Hi, That jitter value, was that one period jitter? Or was it jitter over a large number of periods, thus close by the carrier?
Henk > MailLists wrote: >> Ashihara's tests were with music/voice, taking into account >> psychoacoustics, for an average group of music savvy listeners, and >> even music professionals. >> As uncorrelated jitter is practically raising the noise floor, most of >> it was masked by the signal, making it more difficult to detect. >> Benjamin and Gannon used sinusoidal jitter, which isn't appearing >> normally in signal chains (badly designed ones excepted). >> In a real case, with higher probability (added) jitter would be >> correlated with the digital content transmitted over a path - S/PDIF, >> and AES/EBU are prone to jitter induced by the signal path >> characteristics, ISI - PSUs, and even external noise sources. >> A more realistic simulation would take those into account. >> OTOH there where tests on pure sine tones, with sine jitter, detectable >> by trained ears at even lower levels of jitter, which might indicate >> the lowest threshold of hearing, but using artificial conditions. >> Who would listen to pure sine tones? > > Ashihara et.al. wanted to find out what level of jitter was likely to be > audible under real-world conditions. Those conditions would likely include > music as the main signal, and random jitter. > > Benjamin/Gannon wanted to find out what levels of jitter could be detected > if the conditions were as favorable as possible for detecting jitter. That > is not the real-world situation, of course, but it can establish a > baseline where you may legitimately say that if you stay below this line > with jitter of whatever type, the effects are very unlikely to be audible. > And, to add a comment towards Attila, one of the results by > Benjamin/Gannon was that training matters a lot, and the best sensitivity > was by trained listeners. Your comment is therefore warranted, but already > accounted for. > > Hence, even though their results appear to be very different, they are > both valid, because it depends on the exact question asked. I would dare > to say, that no matter how you set up your "realistic" simulation, the > results are likely to be somewhere between the values by Benjamin/Gannon > and by Ashihara et.al. > > So, for the purpose of this group, I'd say the psychoacoustic stuff would > lead too far, but it might be helpful to know at which jitter levels one > can assume to be on the safe side in an audio system, regarding audibility > of jitter effects. Judging from the mentioned studies, I concluded (for > myself at least), that this boundary is somewhere in the single figure > nanoseconds, until someone comes forth with hard evidence that it needs to > be set lower. > > Cheers > Stefan > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.