1. Challenge Description

The Music Demixing (MDX) Challenge is an opportunity for researchers and machine learning enthusiasts to test their skills by creating a system able to perform audio source separation. Such a system, given an audio signal as input (referred to as “mixture”), will decompose it in its individual parts.

The Music Demixing Challenge (MDX) will focus on music source separation and it follows the long tradition of the SiSEC MUS challenges. Participants will submit systems that separate a song into four instruments: vocals, bass, drums, and other (the instrument “other” contains signals of all instruments other than the first three, e.g., guitar or piano).

2. Sponsors

The Challenge is organized and sponsored by Sony Group Corporation (SGC). This will be referred to as “Organizers'' collectively from here on.

3. Organizers Admins

“Organizers Admins” are any companies or organizations authorized by Organizers to aid them with the administration or execution of this Challenge including but not limited to AIcrowd SA.

4. Challenge Start and End Dates

There will be two rounds of submissions in total (1st round: May 3rd – June 13th; 2nd round: June 14th – July 31st).

The dataset is split into 3 parts of 9 songs each. During the first round, participants will only see their scores on the first split, i.e. 9 songs of the hidden test set. During the second round, participants will only see their scores on the 1st and 2nd split, i.e. 18 songs of the hidden test set. The final leaderboard and the winning of prizes will be based on the scores on the full hidden test set of 27 songs.

The challenge starts May 3rd 2021 12:00PM UTC and ends July 31st 2021 12:00PM.

5. Am I Eligible to Enter the Challenge?

You are eligible to enter this Challenge if you (and each member of your Team) meet all of the following requirements as of the time and date of entry:

  • You are an individual;

  • You are 18 years of age or older but in no event less than the age of majority in your place of residence;

  • You have Internet Access, an Email Account, and access to a personal computer;


The organizers admins will not be able to transfer prize money to accounts of any of the following countries or regions. (Please note that residents of these countries or regions are still allowed to participate in the challenge.)

  • The Crimea region of Ukraine

  • Cuba

  • Iran

  • North Korea

  • Sudan

  • Syria

  • Quebec, Canada

  • Brazil

  • Italy

Please Note: it is entirely your responsibility to review and understand your employer’s and countries policies about your eligibility to participate in this Challenge. If you participate in violation of your employer’s or countries policies, you and your Entry may be disqualified from the Challenge. Organizers disclaim any and all liability or responsibility with respect to disputes arising between an employer and such employer’s employee or between a country and its resident in relation to this matter.

6. Is the Entry an Eligible Entry?

To be eligible to be considered for a prize, as solely determined by the Organizers:

The Entry MUST:

  • be compatible with the official submission format;
  • be in English;

  • be the Team’s own original work;

  • not have been submitted previously in any promotion of any kind;

  • not contain material or content that: is inappropriate, indecent, obscene, offensive, sexually explicit, pornographic, hateful, tortious, defamatory, or slanderous or libelous; or promotes bigotry, racism, hatred or harm against any group or individual or promotes discrimination based on race, gender, ethnicity, religion, nationality, disability, sexual orientation, or age; or promotes alcohol, illegal drugs, or tobacco; or violates or infringes another’s rights, including but not limited to rights of privacy, publicity, or their intellectual property rights; or is inconsistent with the message, brand, or image of Organizers, is unlawful; or is in violation of or contrary to the laws or regulations of any jurisdiction in which the Entry is created; and

The Team members MUST:

  • ensure the Team has obtained any and all consents, approvals, or licenses required for submission of the Entry;

  • obtain any consents necessary from all members of the Team with respect to the sharing of such member’s personal information as outlined herein;

  • obtain the agreement of all members of the Team to these Rules;

  • not generate the Entry by any means which violate these Rules, the Organizers Terms of Service or the Organizers Privacy Policy;

  • not engage in false, fraudulent, or deceptive acts at any phase during participation in the Challenge; and

  • not tamper or abuse any aspect of this Challenge.

7. Disqualification

  • If you, any Team member, or the Entry is found to be ineligible for any reason, including but not limited to conflicts within Teams and noncompliance with Sections 5 and 6 of these Rules, Organizers and Organizers Affiliates reserve the right to disqualify the Entry and/or you and/or your Team members from this Challenge and any other contest or promotional activity sponsored or administered in any way by the Organizers.

  • A participant is not allowed to create more than one account to participate in the challenge. Violating this will result in disqualification from the challenge.

8. How may the Entry potentially be used?

The Entry may be used in a few different ways. Organizers do not claim to own your Team’s Entry, however, by submitting the Entry you and each member of your Team:

  • hereby grants to Organizers Admins a non-exclusive, irrevocable, royalty-free, world-wide right and license to review and analyze the Entry in relation to this Challenge;

  • hereby grants to Organizers and Organizers Admins a non-exclusive, irrevocable, royalty-free, world-wide right and license to use the Entry or parts of your Entry in any media for any non-commercial or commercial purpose in connection with the marketing, sale, or promotion of Organizers, Organizers Admins and their respective products and services;

  • agrees that each member will execute any necessary paperwork for Organizers and Organizers Admins to use the rights and licenses granted hereunder;

  • acknowledges and agrees that the Team will not be compensated and may not be credited (at Organizers’s sole discretion) for the use of the Entry as described in these Rules;

  • acknowledges that the Organizers or Organizers Admins may have developed or commissioned materials similar to the Entry and waive any claims resulting from any similarities to the Entry;

  • understand that the Entry may be posted on a public website or social media channel and that Organizers is not responsible for any unauthorized use of the Entry by visitors to such site; and

  • understand and acknowledge that, subject to provision of Prizes, Organizers are not obligated to use the Entry in any way, even if the Entry is selected as a winning Entry.

