Dear Arijit,That's an excellent point. As of yet, I haven't come across any studies directly investigating that specific comparison. However, the development of MUSHRA likely included such an evaluation. The method is defined in ITU-R Recommendation BS.1534-3. The introduction states:
"This Recommendation describes a method for the subjective assessment of intermediate audio quality. This method reflects many aspects of Recommendation ITU-R BS.1116 and incorporates the same grading scale used for picture quality evaluation (i.e. Recommendation ITU-R BT.500)."
While BS.1116 features a hidden reference, it lacks a hidden anchor. To assess intermediate audio quality, a new method was developed (more details here: https://secure.aes.org/forum/pubs/conferences/?elib=8056).
Crucially, analyzing how the panel utilizes the scale requires both the Reference and the Anchor for meaningful difference evaluations. If there's no reference, it's simply not MUSHRA but a different type of assessment. In MUSHRA, participants perform multi-comparisons and place their ratings between the reference and anchor. Without a reference, they need to establish one first. This increases the risk of inconsistency across repetitions, potentially leading to noisy data.
Would you be willing to share some more details about your experiment? I've dealt with similar questions in the past and may be able to offer assistance or point you towards someone more experienced, like Force Technology, for further guidance.
Best wishes, --- Raul Sanchez-Lopez Hearing scientist | Audio Engineer | Technical Audiologist Institute of Globally Distributed Open Research and Education On 2024-08-20 10:52, Raul Sanchez-Lopez wrote:
---------- Forwarded message --------- From: #ARIJIT BISWAS# <000003292f44871c-dmarc-request@xxxxxxxxxxxxxxx> Date: Tue, 20 Aug 2024 at 09:14 Subject: [AUDITORY] MUSHRA test with open reference; and then without open reference To: <AUDITORY@xxxxxxxxxxxxxxx> Dear all: Is there any research on how subjective ratings in a MUSHRA test might be affected if the same systems (i.e., hidden reference, anchors, codecs under test) are re-evaluated without the ability to compare them against an open reference? If no such studies/papers exist, can we make any educated guesses about the potential outcomes? I imagine that, in the absence of a reference, the task for the subjects would become more difficult. Any other guesses? Thank you. Best regards, Arijit **Disclaimer** The sender of this email does not represent Nanyang Technological University and this email does not express the views or opinions of the University.