoustically challenging environments.

It combines adaptive microphone processing, deep neural network noise and reverberation reduction, echo and feedback cancellation, and advanced dynamic range control into a single, coherent signal chain optimized for speech clarity and stability.

SRP integrates and benefits from Alango proprietary Zero Latency Signal Processing (ZLSP) technology enabling a sub-millisecond system latency while fully utilizing the benefits of Deep Neural Network based technologies with high frequency resolution.

SRP is suitable for stationary indoor and outdoor sound reinforcement systems such as classrooms, lecture halls, auditoriums, meeting spaces, kiosks, and portable PA systems, where intelligibility, gain-before-feedback, and minimal latency are critical.

Block Diagram

Technologies

Adaptive beamforming with dual or multi-microphone arrays focuses on the active talker while attenuating side and rear interferers. This improves signal-to-noise ratio and remains effective as speaker position or acoustic conditions change.

DNN-based noise reduction attenuates stationery, transient, and non-stationary noises while preserving speech details. Allows up to 40 dB noise attenuation with high frequency resolution, low distortion and ultra-fast adaptation (~50 ms).

Reverberation suppression emphasizes direct speech and attenuates reflected acoustic energy, improving intelligibility and listening comfort in reflective spaces such as rooms with hard surfaces, large halls, or semi-outdoor installations.

AEC removes playback from microphone signals isolating the user's voice for clean recording, scoring, or communication in "hybrid" systems where voice is mixed with music (e.g., in-car karaoke). Fast convergence ensures stable performance and clear vocal capture even in noisy or changing acoustic environments.

Feedback cancellation prevents howling between microphones and loudspeakers by continuously detecting and suppressing feedback paths. Sub-band adaptive filters, frequency shifting, a proprietary phase decorrelation technique and intelligent feedback suppressor enable significant additional gain-before-feedback, even when system geometry, volume or feedback path changes.

Multi-band dynamic range control shapes speech dynamics across multiple frequency bands, delivering consistent loudness and improved intelligibility. Configurable 2–24 sub-bands (typ. 5–16); per-band compression curves using six configurable points (knees) per band for shaping.

Spectral shaping enhances speech articulation by selectively and dynamically emphasizing consonant energy and balancing the speech spectrum. This improves clarity, especially at lower playback levels or in noisy environments.

Supporting DSP elements such as filtering, DC removal, delay compensation, and signal alignment stabilize the processing chain and support accurate system tuning.

SRP is optimized for real-time voice reinforcement with very low algorithmic latency 6 ms (@2 ms frame) / 3 ms (@1 ms). This results in preserved lip-sync and minimizing comb-filtering effects caused by direct acoustic leakage.

The Sound Reinforcement Package (SRP) is designed to support both localized voice amplification and complex bi-directional communication by adapting its processing to the specific feedback and echo challenges of either.

• One-Way (Local Reinforcement): Optimized for PA and public address applications where the objective is clear voice amplification within a physical space. This mode leverages the Acoustic Feedback Canceller (AFC) to maximize stable gain-before-feedback, preventing "howling" even at high volume levels.
• Two-Way (Interactive Communication): Enables full-duplex operation for intercoms, in-car communication, and hybrid reinforcement scenarios. This mode integrates Acoustic Echo Cancellation (AEC) to remove remote playback far speech and audio from the microphone signal while the AFC maintains local stability, allowing for natural, simultaneous speech without echoes or instability.

Integration

SRP runs on a wide range of DSPs and application processors, including ARM-based platforms, Cadence Tensilica HiFi cores and RISK-V. It’s been successfully integrated into selected Bluetooth and application SoCs. Additional platforms can be supported on request.

A Windows-based configuration and tuning tool is provided to simplify system setup, optimization, and fine-tuning across different microphones, loudspeakers, and acoustic environments.

Applications

Educational & Corporate:
Classrooms, lecture halls, auditoriums, and meeting spaces where high speech intelligibility is critical.

Public Infrastructure:
Indoor and outdoor stationary sound reinforcement, including information kiosks and help points.

Mobile & Event Audio:
Portable PA systems and tour guide equipment requiring rapid setup and stable gain.

Multimedia & Hybrid Systems:
Voice-plus-music reinforcement
(e.g., in-car karaoke, infotainment)
and interactive two-way communication systems.

Videos