Personal data you submit in relation to this Challenge will be used by Organizers and Organizer Admins in accordance to Section 15 of these Rules.

9. How will Winners be Selected and Notified?

Entries will be judged via an algorithm that will generate a score based upon which Entries will be ranked and such ranking will be displayed on the AIcrowd Site’s Challenge specific leaderboard (“Leaderboard”). There are two leaderboards – one for systems that were solely trained on the training part of MUSDB18HQ (“Leaderboard A”) and one for systems trained on any data (“Leaderboard B”).

In each round the algorithm will rank your Entry using a hidden test set. As evaluation metric, we are using signal-to-distortion ratio (SDR), which is defined as

is the waveform of the ground truth and sinstr(n) denotes the waveform of the estimate. The higher the SDR score, the better the output of the system is.

In order to rank systems, we will use the average SDR computed by

for each song. Finally, the overall score SDRtotal is given by the average over all songs in the hidden test set. There will be a separate leaderboard for each round.

For an academic report about the challenge, the organizers will get access to the separations of the top-10 submitted entries (i.e., their output) for each leaderboard in order to compute more source separation metrics (e.g., signal-to-interference ratio).


Tied Entries

If two or more participating Teams have the same score, a secondary algorithmic metric will be added to the scores. If all scores are identical and prizes are awarded to the teams they will be shared evenly among the Teams.

Potential winners will be contacted within one week of each Deadline via the email associated with AIcrowd.com account through which the Entry was submitted. If a potential winner cannot be contacted, does not respond as directed, refuses the prize, or is found to be ineligible for any reason, such prize may be forfeited and awarded to an alternate winner. Only one alternate winner will be selected per each prize package, after which prizes will remain unawarded.

To be eligible for the prizes, participants will have to release the code to their solutions under an open-source license of their choice with a proper documentation. The submitted code is expected to be reproducible and should produce a similar score as on the leaderboard.

To the extent that there is any dispute as to the identity of the potential winner, the official account holder of the email address associated with the AIcrowd account through which the Entry was first submitted will be deemed the official potential winner by Organizers.

10. Your Odds of Winning


11. Prizes

The total prize pool is 10,000 CHF, which will be divided equally among the two leaderboards.

Leaderboard A

  • 1st Prize: 3500 CHF

  • 2nd Prize: 1000 CHF

  • 3rd Prize: 500 CHF

Leaderboard B

  • 1st Prize: 3500 CHF

  • 2nd Prize: 1000 CHF

  • 3rd Prize: 500 CHF

12. When will prizes be awarded?

The prizes will be awarded within a commercially reasonable time frame. All members of a Team may be required to complete and sign additional documentation, such as non-disclosures, representations and warranties, liability and publicity releases (unless prohibited by applicable law), and tax documents, or other similar documentation in order for the potentially winning team to claim the prize. Organizers will in no way be involved in any dispute with respect to receipt of a prize by any other members of a Team.

Only prizes claimed in accordance to these Rules will be awarded.

13. Winner List

A list of all winners of this Challenge will be posted on AIcrowd Site and may be announced at Organizers’ discretion via Organizers’ Twitter, Facebook, Blog, or Website, or at an Organizer or Organizer Admins sponsored or hosted event.

14. Your Personal Data and Privacy

Organizers may use cookies and/or collect IP addresses for the purpose of implementing or exercising its rights or obligations under the Rules, for information purposes, identifying your location, including without limitation for the purpose of redirecting you to the appropriate geographic website, if applicable, or for any other lawful purpose in accordance with the Privacy Policy.

Organizers may use the personal data you provide via your participation in this Challenge:

  • to contact you in relation to the Challenge;

  • to confirm the details of your Entry;

  • to administer and execute this Challenge, including sharing it with Organizer Admins;

  • at Organizers’ discretion, to credit you and/or your Team for the Entry, identify you and/or your Team as a Winner, or other similar notice; and

  • as otherwise noted in these Rules or as necessary for Organizers to meet their obligations under these Rules or applicable law.

Organizers only require name and email address to be submitted for you to participate in this Challenge for its uses as outlined in this Section 15.

Please read the terms and conditions of the AIcrowd Site carefully to understand how your data may be used by AIcrowd SA.

15. Additional Terms and Conditions

If Organizers determine, in their sole discretion, that any portion of this Challenge is compromised by virus, bugs, unauthorized human intervention, or any other causes beyond its control, that in the sole opinion of Organizers corrupts, or impairs the administration, security, fairness or proper participation in/of the Challenge, Organizers reserves the right to (a) cancel the Challenge; (b) pause the Challenge until such time the aforementioned issues may be resolved; or (c) consider only those Entries submitted prior to the when the Challenge was so compromised for the prizes.

To the fullest extent permitted by applicable law, you agree that Organizers, Organizer Affiliates, and Organizer Admins, and each of their directors, officers, employees, agents and assigns, will not be liable for personal injuries, death, damages, expenses or costs or losses of any kind resulting from participation or inability to participate in this Challenge or acceptance of or use or inability to use a prize or parts thereof including, without limitation, claims, suits, injuries, losses and damages related to personal injuries, death, damage to or destruction of property, rights of publicity or privacy, defamation or portrayal in a false light (whether intentional or unintentional), whether under a theory of contract, tort (including negligence), warranty or other theory.

Your use of any other products and services required by these Rules, whether required by these Rules or not, are subject to the terms and conditions associated with such products or services, including the AIcrowd site and services.

In the event any clause or provision of these Rules prove unenforceable, void or incomplete, the validity of the other conditions will remain unaffected.