Subject: Ultrasonic Hearing in Music Recording & Reproduction From: kent walker <kent.walker(at)mail.mcgill.ca> Date: Fri, 25 Nov 2005 01:22:32 -0500Quoting AUDITORY automatic digest system <LISTSERV(at)LISTS.MCGILL.CA>: > > Date: Thu, 24 Nov 2005 07:50:56 +0100 > From: =?iso-8859-1?Q?Lars_Bramsl=F8w?= <lab(at)OTICON.DK> > Subject: Re: ultrasonic hearing via bone conduction > > Hi Rob, > > I think the audio equipment manufacturers are trying to sell us > something we don't need with 96 and 192 kHz sampling frequency. When it comes > to air-conducted sound I haven't seen a blind study where subjects could > discriminate a 20 kHz and a 40 kHz band limited signal. > Dear Lars, At the risk of repeating myself, there are possible advantages to high sample rates which have nothing to high frequency perception. One such advantage is less pass-band ripple in the range of human hearing (although it should be noted that using higher sample-rates are not the only solution to this problem). Differences in higher sample rate recordings (DSD, 192 kHz, 96 kHz) when compared to their lower resolution counter-parts can be quite striking. If you came to the studio at the University it would be realtively easy to demonstrate that these media sound very different (even if you had a hearing aid). But are such differences due to the higher sample rates themselves, filtering differences, or something else? Indeed, it is hard to construct scientific evaluations of high-resolution audio in such a way that the results have ecological validity to the real world of making records; there are too many variables to hold constant. In order for you to state that "audio equipment manufacturers are trying to sell us something we don't need", you need to be able to produce studies that show that there are no advantages to high sample-rate music recording. Can you? Studies of hearing deficiencies may not have ANY validity to sound recording whatsoever. As I said before, there is lots of BS out there, but there is also some truth. Regarding studies of high-frequency perception, one study (though not peer-reviewed) that has reported that subjects might POSSIBLY be able to perceive such frequencies is: Ando, Akio; Hamasaki, Kimio; Nisiguchi, Toshiyuki; Ono, Kazuho, "Perceptual Discrimination of Very High Frequency Components in Musical Sound Recorded with a Newly Developed Wide Frequency Range Microphone", 2004 Audio Engineering Society Conference preprint 6298. Abstract: Subjective evaluation tests on perceptual discrimination between musical sounds with and without very high frequency (above 20 kHz) components have been conducted. To make a precise evaluation, the test system is designed to exclude any influence from very high frequency components in the audible frequency range. Moreover, various sound stimuli are originally recorded by a newly developed very wide frequency range microphone, in order to contain enough components in very high frequency range. Tests showed that some subjects might be able to discriminate between musical sounds with and without very high frequency components. This paper describes these subjective evaluations, and discusses the possibility of such discrimination as well as the high resolution audio recording of music. > > Date: Thu, 24 Nov 2005 15:17:27 -0500 > From: Pawel Kusmierek <p.kusmierek(at)NENCKI.GOV.PL> > Subject: Re: Ultrasonic Hearing in Music Recording & Reproduction > Digital equipment which records at 24/96 is easily available, and some can > use 192kHz. Digital processing is usually done in a computer, which does > not care about sampling frequency used. I think that it's harder to get a > proper mic rather than equipment. > Dear Pawel, While high sample rates are becoming "ubiquitous" a very large number of professional studios are still using recording equipment with sample rates only as high as 48 kHz. There are larger format digital consoles working at 2 x FS and more, however, to use these sample rates means doubling the processing, compromising other features such as number of channels, etc. So higher sample rates are often left aside because they can be more difficult to work with. It is extremely expensive to upgrade all of this equipment and the past 10 years have not been kind to the pocket-books of most studios; they are just trying to survive. Many (most?) pop records are still recorded using lower sample rates. Where high resolution has really "caught-on" is in Classical & Acoustic music recording, and as we have both pointed out, the large majority of the mics used to record this music "do not go up there". Creating such a mic often means sacrificing other features of a microphone which sound engineers and producers have become acustomed to. > Yes, but SACD and DVD-A, which slowly gain popularity, are capable of > going beyond 20 kHz, and, as said by Rob Maher, speaker manufacturers > continue introducing products with frequency range up to 40-50 kHz. There are a number of SACD and DVD-A titles on the market which were recorded using 44.1 kHz and 48 kHz sample rates and have been "up-sampled". Many high-profile pop recordings were/are recorded, mixed, and processed using analogue gear, allowing for a "true" high-sample rate disc to enter the customers' hands. It does seem unlikely that there is much ultrasonic content on most of these discs - although I won't say for certain until I can produce some data :-) regards, -- Kent Walker Ph.D. Candidate McGill University Schulich School of Music Sound Recording Program Instructor MUSR 300D