NOISE REDUCTION VOICE QUALITY ENHANCEMENT ALGORITHM

Telephony by Adaptive Digital

ADT NOISE REDUCTION Voice Quality Enhancement Software

DESCRIPTION

The Adaptive Digital noise reduction software reduces background noise in speech signals. Applications include traditional, mobile, and hands-free telephone systems, conferencing, speech recognition, and alarm systems. The algorithm can be customized to trade off between complexity, memory requirements, and required noise reduction. 

Data sheet:.pdf

  1. CPU Utilization
  2. Memory Utilization
  3. Algorithmic Delay
  4. Ability to cancel noise in the presence of signal. (SNR Improvement). If the algorithm does not cancel noise in the presence of signal, it only reduces noise when desired signal (speech) is not present as is the case between speech bursts.
  5. Frequency Domain Based vs. Time Domain Based

Adaptive Digital has two classes of noise reduction algorithms . They are distinguished by a number of characteristics. We refer to the two classes of noise reduction algorithms as the standard version and the low complexity version. The table below compares the characteristics of the two versions.

Algorithm Version CPU Utilization Memory Delay SNR Improvement Frequency / Time Based
Standard High High Moderate Yes Frequency
Low Complexity Low Low None No Time

The user can configure either version’s noise cancellation to be more or less aggressive. Less aggressive settings reduce noise by a moderate amount while more aggressive settings reduce noise by a greater degree.

One might wonder why a system would be configured with a less aggressive setting. There are a few reasons. One reason is that a very aggressive setting can result in loss of desired signal. Another reason is that, in the case of the low complexity version, an aggressive setting will cause an accentuated difference between the noise level during speech and the noise level when speech is not present. The transitions between speech and no speech may become more objectionable with the more aggressive setting.

APPLICATIONS

Standard noise reduction is an excellent choice for applications with high background noise environments such as mobile phones, speakerphones, hands-free phones, and defense communication systems. It is also useful when used in conjunction with voice recognition to increase accuracy.

Low Complexity noise reduction is an excellent choice for wireline telephony and conferencing.

FEATURES

  1. User configurable

  2. Enhances Voice Quality (improves Mean Opinion Score)

  3. Functions are C-callable

  4. Designed for multiple channel operation

AVAILABILITY

ADT Noise Reduction is available on the TMS320™ DSP Family

C54x™DSP, C55x™DSP, & C64x™DSP Generations

ARM Processor

SPECIFICATIONS

Noise Reduction C54x

All Memory usage is given in units of 16-bit word.
Variant MIPS (Peak) Program Memory Data Memory Per Channel Data Memory
Standard 7.5 2272 155 750

Noise Reduction C55x

All Memory usage is given in units of byte.
Variant MIPS (Peak) Program Memory Data Memory Per Channel Data Memory
Standard 7.5 4500 310 1500

Noise Reduction C64x

All Memory usage is given in units of byte.
Variant MIPS (Peak) Program Memory Data Memory Per Channel Data Memory
Standard 7.4 10400 1384 1500

Noise Reduction ARM

All Memory usage is given in units of byte.
Variant MIPS (Peak) Program Memory Data Memory Per Channel Data Memory
Standard 37 10400 1384 1500

 

FUNCTION

NCAN_ADT_config( . . .) Configures Noise Canceller

NCAN_ADT_init( . . .) Initiates a channel of Noise Cancellation

NCAN_ADT_cancel( . . . ) Executes Noise Cancellation


APPLICATIONS

Standard noise reduction is an excellent choice for applications with high background noise environments such as mobile phones, speakerphones, hands-free phones, and defense communication systems. It is also useful when used in conjunction with voice recognition to increase accuracy.

Low Complexity noise reduction is an excellent choice for wireline telephony and conferencing.