Zimtohrli: A New Psychoacoustic Perceptual Metric for Audio Compression

I'm guessing the name is meant to allude to cinnamon pig ears (https://en.wikipedia.org/wiki/Palmier).

Öhrli actually. It maddens me to no end that they pick words which contain umlauts and then leave them out.

This says it works on just-noticeable-differences. Would this work well if the quality of the compressed audio is very poor? Could one for example compare two speech codecs at 8Khz, 4bit against the original source to find out which one sounds better?

Or should one just... I dunno, calculate the mean squared error in some sort of continuous frequency domain, perhaps weighted by some hearing curve.

I looked through the deeper explanation and found this interesting:

“Performing a simple experiment where we have 5 separate components

1000 Hz sine probe 57 dB SPL 750 Hz sine masker A at 71dB SPL 800 Hz sine masker B at 71 dB SPL 850 Hz sine masker C at 67 dB SPL 900 Hz sine masker D at 65 dB SPL I record the following data

When playing probe + masker A through D individually I experience the probe approximately as intensely as a 1000Hz tone at 53dB SPL. When playing probe + all maskers I experience the probe approximately as intensely as a 1000Hz tone at 48dB SPL.”

I would be very interested in understanding more about their testing methodology and hardware setup especially.

Is the perceiver a trained listener? Are they using headphones or speakers or some other transducer method?

It's awfully difficult to say that there is equivalent perceived SPL for different frequency domains, even as a trained listener. Especially given the different frequency response for different listening setups.

The average user has no chance; hence my curiosity of their specific credentials considering they’re building an entirely new perceptual model based on that.