From: Simon Richards <>
Date: Tue, 20 Jan 2004 21:12:21 +0000
Subject: [TPIN] Cryogenics - The Study

I have been in touch with Chip Jones, the author of the study in question, and I have now read his Master's Thesis and a scientific article he has published on the subject. They are available at the following web address, together with a lay language article, and I urge anyone with an interest in this to read them.

In my opinion this study is scientifically sound (no pun intended) and it shows that there is no statistically significant effect of cryo treatment on the sample of trumpets studied (10 new Bach Strads). If there is any effect it is so small as to be obscured by other sources of variability (from player to player, or from day to day for a single player, for example).

[pause to let that statement sink in]

You should read the experimental details for yourselves, but briefly they randomly selected 10 new Bach Strads (Model 180, 37 bell, lacquered) from the Selmer production line, and randomly selected 5 of those to receive the cryogenic treatment. They had 6 players who each played all the trumpets in a double blind trial. They recorded each player playing the open harmonics of each horn and analysed the power spectra of each note using the fast Fourier transfom (FFT) to analyse the steady-state phase of the note and the short time Fourier transform (STFT) to analyse the attacks. They also asked each player to provide a qualitative analysis of each trumpet and, in the case of those who had previous experience of playing cryo treated horns, they asked them to guess which horns had been treated. Ultimately their results are based on the 3 most proficient players in the group.

The results show no statistically significant differences between the two groups of horns in any of these tests. There are some subtle differences in some of the results, but these were inconsistent, in some cases not repeatable, and not statistically significant.

Now, no real experiment is perfect and a key assumption in this study is that the 10 trumpets are identical, aside from the fact that half were given the cryo treatment. The authors acknowledge that this assumption is not completely valid due to the individual characteristics of hand-crafted instruments. They presume that subtle variations will be averaged over the sample size. This is fair comment as long as the sample size is large enough - so is it? Given 10 trumpets randomly organized into two groups, what is the probability of there being a systematic difference between the two groups? It's possible, but unlikely. The probability gets even smaller as you increase the sample size, but in the real world we have limited research budgets.

Personally I would have liked to have seen the testing and analysis carried out on the 10 horns before half of them were treated, as well as afterwards, but again budgetary constraints have to be taken into account. Nevertherless I believe the results to be scientifically valid.

Another limitation of the study is that it is confined to the Bach Strad. Now although there are apparently quality-control issues with some Strads they are, in general, well-made high quality professional trumpets. If there was an effect and if it was due to assembly stresses then perhaps if would be more apparent on cheaper instruments. But I guess nobody is getting a cryo done on a Lark or a Bundy?

Other proposed explanations for any perceived effect of cryo treatment are the chem clean or placebo effect. This study takes the chem clean out of the equation because it uses all new horns. I'll discuss placebo in a separate post, as this one is getting long!

Dr. Simon Richards

O.J's Trumpet Page