Musical instrument acoustics

Interesting: I went to look up exactly what a sound post does, and it’s not so much transmitting vibrations between the top and bottom plates as it is providing a fulcrum so that the bridge can transmit the sideways vibrations of the strings (constrained by the bow pressing on them) to vertical vibrations in the body. Plucked instruments like guitars don’t need that because the strings can vibrate in all directions

Music StackExchange: What’s the purpose of a sound post?

Diagram of the bridge, sound post and body of a violin, showing how the side-to-side motion at the top of the bridge (where the strings pass over it) are transmitted to vertical movements on the body of the violin via rotating around the point where the sound post and one of the bridge supports meet on opposite sides of the top plate of the violin body.    Image via the stack exchange answer linked here.

Expanded on K2R

Parenting music lesson snafu

Kid’s gotten interested in playing music & has been trying out various instruments over the last few months. (Yay for rentals!)

The latest is cello. When we got it home he noticed the bridge was off-center. He can replace a string, but we all agreed to wait until his first lesson & let the teacher adjust it.

He had his first lesson yesterday, with the same teacher he took violin from a few months ago. First order of business was to adjust the bridge…

So the teacher started carefully loosening the strings while holding the bridge (which is held in place entirely by the tension of the strings) until she could shift it into place. And as soon as it moved, we all heard a loud *THUNK* from *inside* the cello.

The sound post, which both provides structural support and transfers vibrations between the front and back of the instrument, had fallen out.

And was rattling around inside the cello.

(He wants me to point out that when it happened, he reacted immediately saying “Oh no! SOUND POST!”)

So she immediately had to retool the lesson since he couldn’t, you know, play an instrument that was his size (he’s tall for his age, but it’s all in his legs) and just kind of introduce him to bass clef and the basics of how violin and cello differ.

Amazingly, we were able to make it to the music shop before closing (10 minutes to spare!) and swap it for another one.

So in theory, he can actually practice before the next lesson.

Thread start on
Expanded on K2R

Some butterflies spotted the other day while hiking.

Some #butterflies spotted the other day while hiking. A gulf fritillary (orange), some kind of blue, possibly a marine blue (tiny with brown wings and a blue body), and possibly a cloudless sulphur (yellow).

The blues are always hard to spot because they’re so small, and the sulphurs just don’t want to pause most of the time. But the fritillaries are more willing to stop, and there were SO MANY of them at the gardens on Monday.

#nature #photo #butterfly

A yellow butterfly with a few dark spots perched on a small red flower with its wings closed.

A bright orange butterfly with narrow black stripes and a few white spots outlined in black, perched on wide green leaves with its wings open.

A very small butterfly with brown wings and blue body perched on a plant with crinkly green leaves.

On Photog.Social

Maybe a cloudless sulphur? Whatever it is, these yellow ones hardly ever pause long enough for me to take a picture.

Sulphur? on iNaturalist

There were so. many. fritillaries.

Fritillary on iNaturalist (tighter crop)

Blue on iNaturalist (tighter crop)