146th ASA Meeting, Austin, TX

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Chilling Trumpets: Does It Have An Acoustic Effect?

Jesse N. Jones IV-
Chris B. Rogers
Tufts University

Popular version of paper 2pMUa6
Presented Tuesday afternoon, November 11, 2003
146th ASA Meeting, Austin, TX

Practically no trumpet player, or musician, for that matter, is 100% satisfied with the tone, playability, or consistency of his or her instrument. In an attempt to move their instruments towards perfection, some players have experimented with cryogenically treating their trumpets. The process of cryogenically treating a trumpet involves cooling it down to -300° F over the course of 8 hours, holding this temperature for 10 hours, then warming the trumpet back to room temperature over a 20-25 hour period. The process is dry, in that the trumpet is placed in a chamber cooled by liquid nitrogen, but the nitrogen never comes in contact with the trumpet.

A faction has developed within the trumpet players' culture that believes a cryogenically treated trumpet has a better tone (often referred to as timbre by musicians) and a more distinct presence. Treated trumpets play in tune more easily, as their notes are "more centered." Furthermore, proponents of the process claim that treated trumpets are more responsive and less fatiguing to play. Firms that offer cryogenic processing say that the treatment results in a trumpet that is artificially aged, the internal stresses due to manufacturing are relieved, and the crystalline structure of the brass is altered

Since 1998, Tufts University has had an active Musical Instrument Engineering (MIE) program. An unprecedented partnership of the Music, Mechanical Engineering, and Electrical Engineering departments, the program encompasses curriculum development, undergraduate courses, and research projects. These research projects are conducted either by undergraduates solely or by collaborating graduate and undergraduate students. One of the most significant examples of these collaborations is the cryogenic trumpet project.

In 1998, Selmer Musical Instruments, manufacturer of many orchestra wind instruments including the widely renowned Vincent Bach Stradivarius trumpet, became interested in offering the treatment as a factory option. Before moving forward, they first asked Tufts to independently verify the beliefs mentioned above.

In order to verify that the treatment has a definitive effect on the trumpets, we approached our research from three distinct perspectives: materials science, quantitative acoustic measurements, and qualitative player responses. Our sample set was comprised of 10 Bach Stradivarius trumpets randomly picked from the Selmer production line, half of which were cryogenically treated. We then enlisted six players of proficiency ranging from beginner to professional, with each participating in between two and four data collection sessions.

The materials science phase of this research found no changes in the crystalline structure of the brass on the microscopic level. Identifying, verifying and quantifying changes in the material is ultimately irrelevant if the trumpet sounds and plays the same after it has been treated. Thus we began looking for differences in acoustic properties between the two sets of trumpets. As scientists, it is not up to us to decide what sounds "good," "warm," or "tubby," (much less to correlate this vernacular with quantitative data). We can identify differences in timbre by measuring frequency content of a sound and graphically displaying what frequencies are present. From this, we get a quantitative description of the sound. We can also compare these graphs of the average frequency amplitudes of the two sets of data and easily calculate the difference in sound. These graphs are especially powerful, because they can tell us the amplitudes of the harmonics (e.g. overtones or partials). Further, we can calculate the frequency content of the steady tone in the middle of the note or look at how the frequency content develops in the beginning, or attack, of a note.

When we compared the average frequency content of the treated trumpets to the untreated set for each player, no conclusions could be drawn regarding the influence of the cryogenic treatment. The amplitudes of the frequencies were scattered greatly, and the related uncertainty in the data was far greater than any differences seen between the two sets of trumpets in all but one isolated case (a particular player playing a particular note, the E5). In this single case the treated trumpets had more power on average in the higher harmonics, indicating a "brighter" or more trebly sound (often cited as a trait of cryogenically treated trumpets).

We repeated the anomalous data set some months later and the difference was not seen again. Interestingly, this player, a student at the New England Conservatory, came in for his first recording session at the end of a summer that was comprised of more sailing than trumpet playing. His second set of data was collected near the end of his senior year, during which he had been practicing many hours a day and performing in public weekly. The overall difference in timbre between the two sets of data was much greater than the difference we had originally seen between the treated and untreated trumpets. Apparently, simply practicing your trumpet does more to change one's tone than does freezing it, even for advanced players. Finally when comparing data from different players, the difference in timbre between some players is even more pronounced.

The most interesting, if not entertaining, data comes from the qualitative results. The trumpets were played and examined in a random, double blind fashion, such that neither the player nor the researchers were aware if the trumpet under examination had been treated. Players were asked to rate each trumpet on a scale of 1-10 for the categories of tone and playability. They were also asked to record general impressions of each instrument, then guess if the trumpet had been treated based on those attributes that are commonly associated with cryogenic trumpets. Players' opinions of a single trumpet often varied greatly from session to session. The most pronounced came from the professional player. In his first session he identified a particular trumpet as virtually unplayable, stating that he "couldn't imagine anyone liking this horn." In his next session, one week later, he cited this trumpet as being his 2nd favorite of the 10. When guessing which trumpets had been treated, the players as a group were correct 52.5% of the time, with individual players guessing correctly between 40% and 60% over the course of their sessions.

It could be argued that it is the opinions of the players that should carry the most weight, as they are the ones buying, playing, and perhaps making their living performing on the trumpets. Although the treated trumpets garnered slightly higher average scores with regard to tone and playability, the data was again scattered widely, and no definitive conclusions can be drawn.

Some people say that players may prefer treated trumpets because of a placebo effect leading to greater confidence and, in turn, better playing. Maybe people simply want to believe that the treatment works. No one wants to pay to have his or her trumpet frozen only to get back an unchanged instrument. Finally, it is possible that the treatment does improve the trumpets, but our methodology did not capture the difference or our data collection and analysis was not sensitive enough to detect the difference. However as far as we can tell, the difference from trumpet to trumpet, player to player, and session to session far overshadow any difference brought on by cryogenic treatment.

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