Audio restoration
Audio restoration
Noise suppression

Whether you’re a new user or a professional audio expert, Sound Cleaner II audio restoration software has the necessary tools for a full range of noise suppression and speech enhancement tasks.

Sound Cleaner II, with its newly overhauled user interface, gives you high-performance intuitive tools for best results. Powerful noise filters and other special features help you deliver results faster than ever.


Broadband noise filter

Broadband Noise Filter

The broadband noise filter is designed to suppress background noise from the room or the street and interference from communication channels or recording equipment. These noises come across as hums, rumbling, hisses or roars. Other methods don’t remove these noises effectively because they’re spread across the entire spectrum, intersecting with the speech signal. The broadband noise filter algorithm automatically adapts to the changing noise floor, so it doesn’t need to be trained, offering a unique combination of efficiency and simplicity. 

Inverse filter

Inverse Filter

Inverse filtration effectively suppresses strong periodic noises from electrical pick-ups and mechanical vibrations, recovering the speech signal and equalizing its frequency response. It amplifies weaker signal components while suppressing stronger ones. The average spectrum therefore tends to approach the flat spectrum, unmasking the speech signal and improving its intelligibility.

Tone suppressor

Tone Suppressor

The tone suppressor filter is most effective for narrow-band stationary and harmonic interferences, including power supply hum, slow melodic music and sirens and drones of all kinds. Instead of erasing the noise frequencies from the spectrum, the tone suppressor uses “smart” methods to detect and subtract them. The result is better speech quality than that provided by other filters. 

Click suppressor

Click Suppressor

The click suppressor restores audio fragments distorted by various pulse interferences, such as clicks, old vinyl crackles, radio noises and short pops. The algorithm automatically detects, suppresses and substitutes impulses with smoothened and weakened interpolated signals. Fragments without clicks stay intact. 

Dynamic range control

Dynamic Range Control

With dynamic range control, you can amplify weak signals to balance the level of speech between two speakers or weaken them to suppress noise in pauses between loud speech fragments. 

2048-band graphic EQ


A 4096-band graphic EQ combined with a spectrum analyzer is used to do precise spectral corrections of distorted audio signals. The EQ is supplied with a wealth of options, including automatic filters, the ability to use and create presets, input and output spectra display and linking sliders for simultaneous control. The Sound Cleaner EQ is an indispensable tool for a wide scope of restoration and enhancement challenges.  

Reverb suppressor

Reverb Suppressor

Sound Cleaner II’s unique reverb suppression algorithms decrease reverberations to raise speech signal intelligibility and reduce listener fatigue. Reverberated signals are interpreted as resonant, indecipherable speech. The signals aren’t masked by additional noises, but become distorted themselves. This complicates the enhancement task and makes the reverb suppressor a valuable asset. 

DTMF suppressor

DTMF Suppressor

The DTMF filter targets phone dialing sounds. Despite their tonal nature, these noises can’t be effectively suppressed with tonal filters because of their short duration. That’s where the DTMF suppressor comes in handy. 

Cellphone Noise Filter

Audio recording devices easily pick up interference from incoming cell phone calls. Sound Cleaner II’s new dedicated Cellphone Noise Filter attenuates these pick-ups.  

Clip restorer

Clip Restorer

When a signal’s amplitude exceeds the recording device’s dynamic range, the waveform is clipped and the sound appears distorted. The clip restorer algorithm detects and restores clipped fragments by reconstructing lost information. 

STC Auto filter

STC Auto filter

Novice audio experts will enjoy auto filter. This single control is used to alleviate the most commonly encountered noises.

Reference noise filter

Reference noise canceller

The backbone of these methods is acquiring the information about the interference from the reference channel and using it to remove this interference from the primary channel. The reference noise might be presented as a TV, radio or music playing in the background. The new sync function allows receiving reference channel separately from the main channel. It might be recorded on apart from main channel or downloaded from the Internet. Ideal sync of reference and main channel is a must precondition for successful filtering. Now this operation is done automatically to provide users with the best results.

What's new

Sound Cleaner II

Sound Cleaner upgrade is here!

Since its first release 20 years ago, Sound Cleaner has grown in popularity across the international audio forensic community for its simplicity and effectiveness—even in the most challenging cases.
We are now pleased to announce the release of Sound Cleaner II, the newest version of this AES award winning audio enhancement software. In addition to bringing Sound Cleaner users new essential noise filters and other exciting features, almost every aspect of the program has been rethought and redesigned.

Even with the upgrade, Sound Cleaner II maintains the structural and meaningful core of its forerunners. Users can design their own signal processing procedures, combining any of the filters provided in the desired processing sequence. Upon completion of a given filtering process, that filter transmits a signal to the subsequent process. After that algorithm is applied, the processed signal is passed on to the next module in the chain. The number of modules used in a single chain is limited only by hardware capabilities (PC or workstation). Filtering results are immediately available for viewing and listening. 

 Noise suppression

More filtering capabilities

Sound Cleaner II offers new filtering capabilities. Get rid of cellphone pick-ups and DTMF dialing beeps with the new Cellphone Noise Filter and the new DTMF Suppressor. Restore clipped audio with the new Clip Restorer. Novice audio experts will enjoy Auto Filter. This single control filter can be used to alleviate the most commonly encountered noises.

Easy navigation

The functional waveform navigation bar lets you see the entire signal. The area being analyzed is displayed in the waveform navigation window. This can be easily changed by selecting another section for display.

