# Which and how different factors affect the sound made by the collision of tiny solid particles?

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In daily life, the sound of mixing flour is almost undetectable; the sound of hitting the sandbag is dull;
The maracas used as a musical instrument has a bright and loud sound; the sound is clear and melodious.
The sound produced by the earth's particles under the disturbance of external forces is affected by many factors and produces different sound characteristics.

So I wander which and how different factors actually affect the sound made by the collision of tiny solid particles such as sand. And I'm eager to learn the mathematical expressions between the sound and different physical factors.

P.S. The sound here is not restricted to a single factor; and the physical factors here should only be related to the particle itself, the container or the outer force that causes the collision.

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Size, shape, speed, impact point.  In practice, probability distributions are used.

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15 hours ago, erpxry2001 said:

In daily life, the sound of mixing flour is almost undetectable; the sound of hitting the sandbag is dull;
The maracas used as a musical instrument has a bright and loud sound; the sound is clear and melodious.
The sound produced by the earth's particles under the disturbance of external forces is affected by many factors and produces different sound characteristics.

So I wander which and how different factors actually affect the sound made by the collision of tiny solid particles such as sand. And I'm eager to learn the mathematical expressions between the sound and different physical factors.

P.S. The sound here is not restricted to a single factor; and the physical factors here should only be related to the particle itself, the container or the outer force that causes the collision.

Is this a schoold project ?

Very nice if so.

1 hour ago, mathematic said:

Size, shape, speed, impact point.  In practice, probability distributions are used.

I'd love to see how probability distributions are used to distinguish between a snadbag and a maracas ?

OK if we are talking about sounds that can be made using granular materials, I would start but observing the difference between sounds generated by 'soft' materials such as flour, soft breadcrumbs, foam rubber chunks etc

and

'Hard' materials such as macaroni, dry sand gains, hard plastic beads, steel shot, etc.

A simple sound test can be made by pouring a stream of these onto

a) a hard surface such as a formica table top, a sheet of steel, glass or marble etc.

b) a soft surface such as a rubber sheet, a cloth over the hard surfaces,  etc.

For each test you may be able to distinguish two types of sound.

a) The sound of the stream of granules impacting upon the test surface.

b) The sound the stream makes as the particles bump together as you pour.

For a maracas you need (a) in both cases. The sound is made by stopping and starting the 'stream', as it bumps agains first one side then the other of the container, followed by a trailing sound of the hard particles bunmping together because the maracas is not full.

For a sandbag you need a soft cloth surface (bag) more nearly fully filled and you strike the bag, which you do not do with the maracas (which you shake).
The principle sound will be the softer sound of a few of the grains rubbing rather than bumping together as the bag and contents distort in shape. There will be no impact sounds against the soft cloth walls.

Sand grains are hard in both cases.

In the case of flour it is the flour grains themselves whicha re soft and so capable of significant distortion when bumped against each other.
It is this distortion that absorbs the energy which would be given out as sound if the grains were hard.

I wish you well with your investigation,

It is a fine project.

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On 10/7/2021 at 12:10 AM, studiot said:

In the case of flour it is the flour grains themselves whicha re soft and so capable of significant distortion when bumped against each other.
It is this distortion that absorbs the energy which would be given out as sound if the grains were hard.

To your excellent summary, I would stress the point that porous media - whatever the solid particle physical properties - make for first-class sound absorbers by their very nature. For a critical case scenario, google Hesco Bastions.

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On 10/6/2021 at 7:10 PM, studiot said:

Is this a schoold project ?

Very nice if so.

I'd love to see how probability distributions are used to distinguish between a snadbag and a maracas ?

OK if we are talking about sounds that can be made using granular materials, I would start but observing the difference between sounds generated by 'soft' materials such as flour, soft breadcrumbs, foam rubber chunks etc

and

'Hard' materials such as macaroni, dry sand gains, hard plastic beads, steel shot, etc.

A simple sound test can be made by pouring a stream of these onto

a) a hard surface such as a formica table top, a sheet of steel, glass or marble etc.

b) a soft surface such as a rubber sheet, a cloth over the hard surfaces,  etc.

For each test you may be able to distinguish two types of sound.

a) The sound of the stream of granules impacting upon the test surface.

b) The sound the stream makes as the particles bump together as you pour.

For a maracas you need (a) in both cases. The sound is made by stopping and starting the 'stream', as it bumps agains first one side then the other of the container, followed by a trailing sound of the hard particles bunmping together because the maracas is not full.

For a sandbag you need a soft cloth surface (bag) more nearly fully filled and you strike the bag, which you do not do with the maracas (which you shake).
The principle sound will be the softer sound of a few of the grains rubbing rather than bumping together as the bag and contents distort in shape. There will be no impact sounds against the soft cloth walls.

Sand grains are hard in both cases.

In the case of flour it is the flour grains themselves whicha re soft and so capable of significant distortion when bumped against each other.
It is this distortion that absorbs the energy which would be given out as sound if the grains were hard.

I wish you well with your investigation,

It is a fine project.

I was referring to an impact between a pair of specific objects.

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1 hour ago, mathematic said:

I was referring to an impact between a pair of specific objects.

But the OP was specifically referring to lots of specific objects ?

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