---
title: "Send Audio Processing"
slug: "send-audio-processing"
updated: 2024-10-22T12:46:42Z
published: 2024-10-22T12:46:42Z
canonical: "docs.telosalliance.com/send-audio-processing"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.telosalliance.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Send Audio Processing

The Hx1 and Hx2 hybrid's send-to-caller audio processing consists of the following functions:

- Sample rate conversion
- High-pass filter
- Anti-Feedback, consisting of the “pitch” shifter and Acoustic Echo Canceler
- AGC/Limiter

### Sample Rate Conversion

AES and analog input sources are sample rate-converted to the hybrid’s internal sampling rate of 48 kHz.

### High-Pass Filter

A high-pass filter with a 300 Hz break frequency improves hybrid performance and enhances intelligibility by removing unnecessary low frequencies from the input audio. This filter is always enabled.

### Feedback Reduction

The Hx has an Acoustic Echo Canceler (AEC) that improves feedback performance and cancels echo caused by "speaker to mic" acoustic coupling. The Hx also uses a "frequency shifter" - a Telos Alliance innovation - that inserts a small, unnoticeable, shift in frequency to the send audio to prevent feedback buildup when the system is used with open speakers.

### Automatic Gain Control and Limiter

The AGC helps maintain consistent audio levels to the caller. This function is always enabled. At moderate levels, it is "AGC-like’" while at higher peak levels it is more "limiter-like". In addition to making levels more consistent to callers, it performs the protection limiting required to meet Telecom regulatory requirements.