Full control over processing history

Every action that modifies the signal is logged in the history tab and made available for undo/redo.

Text report

Professional activity reports

Sound Cleaner II generates professional reports featuring your company logo and contact information, audio file information, a log of filters applied and their settings, as well as all signal changes. Screenshot tools let you enhance your report with input and output waveforms and spectra.

Working with projects

Saving a file as a project lets you keep the filtering sequence, text transcripts and modification history for further use.

Create forensic transcripts

Sound Cleaner II built-in text editor links text to audio for quick reference.

 Noise filtering

Sync reference and main channel for filtering
Sound Cleaner II new audio sync algorithm revolutionizes reference noise filtering by recording a mono reference channel separately from main channel.

Widest range of audio formats supported

Sound Cleaner II extracts audio tracks from video files in virtually any format and codec.

VST3 support

All Sound Cleaner II filters are available from any DAW as a VST plug-in.

Support and Resources

Contact Sound Cleaner II product specialist:

E-mail: stc-int@speechpro.com

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Video Tutorials

Sound Cleaner II Overview

System Requirements

Operating system requirements:

Windows 7, 8 or 10 (32-bit and 64-bit)

The development and maintenance of software version for Mac OS is stopped since 03.2018.

Plug-in formats:


Supported audio formats:

wav, aiff, mp3, wma, flac, ogg, avi, mov, flv, and many more


White paper







How to register


  1. Launch Sound Cleaner II and click Activate
  2. As you redirected to the online activation page enter your product key to log in. Fill out the form and click save
  3. Click the Online Activation button and your copy of the software will be activated.


  1. Launch Sound Cleaner II and click Activate offline
  2. As a special utility is launched click Collect Information
  3. Copy a created file with c2v extension to the flash memory and bring it to the computer with Internet access
  4. Go to the web page http://activation.speechpro.com:8080/ems/customerLogin.html
  5. Enter your product key to log in. Fill out the form and click save
  6. Click the Offline Activation button
  7. Copy a created file with v2c extension to the flash memory and bring it back to the computer where c2v file has been generated
  8. Launch Sound Cleaner II and click Register offline
  9. Switch to Apply License File tab in the window
  10. Browse for your v2c file and click Apply Update button to apply license update to your key
  11. After a complete product registration you will see the software’s main window.


Boxed version comes in a software hard box that contains a DVD and a hardware license key, a dongle. The dongle allows easily transferring the license to another computer.

Electronic download comes as a download link and a registration key to your e-mail. The software can be activated on one computer only.

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Demo version limitations.

Demo version will be available for evaluation within 30 days since the first start. It is fully functional and offers the same noise reduction capabilities as the retail version. Please note that the demo version cannot run under a Virtual Machine.

Sound Cleaner II Sound Cleaner II
Sound Cleaner II Sound Cleaner II

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Demo samples



I had reviewed the “SoundCleaner” software demo from SpeechPro and was considering purchasing the product. I recently had an occasion to see a registered program demonstrated and was taught the basic use of the software. I bought it on the spot! I now use it as my primary noise processing program and find it one of the most useful software packages I have for forensic work. It is both complex and simple at the same time. The tools used individually or in combination provide a powerful processor that does what it claims.

As I become more adept at using “SoundCleaner”, I believe that its power will become even more evident. I love it!

Skip Frazee, owner
Forensic Sound

I have been using “Sound Cleaner” for three weeks and I have found it to be an extraordinary program for eliminating background noise and improving the intelligibility of audio signals. In the short time I have had the program I have been able to achieve outstanding results with a minimal learning curve. I look forward to future developments form Speech Technology Center.

Robert Rosen
Rosen Audio Rescue

I have been using “Sound Cleaner” since it was first available in the United States and find it the best tool for tape enhancement and audio restoration available. I have tried almost all the hardware and software solutions and now “Sound Cleaner” is always my first choice.

Richard W. Sanders
Associate Professor at the University of Colorado at Denver (UCD)

I have been working in the field of forensic audio analysis for the past twenty-two years dealing with audio authentication, enhancement and sound and voice identification. My clients include private citizens, defense attorneys, law enforcement agencies and major airline companies. In the area of audio enhancement, my work ranges over a wide expanse of audio noise problems, including the enhancement of speech recordings as well as non-speech signal enhancement. Audio enhancements are always a challenge to fine the exact line between noise reduction and optimal speech signal intelligibility. Over the years I have worked with many analog and digital enhancement processors. I find that since the addition of “Sound Cleaner” to my enhancement tools, I am turning to it as the tool of first choice. “Sound Cleaner” allows me to quickly attenuate the noise and bring up the intelligibility of the speech signal. The convenience of chaining together a wide variety of powerful enhancement filters into one neat package combined with the real-time adjustments make this program indispensable. I would recommend “Sound Cleaner” to anyone who is serious about audio enhancement.

Michael C. McDermott
Certified Forensic Audio Expert

"Sound Cleaner” is an essential tool for sonic enhancement and noise removal. The unique assortment of filters yield fantastic results without the hassle associated with other software programs."

Barry Dickey
Audio Evidence Lab

I would like to take this opportunity to congratulate you on winning the Audio Engineering Society’s Enhancement Contest at the 33rd International Contest held recently in Denver, Colorado. I have utilized the software to: clarify the transcript in the John Gotti Jr. trial 2006, clarify the Wead – President Bush Tapes and clarify Frank Sinatra’s very first recording.

Tom Owen
Owl Investigations Inc.