A Decibel Meter as a Free Speed Meter?

[p1n9183]

Yesterday I installed a free decibel meter in my smartphone, put it on the floor and made swings with my 6 iron without a ball. 
Also set the PRGR (speed meter) to have something to compare. 

The PRGR was giving me numbers around 90 miles per hour, the decibel meter was around 30 without a swing and jumped to 85 with the woosh of the club. 
If the whoosh of the club gets louder when you swing it faster, can a decibel meter be used as a cheep way to compare speed from one swing to another, even be used for speed training?  

 

 

 

 

[iacas]

No. You would have to be so precise with the distance and angles and what exact club you swung and the location and so so so so much.

[p1n9183]

Remember that you are measuring sound, sound waves have speed that goes in all directions. The attenuation of sound at 20°C is around 3 decibels if you are 1 meter from were the sound is created. Just set a coin on the ground and swing over it towards the same direction. You are going to have just a few cm between each swing, so attenuation is not going to be a variable.

Of course you are going to have different measures if you use different clubs! the idea is to use the same club and figure out how to swinging it faster to create more whoosh to get a higher decibel mark. 
For location of course is better at nights were is calmer and you don't have noise from the outside. 

I took the time to test it a little bit and the decibels went up and down as the PRGR also went up and down with the different swing speed I tested. 

What other things you think can mess with the readings?  
 

 

[GolfLug]

You don't need to build an algorithm if you can build a table with PRGR and decibel readings. I proper statistician can provide better guidance but Im guessing you need hundreds of readings for each club to establish a d decibel to speed curve.

[boogielicious]

A much better use of the free Decibel Meter is to see how loud your amps are when you crank them and rock out!!! I try to keep it below 90dB (emphasis on ‘try’ 😉).

I think there are too many other variables to consider using sound. You would have to set up a designed experiment with randomized runs and block variables to really see if it’s worth the effect. I can see the following variables in addition to the normal swing speed variables:

Temperature, Humidity, wind speed, time (as in how long the experiment has been running), repetitions, angle and elevation of the meter, elevation of the ball and club above the ground, ground surface roughness and reflectivity, distance to surrounding objects like walls and ceilings. This does not include the variable in sound of different club head materials and designs.

[p1n9183]

I get that if I do a couple swing today at my home course, and later in the week at my house the decibel readings could be totally different. The surrounding environment of both are totally different so the reading are likely to be different.
But for one session only, the current one with the same environment from start to finish, if my normal swing produces 90 decibels as a base line, I should be able to test other swings in order to find one that produces more decibels and expect it to be faster than the base line.

I look at this the same way as I work with my PRGR. With 7 iron at home, my average ball speed is 115 but at my home course ball speed is around 120 (same ball, same intent. I guess this is because at my home I don't hit that hard down on the ball to prevent injuries).
So.. when the other day I tested a new swing and averaged 122 at home I knew that at the course it should be around 127 and It was almost there at 125.  
My question is.. if the environment is the same from swing A to swing B, could I compare their speeds by comparing their decibels? Not the exact speeds but witch one is faster? 

 

[iacas]

1 hour ago, p1n9183 said:

I get that if I do a couple swing today at my home course, and later in the week at my house the decibel readings could be totally different. The surrounding environment of both are totally different so the reading are likely to be different.
But for one session only, the current one with the same environment from start to finish, if my normal swing produces 90 decibels as a base line, I should be able to test other swings in order to find one that produces more decibels and expect it to be faster than the base line.

I really don't think it's going to be anywhere near as accurate as you think it will be. It'd require you to have the same speed at the same distance and angle to the mic every time. Otherwise, if you swung faster, but the maximum speed was another 6" past the microphone and another 2" away from it, it could read as significantly quieter.

I think you're ignoring some really basic physics here, my man. And the fact that microphones in phones are highly directional, too. It's not like an open-air mic in a quiet room.

I think this idea lacks almost all merit.

[p1n9183]

18 hours ago, iacas said:

if you swung faster, but the maximum speed was another 6" past the microphone and another 2" away from it, it could read as significantly quieter.

As I told you before, the sound attenuation is 3 db at 1 meter (38"). 
At 7" (your example) is a wooping 1 db less, for an 80db 7 iron is under 1% error. I know for sure that my PRGR is not that accurate, even my skytrak isn't that accurate. For a FREE unit seams to be promising if you can't afford a speed meter.

 

18 hours ago, iacas said:

I think you're ignoring some really basic physics here, my man. And the fact that microphones in phones are highly directional, too. It's not like an open-air mic in a quiet room.

Again, you are swinging in the same spot, over and over again in the same session. Phone position is the same , background sound is the same, environment is the same. The only difference is the peak sound you produce when you whoosh the club.  

 

18 hours ago, iacas said:

I think this idea lacks almost all merit.

You need to do a lot better to discharge an idea. 
 

 

[p1n9183]

Digging deeper... you can use the frequency of the woosh also. 

It is possible to measure the speed of an object using the noise it generates when passing through a decibel reader, 
but with some limitations and considerations.

The method relies on the relationship between the frequency of the sound emitted by the moving object and its speed. 
When an object moves at a constant speed, it generates sound with a characteristic frequency, known as the "Doppler frequency."

The frequency of the sound emitted by the object can be related to its speed using the formula:
f = (v / c) * f0
where:

- f: frequency of the emitted sound
- v: object speed
- 😄 speed of sound (approximately 343 m/s in air at standard temperature and pressure)
- f0: frequency of the sound emitted when the object is at rest

Having "C" been constant, and "f0" been unknown but equal for both swings you only need to compare the frequency of 
each swing to know how much faster or slower is a swing over the other.

 

[iacas]

3 hours ago, p1n9183 said:

As I told you before, the sound attenuation is 3 db at 1 meter (38"). 

