Hello from Oberlin, OH-Acoustics Forum-Acoustic Fields Forum

Hi everyone! I guess I qualify as a music lover – classical music in my case – being a former cellist, arts organization manager and now consultant. The reason I’ve turned to this forum is to get some help figuring out whether particular acoustic phenomena occur in a large(er) space when instrument families (e.g., voices, string instruments in the violin family, brass instruments) are used chorally in smaller and larger groups.

Specifically, what I’d like to get some input about is:

1. Do instrument families have relatively similar frequencies? I.e., if you take a vocal choir of Soprano, Alto, Tenor and Bass, a string quintet of 2 violins, viola, cello and double bass, or a brass quintet consisting of, say, 2 trumpets, horn and trombone and bass trombone, will the oscillation patterns within each instrument “family” be relatively similar?

2. Is there a higher level of oscillation pattern similarity in one or the three above mentioned instrument “families” than there is in the others (or can they be ranked)?

3. To the extent that there is oscillation pattern similarity within a given “family” of instruments, does any such oscillation similarity result in a volume or sound projection boost in an acoustic space relative to instrument groupings that mix instrument “families” (i.e., is there a measurable sound effect from using, say, a Soprano, Alto, Tenor, and Bass vocal quartet relative to using a violin, clarinet, horn and bass trombone) if exactly the same music is played at a relatively similar sound volume (dynamic)?

4. To the extent that there is (?) a measurable sound effect, is it boosted by, say, doubling or quadrupling each instrument within a “family” (so, e.g., using 2 or 4 soprano, 2 or 4 tenor, 2 or 4 altos and 2 or 4 bass voices or using 2 or 4 violins, 2 or 4 violas, 2 or 4 cellos and 2 or 4 double basses) that goes beyond the expected boost in volume resulting from adding more sources of sound?

The basis of my questions is whether similar oscillation patterns can build up on themselves to create something akin to “rogue waves” (for a definition, see https://en.wikipedia.org/wiki/…..ve_Theorem) or a build-up of “waves upon waves” that approximate something like a tsunami situation where incoming waves move more rapidly than their outflow, thus creating ever higher levels of water until the incoming oscillations subside.

There has been some research done on this acoustical topic that I’ve been able to find, but it is rather basic in that it deals with sound as it is perceived by listeners (a larger volume of deeper tones produce “extensivity” in a listener’s ear, i.e., they seem “broader in extent” rather than louder (everything being equal) relative to higher tones. The French composer Charles Koechlin proposed this effect – without providing a specific, measurable acoustic rationale – in his 1956 book on orchestration. Koechlin’s proposals were made with a mass of sound produced by masses of partially unrelated instrument families (such as you’d find in a symphony orchestra) in mind, whereas recent acoustical experiments looking at a measurable effect of his proposals all deal with the effects of single note interval sequences (one note after another) to at most two note intervals sequences (two notes sounded simultaneously vs. two notes sounded after another).

I hope the questions I have posed aren’t too incomprehensible. I’m not an acoustician and am mainly familiar with tone production first hand. I can provide you with links to the research papers that I mention above if this subject interests you.

Thanks in advance for any replies/suggestions!

TomV