Those with more knowledge of a piano's inner workings (Ron?) can probably speak on this, but SK's thought that the pianist might be imparting some kind of vibration to the hammer before it leaves their control makes sense to me.

@Mary-Anna said:

I've read that some think that the quality that we perceive as a more musical tone or varying "touch" is a function of how a pianist plays in a legato or staccato style.

I haven't read any of the articles posted here except the OPs. But I have always thought something similar to what Mary-Anna said. Unscientific, but the way the end of one note blends with the beginning of the next note (and with notes that are played simultaneous or have been held before) is what I would imagine is responsible for different tone qualities. There is quite a range of possibilities for tone blending when going from one note to another. That overlap of decay and newly articulated note is where I'd focus.

@Mary-Anna said:

The reason I don't get how it works is that my understanding of the physics of a piano is that the motion of the hammer is out of the pianist's control at the time it hits the string. We can control the speed with which it hits the strings

Well, given all the parts along the line of action from the finger to the string, isn't it possible that different kinds of touch (e.g., my comment above about flat fingers vs finger tips) would create different kinds of movement (vibrations??) in different parts of the action such that when the hammer connected with the string, there would be more factors at play (har) besides just velocity?

I don't have enough control to "certify" that my flat-fingered play and finger-tip were the same velocity, so maybe differences in velocity is actually what caused the sound difference.... But still, I feel like it makes sense, mechanically. You use your body differently, it causes the hammer to "be" different when it strikes the string.

I don't know. I'm out of my depth here if the focus is physics. But it's quite interesting to consider!

What are you playing these days?

The reason I don't get how it works is that my understanding of the physics of a piano is that the motion of the hammer is out of the pianist's control at the time it hits the string. We can control the speed with which it hits the strings, making the sound louder or softer--hence the name "pianoforte"--but nothing else.

I've read that some think that the quality that we perceive as a more musical tone or varying "touch" is a function of how a pianist plays in a legato or staccato style. In other words, it comes from whether there is a separation between the notes or not or whether there is some overlap between the notes in terms of time. But this is not what the experiment tested.

However, since the experimenters were interested in human perception and not physics, their work didn't address the physical means of sound production. (I haven't read the more detailed material that you and Ax posted, but the summary that I posted suggested that it wasn't addressed.)

Ok, looking at his Google Scholar page, I'm guessing that the BulletProof Musician is where I've seen his name.
https://scholar.google.com/citations?user=IphDyJcAAAAJ&hl=en&oi=sra

Such a cool research agenda, thanks for posting this @mary-anna

@Mary-Anna said:

I don't know how this could possible work, based on what I know about how a piano works.

Or maybe the way to think about is exactly the opposite? A piano works mechanically, by objects moving through space and time and connecting with other objects.

Why wouldn't the sound change if there were changes in how that movement or connection occurred?

Ok, I'll stop spamming your thread!

https://www.pnas.org/doi/pdf/10.1073/pnas.2425073122
Motor origins of timbre in piano performance

I haven't read it yet, but I'll C&P the abstract and significance summary.

Abstract: Creativity in the arts, such as painting and musical performance, hinges on the ability to produce a wide spectrogram of perceptual experiences. In music, it has long been believed that the timbre of tones can be altered by nuanced movements of performers. Previous studies have described relationships between fundamental elements of auditory perceptions (e.g., loudness, tempo) and physical movements (e.g., force, speed), but it remains unknown whether and how delicate features of perceptual experiences such as tone timbre are manipulated through dexterous motor skills. Here, we bridge this gap using a twofold experimental approach. First, our listening test revealed that the timbral qualities pianists intended to express in piano playing were perceived as intended by both pianists and musically untrained individuals, with pianists showing a greater perceptual sensitivity to different timbres. Second, through a motor behavioral experiment using a noncontact, high-resolution sensing system, we identified five specific movement features in piano touch that were intricately linked to three categories of perceived timbre; weight, clarity, and brightness. Furthermore, the direct manipulation of a specific key movement feature resulted in systematic changes in perceived timbre, providing evidence for a causal relationship. The result indicates that pianists share common motor skills to modify perceived tone timbre by manipulating specific movement features. Our findings underscore the pivotal roles of subtle physical gestures in creating the rich timbral palette of piano tones, advancing our understanding of the intersection between motor control and artistic expression.

Significance: Understanding the mechanisms by which artists create nuanced perceptual experiences, such as tone timbre in music, has remained a longstanding scientific and artistic challenge. While it has been debated whether pianists can manipulate timbre through touch over a century, empirical evidence linking dexterous motor actions to specific timbral qualities has been lacking. Furthermore, appreciation of music performance is largely influenced by visual information, questioning auditory perceptibility of nuanced tones. A listening experiment demonstrated that the timbral qualities pianists intended to express could be reliably perceived by listening tones. Motion analyses identified a set of key movement features that allow pianists to modulate tone timbre. Our findings revealed the critical role of motor dexterity in shaping artistic expression in music performance.

Fascinating!!

Last semester, while working on one of my pieces, my teacher had me play one specific melody note with either a fairly flat finger, so that the finger pad is what connects with the key, or with a more traditional hand shape (like, where a ball could fit under your hand), so that it's the finger tip that connects with the key.

We both felt making that physical change in hand shape and in which part of the finger connected to the key made a huge change in the sound.

Probably a casual listener wouldn't notice it, or if they thought one way sounded better, they wouldn't be able to say why or even pick out the note that was different. But I think those slight changes are probably what professional pianists do all the time...