It might be at some distances, but none are realistic. For example, if I put a microphone 2.5m away from a sound source and another 3.5m away, the fall-off there is only about 3 (2.98 I think), but your sound would have to be incredibly loud.

A microphone that picks up an 80 dB sound at 1 millimeter will only pick up about 12 dB at 2.5 meters (and it's still only 20 dB at 1m from an 80 dB sound source).

I also don't think swinging a club generates a very loud sound, and sounds that can injure your hearing require 85 dB or so.

In other words… You need to generate (at the source) an ear-injuring level of sound with your club, and if the microphone is as little as one foot away, that 85 dB is already down to ~43.5 dB. It's almost half of what it was. Swing 14" away with the same 85 dB swing instead of 12" and the same swing will read 42 dB.

Sound attenuation is subject to similar laws like light fall-off because it radiates, so it diminishes in the inverse square:

Quote

In acoustics, Stokes's law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's viscosity. It states that the amplitude of a plane wave decreases exponentially with distance traveled, at a rate α given by

I have also talked to some sound engineers, and they've laughed and said that unless you were controlling EVERY aspect of this, including:

• temperature
• distance of max clubhead speed from the microphone
• angle (both axes) to the microphone
• clubface orientation (a face open or closed will change the frequency)
• location of the max clubhead speed (reaching peak speed at the same exact place)
• everything in the vicinity, including the shoes and clothes you're wearing, the surface you're on, etc. ideally with all of them producing virtually no noise even when moving.

You'd have to control all of those to within very small margins. Even just the doppler effect is going to dramatically change your input.

4 hours ago, p1n9183 said:

Again, you are swinging in the same spot, over and over again in the same session.

No.

4 hours ago, p1n9183 said:

You need to do a lot better to discharge an idea.

No, you need to realize how wrong you've gotten all of this.

55 minutes ago, p1n9183 said:

Digging deeper... you can use the frequency of the woosh also.

See above about the doppler effect. Unless you're a swing robot, you're not going to generate the max speed at the same exact location every time.

---

Tell me, @p1n9183, why do you think recording artists (singers) put their mouths so damn close to the microphone?

On 9/23/2024 at 7:59 AM, iacas said:

No. You would have to be so precise with the distance and angles and what exact club you swung and the location and so so so so much.

[billchao]

I know there are a lot of people on the site with science and engineering backgrounds here so @p1n9183 is getting a lot of questions about how this theory would even work, but I’m going to ask the obvious one here… why?

Like what is the purpose if you already have a speed radar, even if such a thing as you proposed was feasible?

[boogielicious]

29 minutes ago, iacas said:

Tell me, @p1n9183, why do you think recording artists (singers) put their mouths so damn close to the microphone?

And pull their mouth away when they hit stronger notes. Mics can only take so much sound pressure. Every mic is different too.

As I stated above, there are many variables to account for to even remotely have a chance to use sound to measure velocity. It would have to be in an extremely controlled environment with calibrated sound and metering devices. In addition, the swing must be absolutely repeatable as would the contact. 

There is no possible way to use the dB meter on my iPhone to accomplish this. It’s not rational to think you could. It’s not even that good at measuring the sound level of my amps accurately. Even reorienting it by 45 degrees changes the level.

[GolfLug]

16 minutes ago, billchao said:

I know there are a lot of people on the site with science and engineering backgrounds here so @p1n9183 is getting a lot of questions about how this theory would even work, but I’m going to ask the obvious one here… why?

Like what is the purpose if you already have a speed radar, even if such a thing as you proposed was feasible?

He said he installed a free decibel app on his phone. He himself has a PRGR apparently but if the idea had merit, others could benefit. It's a noble thought but there are obvious reasons why the info could be misleading from a speed measurement perspective.  

I still think a very elementary was to see if there is merit is simply swing the club at different know speeds (verified by a PRGR) and see what decibels he gets. I suspect that even with all things robotically even, a club travelling at 80 MPH doesn't register decibels sufficiently different values, if at all, than one travelling at 85 MPH,  90 MPH, etc. 

Edited September 25 by GolfLug

[iacas]

I mean, this would be the easiest thing in the world to test… but I already know the results.

• Put my GCQuad down in speed measuring mode.
• Make some swings and note the speed it says versus what a decibel meter reads on my phone.

The results would be laughably bad.

So bad, I'm not going to spend the ten minutes it would take to do such a thing, because I know what the results would be.

[GolfLug]

5 minutes ago, iacas said:

I mean, this would be the easiest thing in the world to test… but I already know the results.

• Put my GCQuad down in speed measuring mode.
• Make some swings and note the speed it says versus what a decibel meter reads on my phone.

The results would be laughably bad.

So bad, I'm not going to spend the ten minutes it would take to do such a thing, because I know what the results would be.

I would have thought that would be the first thing to do if to see if this had merit. Maybe he has.. @p1n9183?

[billchao]

1 hour ago, GolfLug said:

He said he installed a free decibel app on his phone. He himself has a PRGR apparently but if the idea had merit, others could benefit. It's a noble thought but there are obvious reasons why the info could be misleading from a speed measurement perspective.  

That just brings me to my original thought that I didn’t post: just test it. If he’s so confident in his proposal that he’s dismissing all the criticisms being posted, then why even ask for feedback?

I guess I just don’t understand the point of the topic.

[iacas]

1 hour ago, GolfLug said:

I would have thought that would be the first thing to do if to see if this had merit. Maybe he has.. @p1n9183?

You don't need to test this to know it doesn't have merit, you just have to understand some simple physical realities.

[GolfLug]

6 minutes ago, iacas said:

You don't need to test this to know it doesn't have merit, you just have to understand some simple physical realities.

Fair enough.